JP5573310B2 - Optical semiconductor device and manufacturing method thereof - Google Patents

Description

  The present invention relates to an optical semiconductor device and a method for manufacturing the same.

  In optical fiber communication, from the viewpoint of reducing power consumption, there is a need for an optical semiconductor element, such as a semiconductor laser or a semiconductor optical amplifier, that does not require temperature control using a Peltier element and that can operate at a high temperature.

  In order to enable high-temperature operation of the optical semiconductor element, it is necessary to prevent leakage of carriers from the oscillation level due to thermal excitation in the energy band structure of the active layer of the optical semiconductor element. As a countermeasure, it is considered effective to apply quantum dots having discrete energy levels to the active layer.

  On the other hand, as a wavelength band of light used in long-distance optical communication, a 1.55 μm wavelength band with a small optical loss in an optical fiber is applied. As a quantum dot capable of obtaining an optical gain in this wavelength band, InAs / InP quantum dots are typical.

  Thus, as an example of forming quantum dots on the (001) plane using an InP substrate, a structure in which InAs quantum dots are formed on an InAlAs layer selected from materials having a lattice matching system is known. . The InAs quantum dots are formed in an asymmetric shape in which the length in the [−110] direction is longer than the length in the [110] direction.

  As another example, it is known to grow InAs quantum dots on an InGaAsP layer selected from materials having a lattice matching system on a (001) plane on an InP substrate. Even in this case, an asymmetrical quantum dot, that is, a quantum wire long in the [−110] direction, or a quantum dot close to a quantum dash is easily formed.

The reason why asymmetric quantum dots are formed in the above two structures is that the migration length of indium (In) atoms in the [−110] direction is longer on the (001) plane of the InP substrate than in the [110] direction. Because.
On the other hand, since migration of In atoms hardly occurs on the main surface of the InP inclined substrate inclined to the (311) B plane with a large number of atomic steps on the surface, a quantum dot having a symmetrical shape is formed on the (311) B plane. It is known that

J.Brault et al., Journal of applied physics, 92, 507 (2002) N. Sritirawisarn et al., Journal of CrystalGrowth, 305, 63 (2007) K. Akahane et al., Applied physics letters, 93, 041121 (2008)

According to the asymmetrical quantum dot, the quantum confinement effect is reduced as compared to a quantum dot having a symmetric shape. As a result, the discrete level interval formed in the quantum well is narrowed, and carrier escape to higher order levels due to thermal excitation is likely to occur. There is a concern about a decrease in light emission efficiency, and in a semiconductor optical amplifier, there is a concern about a decrease in optical gain at high temperatures.

That is, in order to improve the temperature characteristics of the optical semiconductor element, it is necessary to form quantum dots having a symmetrical shape with a large discrete level interval in the quantum well.
On the other hand, in the optical semiconductor device formed on the (311) B surface of the InP inclined substrate, the current confinement structure can be manufactured by embedding both sides of the active layer mesa shape advantageous from the viewpoint of low power consumption with the InP layer. Have difficulty.
Therefore, there is a need for a technique for producing a quantum dot having a symmetrical shape on the (001) plane of an InP substrate from which a buried current confinement structure can be easily produced from the viewpoint of low power consumption and manufacturing.

  An object of the present invention is to provide an optical semiconductor device capable of producing quantum dots having a symmetrical shape on the (001) plane and a method for producing the same.

