DE3210749A1 - LIGHT-EMITTING SEMICONDUCTOR COMPONENT WITH CURRENT LIMITATION AND METHOD FOR THE PRODUCTION THEREOF - Google Patents

Description

Wen tern Kloctric Co. Inc. Dixon, R '. Yi \ * M -2 * - 8 ° _: H /}) ·; '] * ·' [■? /: ■ '' ■ ·

Light-emitting semiconductor component with current limitation and method for its manufacture

The invention relates to light-emitting semiconductor components, for example lasers and light-emitting diodes (LEDs) the preamble of claim 1 and a method for producing such components.

Almost 20 years ago, light-emitting semiconductor components, in particular components with a flat pn junction in a monocrystalline semiconductor body, large area electrical contacts on opposite major surfaces of the body for supply a voltage in the forward direction and an excitation current have been used for the pn junction. In a light emitting diode (LED from Light Emitting Diode) generates the resulting radiation recombination of holes and electrons spontaneous radiation in the active pore near the pn junction. A fundamental change primarily causes a light-emitting diode to become a laser, namely the formation of a cavity resonator on the semiconductor body through a pair of parallel crystal cleavage surfaces at right angles to the pn junction. When the excitation current If the threshold value for a laser radiation exceeds, the spontaneous radiation, which in the Light-emitting diode emanates isotropically from the active area, converted into stimulated radiation that is emitted in the laser as a polished beam parallel to the pn junction and along the resonator axis. Naturally other design considerations play a role in the progress from light emitting diodes to lasers, however these things are not explained here, since on this fit el Ie Iod Iq 1 ich ei ι <. · known "relationship: '. wi; u: lu'ii I „ι ho r η with pn - Übcrcjancj and I. Leuchtdiodc-Hi nngogobon become target.

The wide-area contacts (with a width of, for example 100 .mu.m) on these components cause the excitation current density at the pn junction to be relatively is low, which therefore means that relatively high currents (for example a few 100 mA in lasers) were required to achieve the desired radiation output. In turn, high currents heat the semiconductor body and make a thermal coupling of the component with a suitable heat sink and / or ciiu-n Operation at cryogenic temperatures required. the The basic solution to this problem then consisted and still consists in the area of the pn junction to reduce that has to be excited, so that the required excitation current for a given current density is correspondingly lower. One implementation of this solution is to limit the excitation current to one relatively narrow channel (e.g. 12 µm in width) from a major surface of the semiconducting body through the active zone.

One of the earliest structures to contain the stream, such a channel was a contact with a stripe geometry, which was first used for semiconductor lasers by R.A. Furnanage and D.K. Wilson (U.S. Patent 3,363,195) has been. The strip geometry reduces the threshold value current for the induced laser radiation (in comparison to lasers with large-area contacts) and limits the spatial expansion of the output beam. There have been numerous laser designs since this early suggestion have been developed to realize the concept of strip geometry:

(1) the oxide stripe laser;

(2) the proton-bombarded laser;

(3) the mesa stripe laser;

(4) the laser with insulating, reverse biased pn junction;

(5 ) Ki ppen- WeI lon Lt- i Ut 1 .i; u>r;

(6) buried metal structures of various types; n ".

However, the most widely used structure over the past 11 years is the proton-bombarded GaAs-AlGaAs-DoppeJ heterostructure (DH) laser described, for example, by H.C. Casey, Jr. and M.B. Panish in "Heterostructure Lasers", Part II, pp. 207-210, Academic Press, Inc., N.Y., N.Y. (1978). Despite their different Disadvantages, lasers of this type have consistently had a predicted lifespan of more than 100,000 hours, and a number of them have exceeded a million hours (on the basis of accelerated aging tests) .. A long service life is also important for DH-LEDs using different contact geometries (for example point shapes or circular rings), but one similar proton bombardment to contain the current channel has been predicted.

Various disadvantages of proton-bombarded DH-LaiHM η has been published by R.W.Dixon et al. in "Thο Bell System Technical Journal ", Vol. 59, No. 6, pp. 975-985 (1980). The authors experimentally explored the optical non-linearity (presence of "kinks" in the light-current (L-I) characteristics) and the threshold current distribution of AlGaAs-DH ~ lasers with stripe geometry and proton bombardment containment as a function the stripe width (5, 8 and 12 µm) in cases in which the protons have penetrated or not penetrated the active zone. They showed that a flat Protonon bombardment with acceptably narrow stripes (for example 5 µm) to a usable optical table Linearity can lead ("kinking", wandering to not disturbing, high current values), without worsening the threshold value in connection with narrow stripe lasers occurred in which the protons penetrate the active zone. On the other hand, with lasers such narrow stripes a statistically significant, but not shown as a fundamentally significant reduction in service life. In addition, the fact increases that the protons do not penetrate the active zone,

the capacitance of the component, which reduces the response speed and, moreover, the lateral current propagation and accordingly the spontaneous emission can be increased. In digital systems, the latter means A higher modulation current to achieve a given extinction ratio or a lower extinction ratio for a given modulation current.

