JPH06244506A - Semiconductor display and its manufacture - Google Patents

Abstract

PURPOSE:To obtain a stable and highly reliable semiconductor display capable of lattice matching by the use of a low-cost substrate of GaAs, etc., and excellent in crystallizability and productivity by integration-forming three red, green and blue primary-color light-emitting parts composed of II-IV compound semiconductors on the same substrate through one crystal growth. CONSTITUTION:On the same substrate 1, three primary-color light-emitting parts composed of II-IV compound semiconductors are integration-formed through one crystal growth. Zn (SSe) is used as blue light-emitting part 4b; (ZnCd) (SeTe), as green light-emitting part 4g; and Cd (SeTe), as red light- emitting part 4r. These light-emitting parts are held between first and second conductive clad layers 2 and 6 so that three primary-color light-emitting parts are formed. Also, GaAs is used for the substrate 1, respective light-emitting parts 4b, 4g and 4r are formed into LEDs or LDs, and the light-emitting parts are arranged in a predetermined direction in the order of blue, green, red, green and blue through one crystal growth.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor display device, and more particularly to a semiconductor display device capable of performing color display by self-emitting light of three primary colors of red R, green G and blue B.

[0002]

2. Description of the Related Art A red light emitting device is manufactured by epitaxially growing a group III-V element on a GaAs substrate. Further, it has been proposed to fabricate a matrix of red light emitting devices by producing a plurality of these on the same substrate.

Further, it is desired to form a blue light emitting element and a green light emitting element to obtain a three-primary-color light emitting element. However, light emission at room temperature is red even if AlGaInP capable of emitting light of the shortest wavelength is used. Not available, and blue light emission is possible with BN-based compound semiconductors, etc., but GaAs and Ga, which have excellent crystallinity and productivity and are easily available and inexpensive
Since the lattice constants of the P substrate do not match, the three primary colors I
It was difficult to form II-V group elements on the same substrate with good productivity.

[0004]

On the other hand, GaAs
II-VI group elements, such as (Cd _0.2 Zn _0.8 ), on the substrate
By epitaxially growing Se sandwiched by ZnSe, green-emitting LEDs (light-emitting diodes) and LDs
(Laser diode) can be manufactured.

Furthermore, the applicant of the present invention, in the previously filed Japanese Patent Application No. 4-32253, etc., uses ZnSe as ZnMg.
Blue light emitting L
D, proposed to construct LED.

No structure or manufacturing method has been proposed in which such light emitting elements are formed on the same substrate. For example, although there is a report of a display device in which the respective elements are arranged side by side, the size of one pixel is about 5 mm. There is a problem that it is relatively large, and the entire display area becomes 10 inches or more.

The present invention is a completely new semiconductor display device in which the composition of the compound semiconductor layer is changed and the three primary color portions of R, G and B of self-emission type are formed on the same substrate by one crystal growth. I will provide a.

[0008]

According to the present invention, as shown in FIG. 1 which is an enlarged schematic cross-sectional view of an example thereof, a three primary color light emitting portion made of a II-VI group compound semiconductor is formed on the same substrate 1. An integrated structure is formed by crystal growth.

According to the present invention, in the above structure, the blue light emitting portion 4b is Zn (SSe), the green light emitting portion 4g is (ZnCd) (SeTe), and the red light emitting portion 4r is C.
Using d (SeTe), at least Z
n (SSe) or (MgZn) (SSe) first
It is sandwiched by the conductive type clad layer 2 and the second conductive type clad layer 6 to form a three primary color light emitting part.

Furthermore, the present invention has the above-mentioned structure.
The substrate 1 is made of GaAs. Further, in the present invention, in the above structure, each of the light emitting portions 4b, 4g and 4r is an LED,
Alternatively, it is configured as an LD.

Furthermore, the present invention applies the above-mentioned configuration to a projection type display device. Further, in the present invention, in the above structure, the light emitting portions are arranged in a predetermined direction in the order of blue, green, red, green and blue by one crystal growth.