According to one aspect, an In _x Ga _1-y As _y P _1-y layer (0 ≦ x ≦ 1, 0 ≦ y ≦ 1) is formed above the (001) plane of the InP substrate in a growth atmosphere. A step of supplying an aluminum material to the growth atmosphere, a step of stopping the supply of the aluminum material to the growth atmosphere, at least one of an arsenic material and an antimony material, and at least one of an indium material and a gallium material. Is supplied to the growth atmosphere, so that In _a Ga _1-a As _b Sb _1-b (0 ≦ a ≦ 1, 0) is formed on the In _x Ga _1-y As _y P _1-y layer. And a step of forming quantum dots of ≦ b ≦ 1).
According to another aspect, an In _x Ga _1-y As _y P _1-y layer (0 ≦ x ≦ 1, 0 ≦ y ≦ 1) formed above the (001) plane of the InP substrate, and the In _x Ga _1-y as _y and the aluminum element remaining in _{P 1-y} layer, the _{in x Ga 1-y as y} P 1-y in is formed on the layer _{a Ga 1-a as b Sb} 1- There is provided an optical semiconductor device having _b (0 ≦ a ≦ 1, 0 ≦ b ≦ 1) quantum dots.
It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not intended to limit the invention.

According to the present _{invention, In a Ga 1-a As} b Sb 1-b of the quantum dots just before forming the _{In x Ga 1-y As y} P 1-y _{layer, In x Ga 1-y As} y An aluminum raw material is temporarily supplied to the atmosphere around the P _1-y layer. Since the aluminum element suppresses migration of the group III element for forming the quantum dots in the [−110] direction, In _a Ga _1-a As _b Sb _1-b (0 ≦ a ≦ 1, 0 ≦ b ≦ The lengths of the quantum dots of 1) in the [−110] direction and the [110] direction are substantially the same. As a result, the In _a Ga _1-a As _b Sb _1-b quantum dots formed on the (001) plane have a symmetric shape, and the energy interval between the ground level and the first excited level in the energy band structure is Since it becomes larger than the conventional one, the temperature characteristic of the optical semiconductor device is improved.

1A to 1C are cross-sectional views (Nos. 1 to 3) showing a manufacturing process of the optical semiconductor device according to the embodiment. 1D and 1E are cross-sectional views (Nos. 4 and 5) showing the manufacturing process of the optical semiconductor device according to the embodiment. FIG. 1F is a cross-sectional view (part 6) illustrating the manufacturing process of the optical semiconductor device according to the embodiment. FIG. 1G is a cross-sectional view (part 7) illustrating the manufacturing process of the optical semiconductor device according to the embodiment. FIG. 1H is a cross-sectional view (No. 8) illustrating the manufacturing process of the optical semiconductor device according to the embodiment. FIG. 2 is a flowchart illustrating a process of forming an active layer including quantum dots in the optical semiconductor device according to the embodiment. FIG. 3 is a plan view showing quantum dots in the optical semiconductor device according to the embodiment. FIG. 4 is a plan view showing quantum dots according to a comparative example. FIG. 5 is a diagram showing the energy band structure of quantum dots.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In the drawings, similar components are given the same reference numerals.
A metal organic chemical vapor deposition (MOCVD) method is used as a method for forming the laminated structure of the optical semiconductor device according to the present embodiment. For example, the following raw materials are mainly used as the group III element growth raw material and the group V element growth raw material introduced into the reaction atmosphere in the reactor (not shown) of the MOCVD apparatus.

As a group III element growth raw material, triethylgallium (TEGa) which is a gallium (Ga) raw material, trimethylindium (TMIn) which is an indium (In) raw material, or the like is used. Further, as the group V element growth raw material, for example, phosphine (PH ₃ ) as a phosphorus raw material and arsine (AsH ₃ ) as an arsenic (As) raw material are used. Further, for example, silane (SiH ₄ ) is used to dope n-type impurities, and for example, diethyl zinc (DEZn) is used to dope p-type impurities.

In addition, when introducing a group III element growth raw material, a group V element growth raw material, or the like into the reactor, hydrogen (H ₂ ) is used as a carrier gas. However, in the following description, supply of the carrier gas is omitted. Sometimes. H ₂ gas alone is supplied into the reactor.
The growth pressure in the reactor is set to, for example, about 50 Torr (about 6.7 × 10 ³ Pa). Further, the growth temperature shown below is adjusted by a heater in the reactor.