The invention has a high optical linearity, low capacitance and low spontaneous emission in GaAs-AlGaAs-DH lasers with stripe geometry and proton bombardment confinement achieved by means of a current restriction in which the current channel on the top is close is close to the p-side contact and wide at the bottom near the active zone. This structure can be applied to systems with other materials, namely light emitting diodes as well as lasers, and a number of structures besides the DH structure use.

According to an embodiment for a light emitting Semiconductor component according to the invention, a semiconductor body has an active zone within the Body and means of containment through which a stream flows from a surface of the body to the active zone and thereby creates a radiating recombination of holes and causes electrons in the active zone. The containment means are located within the semiconductor body. '; and form a flow channel that is narrow at its top close to the surface and close to the active at the bottom Zone is far. In a specific embodiment, the delimitation means form a trapezoidal cross-section Channel . In another embodiment the limiting means form a coupled pair of axial Kn η ei 1 e η unt π srli i <> d 1 i cht r Write, where Ίΐιτ γτκ; μ ' Channel near the surface? and the other channel n.'ihe

.5T) dor nktivon for lying.

-ΙΟ-

In a further embodiment of the invention the current limiting means comprise first means with an elongated groove (e.g. a V-groove) in the main surface, the relatively narrow canal which leads into the body to a depth just before the active zone, as well as second means (for example Proton-bombarded zones), which form a relatively wide, second channel, that of at least this Depth into or through the active zone. In an alternative embodiment, the first include Means zones of relatively high resistivity near the main surface, at least part of it the inclined sides of the V-groove, i.e. the V-groove penetrates these zones. In an additional embodiment the V-groove is filled up again with semiconductor material.

Another aspect of the invention relates to a particle board cement process for the production of such a component with a trapezoidal channel. The procedure looks first propose epitaxial growth of a removable semiconductor layer on the major surface of the body and then the layer is exposed to an etchant with preferential properties, the inverted trapezoidal shape Stripes exposed in the layer. The remaining parts of the

25th layers form a trapezoidal (in cross-section) attenuation mask. If the masked surface is bombarded by particles (e.g. protons, oxygen) exposed, there are high resistivity zones in the parts of the body between the Masks and created under the very flat sides of the trapezoids. These zones delimit the flow channel and give it the desired trapezoidal shape: at the top near the surface narrow and down near the active zone. Before the metallization of the body to form electrical contacts the mask is removed. For this purpose, the mask is preferably made of a material that has different

that of the part of the body near the surface, so that an etch stop method is used in the removal can be.

The invention is described below with reference to the drawings. In the interests of greater clarity, those are Figures are not drawn to scale. Common elements in the different figures have, as far as appropriate, identical reference numerals are given. In the figures show:

Fig. 1 is a perspective view of a

borrowed-emitting semiconductor component with a trapezoidal flow channel according to an embodiment of FIG Invention;

Fig. 2 is a view of a light emitting

• Semiconductor component with trapezoidal Current channel according to a further embodiment of the invention; Fig. 3 is a view of a light emitting Hi-Lo semiconductor component with two disconnected

set channels according to a further embodiment of the invention; 4 shows a view of a mask structure for producing a light emitting Component with trapezoidal flow channel

according to a feature of the invention; 5 and 6 alternative masks for the production of components according to the invention by means of a proton bombardment; Fig. 7 is a perspective view of a

Semiconductor laser or a light emitting diode ¹ according to an embodiment of the invention;
8 shows a cross-circuit view of a laser or a light-emitting diode accordingly

another embodiment of the Invention in which a V-groove in a zone of high resistivity penetrates;

Figure 9 is a cross-sectional view of a laser

or a light-emitting diode in accordance with a further exemplary embodiment of FIG Invention in which the V-groove is again filled with semiconductor material.

1 shows a light-emitting semiconductor component (laser or light-emitting diode) with a semiconductor body which includes a central zone 14. Zone 14, which may have one or more layers, contains an active zone which emits radiation 22 when supplied with an excitation current. To feed the Excitation current are electrodes, for example contacts 16 and .18 on the body 11, together with a voltage source 20. Also includes the body 11 containment means 32 which cause the excitation current flows in a relatively narrow channel 36 from the upper contact 16 through the active zone. After that you can the current to the ground contact 18 fan out.

Before the invention is explained in detail, it should be useful to the general properties of a to describe preferred structure of a light-emitting semiconductor component as a double heterostructure (DH) is known. According to Fig. 1, 2 and 3 has a double heterostructure a first: and a second capping semiconductor layer. 10 or 12 made of a material with

M) moderately large gaps and opposing force. L - capability, as well as a substantially lattice-matched middle layer 14 between and near the cover layers. The middle layer 14 contains an active layer with a smaller band gap, which is shown here as extending in the same way as the layer 14 and

Can emit radiation if the covering layers have been prestressed in the through-direction. From the standpoint of quantum efficiency, it is known that the active layer is preferably a direct band gap semiconductor. Layers 10, 12 and 14 can be made from materials selected from a number of systems, such as GaAs-AlGaAs or GaAsSb-AlGaAs for operation at short wavelengths, in the range of about 0.7-0.9 µm as well InP-AlGaAsP or InP-AlGaInAs for operation at wavelengths greater than about 1 μm , for example 1.1 to 1.6 μm. ■

The voltage source 20 biases the cover layers in the forward direction and thereby injects charge carriers into the active layer. These carriers recombine and generate spontaneous radiation in the case of a light-emitting diode and predominantly stimulated radiation in the case of a laser. In both cases, however, the radiation has a wavelength which corresponds to the band gap of the material as the active layer. In addition, in the case of a laser or a light-emitting diode emitting at the edge, as shown in FIG. 1, the radiation 22 is emitted in the form of a beam along the axis 23. In the laser, the beam is focused, and the axis 23 extends at right angles to a pair of resonator mirrors 24 and 26, which are formed, for example, by crystal cleavage surfaces or etched surfaces. These mirrors represent an optical feedback device for the stimulated radiation. In other applications, for example with integrated optical circuits, diffraction gratings can be used as a replacement for one or both mirrors .