Further, according to the present invention, as shown in a manufacturing process diagram of one example thereof, as shown in FIG.
The step of growing the first-conductivity-type cladding layer 2 made of a group VI compound semiconductor and the light emitting portion 4 made of a group II-VI compound semiconductor are controlled by a mask to control the composition ratio thereof as shown in FIG. And a step of growing the second-conductivity-type cladding layer 6 made of a II-VI group compound semiconductor.

[0013]

As described above, in the present invention, the three primary color light emitting portions R made of II-VI group compound semiconductors are formed on the same substrate.
G and B are integrated and formed by crystal growth, and an active layer made of a II-VI group compound semiconductor is formed by controlling the composition ratio thereof using a mask so that one crystal growth can be performed. A self-luminous display device with high definition can be formed.

That is, ZnS, (ZnC
d) (SeTe), Cd (SeTe) blue, green and red light emitting active layers are controlled in order of blue, green, red, green and blue by controlling the composition ratio of Zn and Cd using a mask, for example. It becomes easy to form them on the same substrate by one-time crystal growth. And these active layers are ZnSe or (MgZn)
With the structure sandwiched by (SSe), red, green, and blue light emitting elements, that is, LEDs or LDs, are formed on the same substrate.
Can be integrally formed by crystal growth.

When materials are selected in this way, these 3
Since the primary color light emitting active layer and the clad layer can be lattice-matched with a substrate such as GaAs or GaP which has excellent crystallinity and productivity, is easily available, and is inexpensive, it is extremely stable and has a practically sufficient life. be able to.

A projection-type display device can be constructed by forming these elements in a one-dimensional array and scanning and irradiating the light emission corresponding to the information signal from the element with a polyhedral mirror or the like. Further, by integrating the light emitting element on the substrate as described above, a self-luminous semiconductor display device with high definition can be realized.

[0017]

Embodiments of the present invention will now be described in detail with reference to the drawings. In this example, ZnS is used as the blue light emitting portion.
e, (ZnCd) (SeTe) is used as the green light emitting portion, Cd (SeTe) is used as the red light emitting portion, and these light emitting portions are made of ZnSe or (MgZn) (SSe).
An example of a display device in which a three-primary-color light emitting portion is made to emit light as an LED or an LD, is sandwiched between a conductive type, for example, an n-type clad layer and a second conductive type, for example, a p-type clad layer.

FIG. 4 shows MBE as an example of a crystal growth apparatus.
The schematic block diagram of the vapor deposition apparatus by the (molecular beam epitaxy) method is shown. In this case, a substrate holder 12 for holding the substrate 1 is provided in a vacuum container 20 which is set to an ultra-high vacuum (pressure of about 10 ⁻⁷ Torr or less), and the surface of the substrate 1 supported on the substrate holder 12 is provided. A plurality of molecular beam sources 11 are provided at opposite positions.
A so-called K cell and a plasma generation source 21 by RF (high frequency) or ECR (electron cyclotron resonance), for example, are provided. Reference numeral 22 is a magnet, 23 is a microwave terminal, 24 is a gas introduction pipe for introducing N ₂ gas or the like, and 25 is a shutter.

C is placed between the substrate 1 and the molecular beam source 11.
To control the composition of d and Zn, for example, two masks 1
3, the mask 13 can be opened and closed in synchronization with the shutter 25 of the plasma generation source 21.

Using such an apparatus, the crystal growth of the three primary color light emitting portions can be performed by the following steps. In this example, the case of emitting light as an LED is shown. First, high-purity Zn, Cd, S, Se, and Te as raw materials and Cl as a dopant are filled in different molecular beam sources 11, respectively. In FIG. 4, only four molecular beam sources 11 are shown. Further, the substrate 1 made of GaAs or the like whose surface is cleaned is mounted on the substrate holder 12. The inside of the vacuum vessel 10 ^-8
After exhausting to about Pa, the molecular beam source 11 is heated and adjusted so that an appropriate molecular beam intensity is obtained.