Next, steps required until a layer structure shown in FIG. 1A is formed will be described.
First, the n-type InP substrate 1 whose upper surface is the (001) plane is installed in the reactor of the metal organic vapor phase growth apparatus. Subsequently, PH ₃ is introduced into the reactor to raise the growth temperature to 630 ° C.

Thereafter, PH ₃ , TMIn, and SiH ₄ are introduced into the reactor as growth source gases, so that the n-type InP buffer layer 2 has a thickness of, for example, about 100 nm to 500 nm on the (001) plane of the n-type InP substrate 1. To form. In this case, the gas flow rate is adjusted so that the doping concentration of silicon which is an n-type impurity is 5.0 × 10 ¹⁷ cm ⁻³ .
Next, the supply of TMIn and SiH _{4 into} the reactor is stopped, the inside of the reactor is switched to the PH ₃ atmosphere, and then the growth temperature is lowered to 470 ° C.

Further, AsH ₃ gas is additionally supplied into the reactor, and the inside of the reactor is set to a group V element source gas atmosphere of PH ₃ and AsH ₃ . Subsequently, TEGa and TMIn which are group III element source gases are supplied into the reactor. As a result, a non-doped In _x Ga _1-y As _y P _1-y layer having a composition wavelength of 1.1 μm is formed as a first SCH layer 3 on the n-type InP buffer layer 2 to a thickness of about 100 nm, for example. Form. In this case, x = 0.85 and y = 0.33.

Thereafter, as shown in FIGS. 1B and 1C, InAs quantum dots 4 are formed on the first SCH layer 3. Thereafter, as shown in FIG. 1D, a plurality of In _x Ga _1-y As _y P _1-y guide layers 6 and InAs quantum dots 4 are alternately formed on the InAs quantum dots 4, and the top InAs quantum dots are further formed. A second SCH layer 7 is formed on 4.
A method of forming the InAs quantum dots 4 and the In _x Ga _1-y As _y P _1-y guide layer 6 will be described with reference to the flowchart illustrated in FIG.

First, as shown in FIG. 2a, after the first SCH layer 3 is formed, the supply of TMIn, TEGa, and AsH ₃ gases into the reactor is stopped as shown in FIGS. 2b and 2c. The growth temperature is adjusted to about 450 ° C. under an atmosphere of PH ₃ .

Subsequently, after the growth temperature is stabilized at 450 ° C., as shown in d, e, and f of FIG. 2, the supply of PH ₃ is stopped, and the state in which H ₂ is introduced in the reactor is maintained for about 10 seconds. By maintaining such an H ₂ atmosphere state, PH ₃ is removed from the reactor. Since the growth temperature is as low as 450 ° C., the surface of the In _x Ga _1-y As _y P _1-y layer that is the first SCH layer 3 does not cause roughness due to phosphorus (P) loss.

Next, as shown in g of 2, by introducing triethylaluminum (TEAl) into the reactor, the first _{In x Ga 1-y As y} P 1-y SCH layer 3 of aluminum on the surface of the (Al ) The element is supplied in an amount equivalent to 1.0 ML (a monolayer).

Thereafter, as indicated by g, h, i in FIG. 2, the supply of TEAl to the reactor is stopped, and the inside of the reactor is held in an H ₂ atmosphere for 5 seconds, for example. This is to remove TEAl remaining in the reactor.
After the above processing, as shown in FIG. 1B, Al element remains on the surface of the first In _x Ga _1-y As _y P _1-y SCH layer 3.

Next, as shown by j and k in FIG. 2, AsH ₃ is supplied into the reactor for 1 second, for example, and then AsH ₃ and TMIn are supplied into the reactor.

  As a result, as shown in FIG. 1C, InAs quantum dots 4 are formed on the first SCH layer 3. In this case, the supply amount of InAs is 2.5 ML, the growth rate is 0.045 μm / hour, and the gas flow rate ratio of the group V element gas source to the group III element gas source, that is, the V / III ratio is 30. The growth conditions are set as follows. Note that an InAs wetting layer 5 thinner than the InAs quantum dots 4 is formed around the InAs quantum dots 4. Note that Al remains on the surface of the first SCH layer 3.