The one with the laser or the edge-emitting light-emitting diode Although electrodes shown in FIG. 1 contain large-area contacts 16 and 18, it is known that these contacts can have different geometric shapes. In the case of a transversely emitting

Light-emitting diode where the output light is at right angles to exits the layers, the contact 16 is typically a large-area contact, but the contact 18 may be an annulus (not shown) having an etched opening (not shown) in one side of the body 11 records. If the bottom part (for example the substrate) of the body 11 is absorbent, it will be etched Opening used to couple radiation to an optical paser (not shown) introduced into the opening, is.

The conductivity type of the active layer is not critical. It can be an n-, p-conducting, intrinsic or compensated material, as in the typical operating modes with a forward bias the number of injected carriers the doping level of the active layer. In addition, the intermediate zone 14 may contain a plurality of layers which represent an active zone, for example closely spaced p- and η-conductive layers of a material same eland gap, which form a pn-homojunction, or oi nc · .s material; -; with. uri t or the cute band .lückon, which form a pn heterojunction. In addition, the heterostructure can have other configurations than the simple Double heterostructures including, for example and not limited to, separate containment heterostructures . which are described in US Pat. No. 3,691,476, of heterostructures with buried Strips of the type described in U.S. Patent 4,190,813 and isotype heterostructures of US Pat in U.S. Patent Application 050,637. '

For continuous (CW) laser operation at room temperature, the thickness of the active layer is preferably between about λ / 2 and 1.0 μm, where ^{λ is} the · WoI 1 en Liinq- · di.M. "Sti tih.1 urifj measured in Semiconductor is. Püx "a tie--

When driven at low thresholds, the thickness is typically between 0.12 and 0.20 µm. For LED operation however, a thicker active layer, typically 2 to 3 µm, is suitable. In both cases it is for one operation at room temperature the laser or the light-emitting diode typically on a suitable heat sink? (not shown) attached.

In practice, the layers of a double heterostructure are typically made using an epitaxial process grown, for example a liquid phase epitaxy (LPE), a molecular beam epitaxy (MBE) or by chemical metal-organic vapor deposition (MO-CVD). The epitaxial growth takes place on a single crystal substrate 28 which has a buffer layer (not shown) between the substrate 28 and the first cover layer 1Ö. It is also appropriate 1 and 3, as an optional option, a layer 30 facilitating contact between the second cover layer 12 and the upper contact 16 are present. The opposite contact 18 is on the bottom of the substrate 28 is made.

As mentioned above, are - around the generated by the source 20- ■ th excitation current to flow on a relatively narrow channel 36 through the active zone - containment means 32 in the body 11, i.e. there are zones 32 of high resistivity by known means formed in the semiconductor layers, for example in layers 10, 12, 14 and 30. Regarding the method for Formation of the zones 32 include, for example, proton bombardment, oxygen bombardment, or a suitable one Etching and re-waxing of material with high specificity Resistance. For illustration, the zones 32 have a specific resistance in the order of magnitude 10 to 10 Ω "cm, while the channel 36 has a specific Has resistance of only 0.1 Ω "cm, so that typical proportions for the speci f j i_; ehc «n resistances in the range of

-16-lÜ ⁶ : Ibis ΙΟ ⁷ : 1 lying.

Trapezoidal channel structures

According to the embodiment of the invention according to 1, the current limiting means 32 form a stream

■ ^Γ) f.Lußkannl 3b relatively high conductivity., Which is narrower at its top near the main surface 44 (width S 1) and at its bottom near the active zone (ie the layer 14) is wider (width S 1). The delimitation means 32 comprise laterally separated zones 32.1 and 32.2 with a high specific resistance, which delimit the channel 36 along its inclined sides 36.1. Although these sides are shown as straight lines, a linear relationship is not required in practice, nor is it actually found in practical machining methods.

It has been found that the above-described form of the Current channel has important influences on the quality of the component. The narrower channel at the top increases the current density and accordingly the power at which kinks occur. The depth of the zones of high resistivity, which preferably extend through the active zone 14, affects the capacitance of the component and the height of the spontaneous emission generated in lasers. These relationships will be explained in more detail later.

Alternatively, as shown in FIG. 2, the channel 36 formed by the zones 32.1 and 32.2 with a high specific resistance does not need to reach the main surface ΛΑ. However, so that the resistance of the component does not become too high, a dopant can be diffused into the surface 44 or introduced in some other way in order to generate a highly conductive diffusion front 45 which penetrates into the channel 36. In this case, the width S. at the top of the channel 35 is determined by the line of intersection of the front 45 with the inclined sides 36.1.