Next, the substrate is heated to about 600 ° C. to further clean the surface. Then, the substrate temperature is lowered to about 300 ° C., and the growth of the compound semiconductor layer is started. In this case n
When growing the p-type crystal, Cl is irradiated from the molecular beam source 11, and when starting the p-type crystal growth, the mask 13 and the shutter 25 are opened synchronously, and at the same time, the plasma generation source 2
Each of the growth is performed by irradiating the plasma of 1 to N.

In this embodiment, as shown in FIG.
N-type ZnS as the first conductivity type cladding layer 2 on the substrate 1
After growing e, ZnSe- (CdZn) (SeTe)
The light emitting section 4 having the multiple quantum well (MQW) structure is manufactured. The color of emitted light can be changed by modulating the composition ratio of Cd and Zn. For example, red has Cd = 1
The atomic ratio may be 00% for green, Cd = 20% for blue, and Cd = 0% for blue.

In this example, Zn (SeTe), Cd and
(SeTe) is grown alternately using the two masks 13. That is, when the Zn beam is irradiated through the mask after the Se and Te beams are applied, the Zn beam passes through the mask, for example, through a hole formed in a stripe shape and is irradiated, and a region where the Zn beam intensity becomes large has its concentration. Becomes large and becomes the blue light emitting portion 4b.

Further, after irradiating the Se and Te beams and then irradiating the Cd beam through the mask, the Cd beam also irradiates through the hole of the mask to irradiate the Cd beam.
The portion where the beam intensity is high has a high Cd concentration and becomes the red light emitting portion 4r. A region in which the Cd beam and the Zn beam are mixed becomes the green light emitting portion 4g.

In the light emitting portion thus obtained, as shown in a part of FIG. 3, Cd is gradually increased and decreased, and the distribution is such that the group II element is only Cd at the peak.
This distribution is configured as a concentration distribution which is periodically repeated on the substrate 1. A second conductivity type cladding layer 6 made of p-type ZnSe or the like is grown thereon. After that, the electrode 8A is entirely formed on the second conductivity type clad layer 6.
By sputtering or the like, so as to be divided for each color light emitting portion, that is, as a stripe pattern along the above-mentioned stripe mask, by application of photolithography, that is, application of photoresist, mask exposure, wet The groove 9 is formed by etching such as etching or RIE (reactive ion etching). Then, the electrode 8B is entirely deposited on the back surface side of the substrate 1 by sputtering or the like, whereby the semiconductor display device shown in FIG. 1 can be obtained.

In this case, the electrodes 8A and 8B are formed as thin metal electrodes or light-transmissive electrodes such as transparent electrodes such as ITO (composite oxide of In and Sn).

The cladding layers 2 and 6 may be made of ZnSSe instead of ZnS. Particularly, by selecting the composition ratio of S and Se as ZnS _0.06 Se _0.94 , perfect lattice matching with the substrate 1 can be achieved.

It is also possible to use only Se as the group VI element of each light emitting portion, and to configure the blue light emitting portion as ZnSe, the green light emitting portion as ZnCdSe, and the red light emitting portion as CdSe, respectively.

The light emitting device thus obtained is blue,
The light emitting portions 4r, 4g, and 4b of each color are formed in the order of green, red, green, blue, ... Then, by modulating, for example, the stripe width of each light emitting portion, a desired light emission intensity ratio can be obtained and white balance can be easily achieved.

Further, when the LED light emitting portion is used, for example, in the above-mentioned example, the second light emitting portion is provided on the light emitting portions 4r, 4g and 4b.
It may be configured without providing the conductive clad layer 6.

Then, by integrating such three primary color light emitting portions on a substrate in a two-dimensional matrix, for example,
For example, as shown in the schematic configuration diagram of FIG.
For example, a horizontal scanning circuit 31 and a vertical scanning circuit 32 are provided on the substrate 1 along two sides of the three-primary-color light emitting unit 30, for example, the upper side and the left side in FIG. 5, so that light emission is sequentially scanned in accordance with the information signal. For example, an image can be displayed. In this case, it is possible to obtain a self-luminous small display with high definition of about 3 inches or less.