  The InAs quantum dots 4 formed under such conditions are symmetrical in the [110] direction and the [−110] direction, as shown in the plan view of FIG. Details thereof will be described later.

After the InAs quantum dots 4 are formed, the supply of TMIn into the reactor is stopped as indicated by l in FIG. Subsequently, as shown in FIG. 2m, AsH ₃ is supplied for 10 seconds and then stopped.
Here, when the number of upper and lower layers of the InAs quantum dots 4 has not reached the set value as indicated by n in FIG. 2, AsH ₃ and PH ₃ are placed in the reactor as indicated by o in FIG. Supply for 1 second.

Subsequently, as shown in FIG. 2p, by supplying AsH ₃ , PH ₃ , TMIn and TEGa into the reactor, as shown in FIG. 1D, non-doped In _x Ga _1-y As _y P _{1− The y} barrier layer 6 is formed to a thickness of about 40 nm, for example. In this case, x = 0.85 and y = 0.33.
Thereafter, as shown by q in FIG. 2, the supply of AsH ₃ , PH ₃ , TMIn and TEGa into the reactor is stopped.

Thereafter, as shown in e to q of FIG. 2, the InAs quantum dots 4 and the In _x Ga _{1 -y} As _y P _{1 -y} barrier layers 6 are alternately and repeatedly formed. _{x Ga 1-y As y P} 1-y barrier layers 6 was formed by three layers, further formed uppermost InAs quantum dots 4. Thereby, the number of layers of the InAs quantum dots 4 is set to five.

The multiple In _x Ga _1-y As _y P _1-y barrier layers 6 are formed under the same conditions, and the multiple InAs quantum dots 4 are formed under the same conditions.
That is, before the InAs quantum dots 4 are formed, the supply of TMIn, TEGa, AsH ₃ , and PH ₃ is stopped in the reactor, and then the state in which H ₂ is supplied is maintained for about 10 seconds. For 10 seconds. Further, 5 seconds after the supply of TEAl is stopped, AsH ₃ is supplied into the reactor for 1 second, and AsH ₃ and TMIn are supplied into the reactor to form InAs quantum dots 4.

  Here, the number of layers of the InAs quantum dots 4 is described as five, but the number is not limited to five.

When the number of layers of InAs quantum dots 4 reaches the target as shown in n of FIG. 2, AsH ₃ was supplied to the reactor for 10 seconds after the formation of InAs quantum dots 4 as shown in m of FIG. After that, a second SCH layer 7 is formed on the uppermost InAs quantum dots 4 as indicated by n and r in FIG. As the second SCH layer 7, an In _x Ga _1-y As _y P _1-y layer is formed to a thickness of, for example, 100 nm. The In _x Ga _1-y As _y P _1-y layer is formed under the same conditions as the In _x Ga _1-y As _y P _1-y barrier layer 6, for example.
As a result, the active layer 8 having the multilayer structure of the quantum dots 4 is formed on the n-type InP buffer layer 2 as shown in FIG. 1D.

Next, a process for forming the structure shown in FIG. 1E will be described.
After the formation of the active layer 8, PH ₃ , TMIn, and DEZn are introduced as growth source gases into the reactor, so that the first p-type InP cladding layer 9 is formed on the second SCH layer 7, for example, about It is formed to a thickness of 200 nm. In this case, the gas flow rate is adjusted so that the doping concentration of zinc, which is a p-type impurity, is 5.0 × 10 ¹⁷ cm ⁻³ .

  Subsequently, after taking out the n-type InP substrate 1 from the reactor of the MOCVD apparatus, a dielectric, for example, a silicon oxide film 10 is formed on the first p-type InP clad layer 9. Further, a photoresist (not shown) is applied on the silicon oxide film 10, and this is exposed and developed to form a resist pattern. The resist pattern is formed in a stripe planar shape covering the optical waveguide region.