The implementation of the containment means 32 according to the invention is not limited to configurations in which the channel is trapezoidal in shape. In the next Section, the Hi-Lo structures explained form the means of containment 32 a coupled pair of consecutive channels.

Although, in addition, the trapezoidal channel 36 after Fig. 1 essentially forms a parallelepiped / which is parallel to the. Axis 23 extends can in the case a cross-emitting light-emitting diode, the channel 36 have the shape of a truncated cone, the axis of which is perpendicular stands on the layers.

Hi-Lo structures

According to this embodiment of the invention shown in FIG. 3, the flow restricting means 32 have a two-stage or offset configuration in which two channels 36a and 36b coupled to one another are formed. Specifically, the means 32 include first means 32.1a-32.2a defining a relatively narrow upper channel 36a and second means 32.1b -32.2b defining a relatively wide lower channel 36b dof ini oron, as an example include the limit means 32 zones 32.1-32.2 with high specific resistance, which delimit relatively highly conductive channels 36a and 36b. The zones 32 include upper zones 32.1a, 32.2a and lower zones 32.1b, 32.2b. The upper zones are separated by a relatively small distance S i and extend from the upper major surface 44 of the body 11 to a depth d, just before the active zone, and thereby define the narrow upper channel 36a '. In contrast to this, the lower zones are separated from one another by a relatively large distance S 1> S 1 and extend from the depth d into or through the active zone and thereby define the wider lower channel 36 b.

As before, the channels 36a and 36b can be touched Form cine «have parallelepipeds that are perpendicular extends to the plane of the paper, like a laser or an edge-emitting light-emitting diode. In a cross-emitting light-emitting diode, they can form cylinders that extend across the layers.

When the high resistivity zones 32 are created by proton bombardment in GaAs-AlGaAs lasers this hi-lo structure has several advantages. First, the narrow upper channel 36a increases the current density in the active zone and thereby causes kinking to sufficiently high stroin values outside the range of a typical Laser operation can be shifted compared to DH lasers with wide (e.g. 12 µm) stripe geometry. Second, this feature also leads to lasers with more evenly distributed and lower ones Threshold values for the laser radiation, whereby higher yields are achieved. The third is because the broad one lower channel 36b has reduced lateral current diffusion and propagation, less spontaneous radiation emitted outside the laser resonator, resulting in smaller minimal modulation currents for given extinction ratios are possible in digital applications. Fourth, the latter feature leads to a reduced one Capacity for both laser and light emitting diodes, which enables a higher working speed (i.e. higher pulse repetition rates in digital applications).

To reduce the component capacity, the proton bombardment penetrate the p-n junction, which is located at one of the Boundaries between the active zone 14 and the cover layers 10 and 12 is located. To reduce the spontaneous emission, however, the protons should preferably pass through the active zone in which the

Recombination occurs.

Production of tra pe z-shaped channels

As shown in Fig. 4, there is one manufacturing facility of the trapezoidal channel according to Fig.l therein, epitaxially a removable semiconductor layer of the main surface 44 and using known photolithography and preferential etching processes to shape the layer to form inverted trapezoidal openings 54, which are portions of the major surface 44 expose. Between the openings form the remaining portions 52 of the removable layer trapezoidal attenuation masks. For a semiconductor layer made of a III-V compound material, the inclined side walls 56 correspond to the remaining sections (111A) crystallographic planes forming an angle of approximately 45 ° with a (100) oriented face 44.

Alternatively, the openings can be in the removable layer are etched in the form of inverted trapezoids, such that. the remaining sections 52 are trapezoids. In both Cases accordingly, the trapezoids and inverted trapezoids are complementary.

Bombarding the masked area 44 with particles 50 (for example protons, oxygen) leads to a deepest proton penetration between the sections, no penetration under the central (thickest) parts of the sections and a gradually decreasing penetration under the sloping sides of the sections. Of course it would a thinner mask section allow some proton penetration under the central parts. This method would be useful when realizing the channel configuration according to FIG. 2.

After the end of the bombardment and before the metallization to form electrical contacts are the

Removed debuffs. For this purpose, it is expedient if the material of the mask 52 is different from the part of the body 11 near the surface 44, so that etch stop processes can be used with advantage. For example, surface 44 is preferably made of GaAs, in which case the mask 42 could be made of AlGaAs. Then a known HF etchant or an iodine etchant (for example 113 g KI, 65 g I ₂ , 100 ml [I ₂ O) can be used as a stop etchant to remove the mask 52. An E'lasma stop paw can also be used as a substitute for wet chemical processes. Finally, it should be noted that a buffered peroxide solution is also a preferred etchant and can be used to etch the openings that form the mask portions 52.

The creation of the removable layer also leads to a flushing benefit in terms of the cleanliness of the epitaxial Growing. If an epitaxy from the liquid phase to produce the semiconductor layers of this Components is used, the last layer grown is typically from different sources poisoned, especially by globules of molten metal (e.g. Ga) used as a source solution. Accordingly, this last layer, which is usually the cap layer or contact facilitation layer 30, must be used (Fig. 1-3) 1st to be cleaned by etching. This process step requires careful control, since the layer 30 is typically very thin (for example 0.5 μm). With the procedure described here however, the last layer grown is the attenuation mask, which can be significantly thicker (e.g. 3.0 µm) and easily removed by stop etching processes leaves, as stated above.