Further, as shown in a schematic configuration diagram of another example in FIG. 6, when the three-primary-color light emitting section 40 is constructed as a one-dimensional array, by projecting this, a projection type semiconductor display device is obtained. Obtainable. 3 primary color light emitting section 40
The light emitted from is reflected by, for example, a polyhedral reflecting mirror 41, and by this rotation, scanning is performed in a direction orthogonal to the arrangement direction of the one-dimensional array and scanning irradiation is performed on the reflecting mirror 42. It is possible to configure a so-called rear projection type projection display device in which the image such as the image shown by s is projected on the surface opposite to the side on which the display is visually recognized. Reference numeral 44 denotes the apparatus main body.

Further, the present invention is not limited to such a configuration, and various modifications such as a so-called projector type display device in which the screen 1 is removed in the above-described configuration to display on a large distant screen are possible. It can be changed.

Next, another embodiment of the present invention will be described with reference to the manufacturing process diagrams of FIGS. 7A and 7B. In this case, the light emitting portion is composed of an LD, and as shown in FIG. 7A, a cladding of a first conductivity type, for example, n-type (MgZn) (SSe) is sequentially formed on a substrate 1 made of n-type GaAs or the like. Layer 2, e.g. n-type guide layer 3 made of ZnSSe or ZnSe, e.g. ZnSe- (ZnCd) (SeT.
e) laminated MQW type light emitting section 4, for example, p-type ZnSSe or ZnSe guide layer 5, (Mg
The second conductivity type, for example, p-type cladding layer 6 made of Zn) (SSe) is epitaxially grown by the apparatus shown in FIG.

Also in this case, similarly to the example described in FIG. 1 described above, the composition of the light emitting portion 4 is such that the molecular beam of Zn and Cd is partially passed through the mask 13 and the substrate 1 is irradiated with the concentration. Are modulated to grow crystals.

As shown in FIG. 7B, each color light emitting portion formed in this manner has a blue light emitting portion 4b, a green light emitting portion 4g, and
Red light emitting portion 4r, green light emitting portion 4g, blue light emitting portion 4b.
It is composed in the order of. After that, after the electrode 8A is deposited on the second conductivity type cladding layer 6, the light emitting portions 4 of the respective colors are formed.
A groove 9 for dividing b, 4g and 4r is formed by applying photolithography or the like, and an electrode 8 is formed on the back surface side of the substrate 1.
B is attached, and the light emitting end face is formed by cleavage, and the LD
It is possible to configure a three-primary-color light emitting unit according to the above.

In this case, the special feature of the above-mentioned applicant's application
As explained in the application No. 4-32253, Z
By selecting the composition ratio of nMgSSe appropriately,
Can be lattice matched to the substrate 1 made of GaAs
It FIG. 8 shows Zn_xMg_1-xS _ySe_1-yComposition in
Photo of each material with different ratios x and y
Is it a band edge emission of the luminescence (PL) spectrum?
The bandgap Eg (eV) obtained from
It is a partial addition to the plot points □ shown in Fig. 8.
The composition indicated by the straight line A is lattice-matched with the GaAs substrate.
did. Further, the curves a to i in FIG. 8 are 2.8 eV to 3.6.
The composition of the eV band gap obtained is schematically shown.
It is shown in.

As can be seen from FIG. 8, (MgZn)
By selecting the composition ratio of (SSe) to a value corresponding to the straight line A and growing the cladding layers 2 and 6 by crystal growth, lattice matching can be achieved with the substrate 1, and the characteristics such as high luminous efficiency are improved. Further, it is possible to configure a light emitting unit that enables stable operation and further continuous oscillation.

Also in this case, the guide layers 3, 5
ZnS can also be used as. However Zn
By using SSe, particularly by selecting the composition of ZnS _0.06 Se _0.94 , it is possible to achieve perfect lattice matching with the substrate.

A projection type display device can be realized by arranging the light emitting portions for emitting laser light with such a configuration side by side as a one-dimensional array and scanning the light emitting portions in one direction, for example. It is also possible to form a two-dimensional matrix type light emitting unit by directly forming the LD by, for example, forming a surface emitting type LD.