  Further, the silicon oxide film 10 in the region not covered with the resist pattern is etched by reactive ion etching (RIE) to form a stripe-shaped mask in the waveguide region. In this case, a fluorine-based gas is used as an etching gas for the silicon oxide film 10.

  Next, as shown in FIG. F, the silicon oxide film is etched by RIE from the p-type InP cladding layer 9 to the upper part of the n-type InP substrate 1 in a region not covered with the silicon oxide film 10 as a mask. The layer below 10 is formed in a striped mesa shape, and recesses 1a are formed on both sides thereof. In this case, chlorine gas is used as the etching gas.

With the resist pattern removed, the n-type InP substrate 1 is put into the reactor of the MOCVD apparatus, and TMIn, PH ₃ and DEZn are supplied into the reactor. Thus, as shown in FIG. 1G, the p-type InP buried layer 11 is selectively formed in the recess 1a on the n-type InP substrate 1 to a thickness that reaches the upper surface of the first p-type InP cladding layer 9. .

Subsequently, the supply of TMIn, PH ₃ and DEZn is stopped, and after a predetermined time has elapsed, TMIn and SiH ₃ are supplied into the reactor, whereby the n-type InP block layer is formed on the p-type InP buried layer 11. 12 is formed.

Thus, pn junction buried structures formed of the p-type InP buried layer 11 and the n-type InP block layer 12 are formed on both sides of the mesa shape including the active layer 8 having the quantum dots 4.
Thereafter, the n-type InP substrate 1 is taken out of the reactor, and the silicon oxide film 10 is removed by wet etching or dry etching.

Next, steps required until a structure shown in FIG. 1H is formed will be described.
First, the n-type InP substrate 1 is put into the reactor of the MOCVD apparatus, TMIn, PH ₃ , DEZn are supplied into the reactor, and the n-type InP block layer 11 and the first p-type InP cladding layer 9 are placed on the first layer. Two p-type InP cladding layers 13 are formed.

Subsequently, after the supply of PH ₃ , TMIn, and DEZn to the reactor is stopped, TMIn, TEGa, AsH _3, and DEZn are introduced into the reactor after a while. Thereby, the p-type InGaAs contact layer 14 is formed on the second p-type InP cladding layer 13.

Further, after taking out the n-type InP substrate 1 from the reactor, for example, Au / Zn / Au is sequentially formed on the p-type contact layer 14 as a p-side electrode 15 by vapor deposition. Further, AuGe / Au is formed as the n-side electrode 16 on the lower surface of the n-type InP substrate 1 by vapor deposition.
Thereby, a semiconductor laser is formed.

As described above, according to the present embodiment, before supplying the raw material for forming InAs quantum dots 4, that is, TMIn and AsH _3, to the reactor, the first SCH layer 3 or the barrier layer 6 serving as the base is used. TEAl is supplied to the surface of a certain In _x Ga _1-y As _y P _1-y layer, for example, corresponding to 1 ML for a certain period of time.

  The InAs quantum dots 4 formed under such conditions have a planar shape as shown in FIG. 3, and the size in the [−110] direction is smaller than the conventional size. The size in the [−110] direction and the size in the [110] direction are The size is almost the same and a symmetrical shape is obtained. Specifically, the quantum dot of FIG. 3 has a length of about 20 nm in both the [−110] direction and the [110] direction.

On the other hand, under the condition that TEAl is not supplied into the reactor before the InAs quantum dots are formed, the quantum dots 21 have an elliptical asymmetric shape as shown in FIG. Specifically, the quantum dots 21 shown in FIG. 4 have a length of about 30 nm in the [−110] direction and a length of about 20 nm in the [110] direction.
3 and 4 are drawn by extracting some of the quantum dots 4 and 21 of the atomic microscope (AFM) image.