Manufacture iJ_u_ncj_ of Hi-Lo structures

, _r Listen to the Hi-Lo-Sl. A number of manufacturing methods can be used in the ruk door of the invention

will. As mentioned above, the zones 32 with high resistivity can be exposed to proton bombardment, Oxygen bombardment or etching and regrowth of high resistivity material can be formed. To the For the explanation, however, it is assumed that these zones are formed by proton bombardment.

One easy to miss procedure uses two proton bombardment steps and two masks. In the first step, a proton attenuation mask having a width S 1 and protons of energy E 1 (for example 150 kev) are used to contain the narrow upper channel 36a. In the second step, a proton attenuation mask with a width S "and protons of energy E"> E ₁ (for example E "= 300 kev) are used to delimit the wide upper channel 36b.

A delimitation of the channels 36a and 36b by a single proton bombardment step is also possible. A composite attenuation mask with higher proton attenuation in the center and lower attenuation on the sides can be used for this purpose. Two variants of this type of mask are shown in FIGS. In both cases, a thick metal strip 40 of width .S _{1 is formed} on top of a plateau 42, which in turn is arranged on the main surface 44 which is located closest to the active zone 14. The strip 40 essentially completely attenuates the protons 50, so that no proton destruction takes place in the narrow channel 36a, and the plateau 42 only partially weakens the protons 50, so that damaged zones 32.1a and 32.2a can be removed to a depth d .. just before the active zone. Outside the plateau 42 the mask produces practically no attenuation, namely not in FIG. 5 because the mask does not extend that far, and not in FIG. 6 because the mask is very thin there. Accordingly, outside of the Pl. Monui; 42 the damaging lon zones J ?. .Ib and 3 2. 2b up to one

a depth d "and penetrate into the active zone 14. The damaged zones j? .Lb and 32.2b preferably lead - as shown - through the active zone 14 In nciui cn. As an example, strip 40 in Figures 5 and 6 includes gold plated. The plateau 42 comprises in Fig. 5 layers of Au (42.1), Pd or Pt (42.2) and Ti (42.3) and in Fig. 6 a mesa of SiO ₂ (42.4) on which Ti-Pt layers (42.5) rest.

The following examples describe in more detail how masks of this type are used in the manufacture of light-emitting

Components have been used. Unless otherwise stated, numerical parameters and various materials are given for illustration only and are not intended to limit the scope of the invention. In each of the two 1Γ) examples, the semicircular body 11 comprises an n-GaAs substrate 28 with a (100) orientation on which the following epitaxial layers are grown by standard LPE: an n-GaAs buffer layer (not shown), a η-Al ^ ,, Ga, -. As covering layer 10 with a thickness of about 1.5 µm, a p-Al ₀ o ^Ga g ₂ ^As ~ ^{Al <;t;}'- ^vsc ' ^i: '- ^{ch1 :;} - ^ with a thickness of about 0.15 µm, a p-Al ^ / - Ga _ß . As cap layer 12 about 1.5 µm thick and a highly doped p-GaAs cap layer 30 about 0.5 µm thick. The complete plate O body II ^s with epitaxial layers) was processed in accordance with the description below for the production of light-emitting components, in particular lasers.

Example I.
To fabricate lasers using the composite attenuation mask 40-42 of Figure 5, a lift-off photoresist mask was applied to surface 44 and standard photolithography techniques were used to create an elongated, stripe-shaped window having a width of 12 µm or 18 µm opening perpendicular to the {110} cleavage planes. After another

were then Ti, Pd and Au layers 42.3, 42.2 and 42.1 deposited using a vacuum electron gun system. The deposition rate was determined by a commercially available Monitoring system controlled in such a way that the Ti, Pd and Au layers had thicknesses of 1000 and 1500 and 5000 Angstroms, respectively. The total thickness of 0.75 µm for the Plateau 42 was chosen to have a 50% reduction the penetration depth of protons 50 with 300 keV. The strip-shaped plateau 42 was then known by Etching process formed to lift off the photoresist mask.

Thereafter, the strip 40 was also in the form of a 5 µm wide strip by electroplating of gold to a thickness of about 1 to 2 µm using standard photolithography techniques. The gold strip 40 forms a practically perfect barrier for the protons of high energy (300 keV; dosage

15-2
tion 3 χ 10 cm), whereby a narrow upper channel 36a of width S '= 5 µm and a wider lower channel 36b of width S = 12 µm or 18 µm are produced.

Between the values S, and S _? the plateau 42 causes only a partial attenuation, so that protons penetrate to a depth d 1 = 1.5 μm. Outside of S_ there was no attenuation mask and the protons penetrate to a depth d "= 2.8 µm and consequently penetrate the active layer 14.

Example II

To simplify the production process according to the example I became the Ti-Pd-Au plateau 42 as shown in FIG. 6 by a dielectric strip 42.4 (for example SiO "or Si .. N.) replaced on the a Ti-Pt layer 42.5 rests on it. This composite mask was made by depositing SiO 2 to a thickness deposited from about 1.0 to 1.2 µm on surface 44 using standard vapor phase processes.