Even when the light emitting portion is formed by the LD as described above, it is possible to obtain a self-luminous display device with high definition by performing crystal growth once, and in particular, downsizing of about 3 inches or less is possible. It is also possible to obtain a projection type display device by projecting this. Further, by forming each light emitting unit by a surface emitting LD, for example, a projection type display device of about A4 size (297 × 210 mm) can be obtained.

The present invention is not limited to the above-mentioned embodiments, and various other materials can be used, and the structure thereof is, for example, between the substrate 1 and the first conductivity type cladding layer 2. Various modifications can be made such as providing a buffer layer. Further, it goes without saying that the manufacturing method is not limited to the manufacturing apparatus described above, and various crystal growth methods can be used.

[0043]

As described above, according to the present invention, II-VI
By using a group compound semiconductor, lattice matching can be performed using a substrate such as GaAs which is excellent in crystallinity and productivity and is easily available and inexpensive, and a stable and highly reliable semiconductor display device can be configured. .

Further, a projection type semiconductor display device can be obtained by producing the light emitting portions of each color in a one-dimensional array and scanning the emitted light for projection. Furthermore, by integrating the three-primary-color light-emitting portions on a substrate in a two-dimensional matrix, for example, a high-definition, self-luminous small-sized display of about 3 inches or less can be obtained.

Further, by forming each light emitting portion by a surface emitting type LD, it is possible to obtain a projection type display device of about A4 size, for example.

[Brief description of drawings]

FIG. 1 is an enlarged schematic cross-sectional view of an embodiment of the present invention.

FIG. 2 is a manufacturing process diagram of an example of the present invention.

FIG. 3 is a diagram showing a Cd concentration distribution.

FIG. 4 is a schematic configuration diagram of an example of a crystal growth apparatus.

FIG. 5 is a schematic configuration diagram of an embodiment of the present invention.

FIG. 6 is a schematic configuration diagram of another embodiment of the present invention.

FIG. 7 is a manufacturing process drawing of another embodiment of the present invention.

FIG. 8 is a diagram showing a change in band gap with respect to a change in x, y composition of Zn _x Mg _1-x S _y Se _1-y .

[Explanation of symbols]

 1 substrate 2 first conductivity type clad layer 3 guide layer 4 light emitting part 4b blue light emitting part 4g green light emitting part 4r red light emitting part 5 guide layer 6 second conductivity type clad layer 8A electrode 8B electrode 9 groove

Claims (8)

[Claims] 1. A semiconductor display device characterized in that three primary color light emitting portions made of a II-VI group compound semiconductor are integrated and formed on the same substrate by crystal growth. 2. A blue light emitting portion is ZnSe, a green light emitting portion is (ZnCd) (SeTe), and a red light emitting portion is C.
d (SeTe) is used, and these light emitting parts are made of Zn (SS
2. The semiconductor display according to claim 1, wherein the three primary color light emitting portions are formed by being sandwiched by a first conductivity type clad layer and a second conductivity type clad layer composed of e) or (MgZn) (SSe). apparatus. 3. The semiconductor display device according to claim 2, wherein the substrate is made of GaAs. 4. The semiconductor display device according to claim 1 or 2, wherein each of the light emitting units is a light emitting diode. 5. The semiconductor display device according to claim 1 or 2, wherein each of the light emitting units is a laser diode. 6. The semiconductor display device according to claim 1, which is applied to a projection type display device. 7. The light-emitting unit is configured so that blue, green, red, and
3. The semiconductor display device according to claim 1 or 2, wherein the semiconductor display device is arranged in the order of green and blue by one crystal growth. 8. A step of growing a first conductivity type cladding layer made of a II-VI group compound semiconductor on at least a semiconductor substrate, and a composition ratio of a light emitting section made of a II-VI group compound semiconductor is masked. A method of manufacturing a semiconductor display device, comprising: a step of controlled growth and a step of growing a second conductivity type cladding layer made of a II-VI group compound semiconductor.