The symmetrical InAs quantum dots 4 are formed for the following reason.
In the above-described embodiment, PH ₃ that is a group V material is removed from the reactor before the InAs quantum dots 4 are formed. For this reason, the TEAl supplied thereafter becomes an Al element atmosphere as shown in FIG. 1B because the organic side chain is decomposed on the surface of the In _x Ga _1-y As _y P _1-y layer. The Al element has a low vapor pressure and does not combine with the group V element and floats on the surface of the In _x Ga _1-y As _y P _1-y layer.

Thereafter, the supply of TEAl to the reactor is stopped, and after the TEAl is removed from the reactor by H ₂ , AsH ₃ and TMIn which are the raw materials of the InAs quantum dots 4 are supplied to the reactor. At that time, the Al element remains floating on the surface of the In _x Ga _1-y As _y P _1-y layer.

On the other hand, TMIn tries to migrate the surface in the [−110] direction by decomposing organic side chains on the surface of the In _x Ga _1-y As _y P _1-y layer to become In atoms. However, the Al element floating on the surface of the In _x Ga _1-y As _y P _1-y layer suppresses migration of the In element and acts as an anti-surfactant.

  As a result, the movement of In in the [−110] direction is suppressed, so that the InAs generated by the reaction are quantum dots having substantially the same size in the [−110] direction and the [110] direction. As a result, symmetrical InAs quantum dots 4 as shown in FIG. 3 are formed.

  On the other hand, when TEAl is not supplied before the InAs quantum dots are formed, the In element is likely to move in the [−110] direction, and as shown in FIG. A shaped quantum dot 21 is formed.

That is, the organic side chain of TMIn on the surface of the In _x Ga _1-y As _y P _1-y layer is decomposed into In atoms and migrates on the surface. In such a state, the quantum dots are finally formed by staying in a stable position in terms of energy, but when there is no supply immediately before the Al element, as described above, the anisotropy of the migration length of In atoms As a result, an asymmetrical quantum dot extending in the [−110] direction is formed.

When a symmetrical InAs quantum dot 4 formed according to this embodiment is applied to a quantum dot that emits light in the 1.55 μm band, which is a long-range optical communication wavelength band, the ground level is the energy band of FIG. As shown in the conduction band of the structure, the energy interval E ₁ of the first higher order level is about 70 meV. Therefore, according to the present embodiment, it is possible to form quantum dots having a large energy interval of about 10 meV as compared with about 60 meV of asymmetrical quantum dots in the prior art.

  As a result, it is possible to reduce the escape of electrons from the ground level to the first excitation level or higher at a high temperature, so that a decrease in gain can be suppressed, and operating characteristics of semiconductor lasers, optical amplifiers, etc. at high temperatures. Can be improved. For example, the increase rate of the threshold for a temperature of about 85 ° C. in a semiconductor laser can be reduced by about 15%, and the reduction rate of the optical gain for a temperature of about 85 ° C. in a semiconductor optical amplifier can be improved by about 15%. It becomes possible.

  In the above description, TEAl is used as the Al material to be supplied immediately before, but various Al materials such as trimethylaluminum (TMAl) and triisobutylaluminum (TIBAl) may be used.

  Further, the Al raw material supplied to the reactor immediately before supplying the raw material for forming InAs quantum dots 4 is not limited to supplying any of the above-mentioned gases alone, and the above Al Two or more types of raw materials, for example, TEAl and TMAl may be supplied into the reactor at the same time.

In the present embodiment, In _x Ga _1-y As _y P _1-y is used as a base layer for InAs quantum dots.
X is 0.85 and y is 0.33. However, x may be in a relationship of 0 ≦ x ≦ 1, and y may be in a relationship of 0 ≦ y ≦ 1.