This gap! was again chosen so that a

50% attenuation of the protons 50 with 300 keV results. The SiO2 layer was then delimited photolithographically and in a cjepuff locate standard HE 'etchant Etched perpendicular to the {110} cleavage planes to form slraps 12 µm or 18 µm wide. To Removing the photolithography mask, the SiO_- Strip 42.4 and area 44 by standard vapor deposition techniques covered with Ti at 1000 Angstroms and then Pt at 1500 Angstroms.

Finally, the strip 40 having a width of 5 µm and a thickness of 1-2 µm was made using conventional Photolithography and electroplating processes generated.

As before, the masked platelets were using protons

15-2300 keV and exposed to a dosage of 3 χ 10 cm, around the narrow upper canal 36a and the brcvil on at the same time create lower channel 36b. In this case, the layer 42.5 reduces the proton energy so that d "to about 2.3 µm decreases.

In both Examples I and II, the assembled masks 40-42 were made after completion of the proton bombardment removed from surface 44 using an HF etchant. This process step also prepares the area 44 for a subsequent metallization to form the usual p-metal contacts.

Experimental Results - Hi-Lo Structures To provide a comparison standard, half of each semiconductor plate in Examples I and II was processed into control lasers with 5 µm wide strips by a flat proton bombardment (150 keV). Each remaining half wafer was processed into Hi-Lo lasers using three types of composite masks 40-42 as explained above: Type (1) - a 5 µm wide Au strip 40 on an 18 µm wide SiO ,, / TiPt plateau 42 (Example II); Type (2) - 5 µm wide Au strip 40 by 12 µm wide

SiO ₂ / Ti-Pt plateau 42 (Example II); Type (3) - 5 µm wide Au strip 40 on 18 µm wide Ti-Pd-Au plateau 40 (Example I).

The comparison values given in the table below are based on a number of parameters:

Spontaneous emission performance S ₁ . at 50 mA driver current;

Li

Slope Δ S of the spontaneous emission section of the

Ij

LI curve; Capacitance C measured at 1 MHz (mean capacitance is given below); the minimum modulation current MMI, which is the current difference between the upper and lower light power level P _? or P _{1 is} defined, which leads to a light intensity extinction ratio E _R between the switched-on and switched-off state when the laser is operated in the form of a pulse. (The mean value MMI is given below for E _D = 15: 1, P "= 2.5 mW and P ₁ = 0.16-7 mW.)

Laser type ^S L
(mW) ^AS L
(mW) ■ MMI
(mA) C.
(pf) Control type 0.200 0.29 59 83 Type (1) 0.151 0.28 45 21 Control type 0.142 0.20 76.5 115 Type (2) 0.042 0.07 24 35 Control type. 0.071 0.12 70.5 .54 Type (3) ■ 0.041 0.06 26th 12th

In addition to the data shown in the table, it was found that 90 % of the lasers of type (2) had MMI values within a specified MMI current of 30 mA with a statistical fluctuation of 2σ-3ηιΛ. Similarly, 75 % of Type (3) lasers had MMI values within 30 mA, while none of the corresponding control lasers had such values. This result-

-26-se mean an improved yield of rough parts.

Note that the lasers of type (2) with strips of width S "= 12 by the greatest decrease from S.. And the highest

ί Lj

have the highest yield for MMI _ <30 mA, but these advantages alone do not necessarily determine the use of such a strip width. Attention must also be paid to the output light power level P i at which kinks occur. In general, it was found that kink formation occurs at higher P, values in the control lasers than in the Hi-Lo lasers, but that the latter are still within the specified values (i.e. P, _> 3 mW) . The type (1) lasers showed a small change in the value of P i. The lasers of type (2), in which the narrowest attenuation masks (S = 12 µm) were used, showed a remarkable reduction of about 50 % of the value P compared to the control lasers. In contrast, the lasers of type (3) with a value S n = 18 had a smaller reduction of about 35 % of the value P 1. These data suggest that it is appropriate to choose values for the width S_ between 12 µm and 18 µm.

The first means defining the narrow upper channel 36a can be realized by means of a groove which is etched into the top major surface 44. Accordingly, it is to be expected that one groove in combination with a wider one lower channel 36b has features and advantages comparable to the designs given above. the Details of such a structure are given in connection with FIGS. 7 to 9 described.

FIG. 7 shows a light-emitting semiconductor component (laser or light-emitting diode) analogous to those according to FIG. 1-6. It has a semiconductor body 111 with a central zone (114). This zone 114 can be one or have multiple layers and has an active zone which, in the case of a laser, was predominantly stimulated

.32Λ O7Λ9-

Radiation 122 or, in the case of a light-emitting diode, spontaneous Emits radiation when an excitation current is supplied. An electrode device such as contacts 116 and 118 on the body 111 is provided together with a voltage source 120 in order to supply the excitation current deliver. In addition, the body 111 has containment means 132-134, which cause the excitation current in a relatively narrow channel 136-138 from the upper Contact 116 flows through the active zone. The current can then spread in the direction of the ground contact 118.

In accordance with the embodiment of the invention shown in FIG. 7, the flow restriction means 132-134 include first means 134 defining a relatively narrow upper channel 136 and second means 132 defining a relatively wide lower channel 138. For explanation, the containment means include first means 134 in the form of a V-groove, which extends from the upper main surface 144 to a depth dr shortly before. the active zone and thus defines a relatively narrow upper channel 136. Furthermore, laterally separated zones 132 with high resistivity are provided which delimit a wide lower channel 138 which _{leads to the active zone from at least approximately the depth c} (ie in or through the active zone). As shown, the separated zones 132 preferably extend from the major surface 144 through the active zone. The V-groove 134 lies in the space between the zones 132. It is not essential, however, that the zones 132 of high resistivity actually extend all the way to the main surface 144. In practice, for reasons of contact, it may be advantageous to have a layer of high conductivity between the zones 132 and the contact 116, as described in US Pat. No. 4,124.

In the double heterostructure (DH) according to FIG. 7, the V-groove 134 has a width S_ on the main surface 144 and a depth D ₅ with which it penetrates into the second covering layer 112 and thus defines the upper channel 136, which in the has essentially the same width. In contrast, the zones 132 with high resistivity are separated by a greater distance S.> S ₃ and extend from the main surface 144 to a depth dg> d, - in and preferably through the active zone and thus define the broader lower one Channel 138 with the width S ..

Alternatively, according to FIG. 8, the upper channel 136 can be further delimited by additional zones 132.1 with high specific resistance, which delimit part of the inclined sides 134.1 of the V-groove 134 and thus the width S ^{1 of} the upper channel according to FIG. 8 Define smaller than the width S_ according to FIG. 7. In practice, the zones 132 and 132.1 can be produced (for example by proton bombardment) to a depth d _c or d ₇ (d _fi > d ₇ ). The V-groove 134 can then be etched to a depth dj- so that it penetrates into the zones 132.1 (d_, <d, - <dg).

These V-groove embodiments show several advantages. First, the narrow upper channel 136 increases the current density in the active zone and therefore shifts the kinking Laser, to higher current values out of the typical operating range out. Second, this characteristic should also lead to a more even distribution of the threshold values for laser operation and lead to lower threshold values for this operation, so that a higher building oil yield results. Thirdly, there is the wider lower channel 138 for the lateral diffusion and propagation of current reduced, less spontaneous radiation is emitted outside the laser resonator, so that a smaller Modulation current for a given cancellation ratio

ratio is possible with digital applications. To the fourth, the latter feature leads to reduced component capacity, both in lasers and with light-emitting diodes, which enables a higher operating speed, i.e. higher pulse repetition rate cn in digital applications).

Further arrangements can be developed by a person skilled in the art on the basis of these basic ideas, without departing from the scope of protection of the Invention deviate. In particular, the V-groove 34 in FIG. 7 or 8 can again be made with a semiconductor material can be filled up, thus obtaining components (especially lasers) that have several useful properties as described below. Furthermore Although the groove has been described as a V-groove, its exact geometric shape is not critical. One V-groove results when III-V semiconductors are determined Etchants are exposed that etch preferably crystallographic planes, but V-grooves or rectangular Grooves can also result from other etchants or other processes (for example ion beam milling) or plasma etching).

According to FIG. 9, the V-groove is filled with a semiconductor material 134 '. Depending on the method used layers can be used to achieve replenishment 134.2 are formed, which are close to the V-groove and / or the main surface 144. In addition, it can be dependent on the material of the cover layer 112 and the type of process used, the material 134 'is epitaxial material (i.e. monocrystalline) or not.

There are several exemplary embodiments depending on the relative size of the band gaps E of the DH layers with respect to that of the material 134 'of the V-groove. Case I: E (134 ')> E (114); i.e. the material 134 'of the V-groove has a larger band gap than the material that is active Layer 114. As Krgubni «shows a laser radiation that

penetrates into the material 134 'of the V-groove, a reduced absorption compared to FIG. FaJl II: E (134 ')> E (112)> E (114); in addition, the covering layers 130, 112 and the active layer 114 all have the same conductivity type and the material 134 'of the V-groove and the covering layer 112 have opposite conductivity types. This structure is a form of an isotype laser in which the pn junction is located along inclined surfaces 134.1. In this case, the material 134 'of the V-groove is preferably monocrystalline material. Case III: E (112)> E (134 ¹ )> E (114); ie

g g g

the material 134 'of the V-groove has a smaller band gap than the material of the covering layer 112, but a larger band gap than the material of the active layer 114. As a result, the refractive indices η have the relationship η (114)> n (134') > η (112) so that the laser radiation is guided along the V-groove due to the refractive index.

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Claims (21)

BLUMBACH · WESER. BERGEN Vt (RAM ¹ ER '''". ZWiRNER - HOFFMANN PATENT LAWYERS IN MUNICH AND WIESBADEN Patentconsutl Radeüceslraße 43 8000 Munich 60 Tulelon (08?) R8 '.605 / 883604 Telex Ob-112313 relogrommu Fnlnnlronsuli Patentconsiill Sonnenbergpr Str ^ Po 43 6200 Wiesbaden Telephone (06121) ΜΛΜ3 / 5Ϊ1998 Iclox 04-186 2J7 TelrciuMiim Piilenlrorrnll Dixon, R.W. 14-2-i3-8 / 9-9-34 / 35 Western Electric Company Incorporated 222 Broadway, New York, N.Y. 10038, United States of America - Claims Light-emitting semiconductor component with a semiconductor body which has an active zone in which when a current flows, optical radiation is generated, and means in the semiconductor body for limiting of the stream in such a way that it flows from a major surface of the Body flows in a channel through the active zone, characterized in that the channel is narrow near the main face .and near the active one Zone further. 2. Semiconductor component according to claim 1, characterized in that the containment means first Have means that cause the stream to flow in a relatively narrow upper channel, the of the Main surface to a depth just before the active zone leads, and second means that cause the flow flows in a relatively wide lower channel, which leads from this depth to the active zone. 3. Semiconductor component according to claim 2, characterized in that the second means are a pair include second zones with high resistivity, which limit the lower channel. Munich: R. Kramsr Dipl.-Ing. · VV. Weser Dipl.-Phy; ·. Dr. r.ur. nat. · E. Hoffmann Dipl.-Ing. Wiesbaden: PG Blumbach Dipl.-Ing. · P. Bergen Prof. Dr. jur. Dipl. Ing., Pai.-Ass., Pat.-Anw. until 1973 G. Zw'rnoi Dipl.-Ing. DU> i- ^J 'V.-lng. O L IU / MO 4. HalblGitorbaute.il according to claim 3, characterized in that the second zones lead through the active zone. 5. Semiconductor component according to one of claims 2 to 4, characterized in that the first means comprise a pair of first high resistivity zones, which limit the upper canal. ' 6. Semiconductor component according to one of claims 3 to 5, characterized in that the high resistivity zones are proton bombarded zones. 7. Semiconductor component according to one of the claims 2 to 6, with a first cover layer, a second cover layer closer to the main surface than the first Layer, and an active zone comprising an active layer between the cover layers, characterized in that the upper channel extends from the major surface to a depth which is located in the second cover layer, and that the lower channel extends from this depth the active layer extends. 8. Semiconductor component according to one of claims 2 to 7, characterized in that the upper channel is about 5 µm wide and the lower channel between about 12 and 18 µm are wide. 9. Semiconductor component according to one of the preceding. Claims mi !: a laser resonator axis along which jLij.ch radiation spreads, characterized in that the means of containment the channels as elongated parallel epipede defined that are essentially parallel extend to the axis. 10. Semiconductor component according to one of claims 1 to 8 for use as light emitting diodes, characterized in that the containment means define the channels as cylinders, which extend across the zone. 11. Semiconductor component according to one of claims 1 to 7, characterized in that the containment means have a location similar? Groove include that causes, i.e. the current in the relatively narrow upper canal that flows extends from the main surface to a depth just short of the active zone, and a second device which causes the current to flow in the relatively wide lower channel extending from at least this depth extends to the active zone. 12. A semiconductor component according to claim 11, characterized in that the first groove is a part the main surface in which a V-groove is formed, and two laterally separated first zones with high specificity Resistance, the at least part of the inclined »ropes cloi V-groove ljr-cjrvn / .cn, doi.wt, d.ili dii · V-NuI dir penetrates first zones. 13. Semiconductor component according to claim 11 in conjunction with claim 7, characterized in that the groove leads from the main surface to a depth in the second covering layer and that the lower channel extends through the active layer from at least this depth. 14. Semiconductor component according to claim 11 or 12, characterized in that the first device is a ^ n Part L of the surface in which the groove is formed and semiconductor material filling the groove. 15. Semiconductor component according to claim 14, characterized in that the semiconductor material has a larger band gap than the material of the adjacent parts of the body owns. 16. Semiconductor component according to claim 14, ' characterized in that the semiconductor material has the same conductivity type as the adjacent parts of the body has. 17. Semiconductor component according to claim 14, characterized in that the semiconductor material is opposite Has conductivity type like the neighboring parts, creating pn junctions on the sides of the Grooves are formed that inject charge carriers into the active zone. 18. Semiconductor component according to claim 14, characterized in that the semiconductor material has a smaller band gap than the adjacent parts of the body and has a larger band gap than the active zone. 19. A method for producing a component according to claim 1 with a trapezoidal flow channel in one Semiconductor body with the process step: a) epitaxial growth of a semiconductor layer on a main surface of the body, characterized by the process steps: b) Pattern production on the layer below Rilduna of trapezoidal openings in the layer, the remaining sections of the layer have complementary trapezoidal masks with sloping side walls in cross-section bi! den, c) irradiating the body with ninom diving- bombardment - to create zones of high resistivity between the masks and under the slopes Sidewalls, d) removing the masks from the main surface. 20. The method according to claim 19, characterized in that the layer and the part of the body near the main surface consist of different semiconductor materials and that in the process step d) the masks are removed by a stop etching process. 21. The method according to claim 19 or 20, characterized in that the layer and the body Group III-V compounds include that the major surface has a (100) crystal orientation and that at Process step b) the openings are produced by exposing the layer to an etchant which preferably along the (111A) crystallographic Etches planes so that the side walls form the planes.