In addition, the various growth parameters shown in the above embodiments have different application ranges depending on each growth apparatus, and can be arbitrarily changed. As growth parameters, for example, the supply amount of the Al raw material before the quantum dots 4 are formed, or the supply of the group V or group III source gas to the reactor immediately before the supply of the Al-containing gas is stopped in an H ₂ atmosphere. Time to stop growth. Furthermore, it is the growth interruption time in the H ₂ atmosphere after supplying the Al-containing gas, or the supply time of AsH ₃ supplied to form quantum dots, or supplied to form quantum dots. The amount of TMIn supplied, or the supply time of AsH ₃ after quantum dot growth can be mentioned.

In the present embodiment, the growth temperature of the quantum dots is not limited to 450 ° C., and may be any growth temperature at which quantum dots can be formed.
Furthermore, in the above embodiment, after supplying TEAl immediately before the formation of the quantum dots, the interruption of growth was introduced in the H ₂ atmosphere for 5 seconds for the purpose of removing TEAl from the reactor. On the other hand, for example, in the growth method such as the reduced pressure MOVPE method with a pressure of 10 Torr or less and the ultra high vacuum CVD (UHV-CVD) method, the flow rate of the raw material is high, so the processes of h and i in FIG. 2 are omitted. Therefore, the growth need not be interrupted in an H ₂ atmosphere.

Further, the growth temperature of the In _x Ga _1-y As _y P _1-y layer serving as the base of the quantum dots is not limited to 470 ° C., but the quaternary In _x Ga _1-y As _y P _1-y is used. It may be a temperature range in which growth is possible.

Furthermore, in this embodiment, the In _x Ga _1-y As _y P _1-y barrier layer 6 having a thickness of 40 nm is formed to a thickness of 40 nm, and the number of periods of the InAs quantum dots 4 is set to 5. May be arbitrarily changed according to the device design.

  Various growth raw materials may be used in addition to the growth raw material used in the above embodiment. For example, as a group III material, triethylindium (TEIn) may be used instead of TMIn, and trimethylgallium (TMGa) may be used instead of TEGa.

Tertiary butylarsine (TBAsH ₃ ), which is an organic metal raw material, is used instead of AsH ₃ as a raw material for the group V arsenic and phosphorus, and tertiary butyl phosphine (TBPH), which is an organic metal raw material, is used instead of PH _{3. 3} ) may be used.

In the above embodiment, the InAs quantum dots 4 are formed as the quantum dots in the active layer 8, but ternary mixed crystal InGaAs or InAsSb quantum dots may be used. InGaAsSb may also be used. That is, the quantum dot is formed from In _a Ga _1-a As _b Sb _1-b (0 ≦ a ≦ 1, 0 ≦ b ≦ 1). For example, triethylantimony (TESb) or trimethylantimony (TMSb) is used as a raw material for antimony.

  In this case, a hydrogen compound gas or organometallic raw material containing at least one of As element or antimony (Sb) element and an organometallic raw material containing at least one of In element or Ga element may be supplied simultaneously. . Alternatively, a hydride gas containing at least one of the As element and the Sb element or an organometallic raw material is supplied, and thereafter, an organometallic raw material containing at least one of the In element and the Ga element and the As element or the Sb element. You may supply simultaneously the hydrogen compound gas or organometallic raw material containing at least one.

In the above embodiment, an n-type InP substrate is used. However, a p-type InP substrate whose main surface is a (001) surface or a high resistance (SI) InP substrate whose main surface is a (001) surface is applied. May be. In that case, the above-described embedding structure and the like are arbitrarily changed.
Carrier gas mentioned above is not limited to H _2, instead of or in combination with helium H ₂ (He), may be used an inert gas such as argon (Ar).

  All examples and conditional expressions given here are intended to help the reader understand the inventions and concepts that have contributed to the promotion of technology, such examples and It should be construed without being limited to the conditions, and the organization of such examples in the specification is not related to showing the superiority or inferiority of the present invention. Although embodiments of the present invention have been described in detail, it should be understood that various changes, substitutions and variations can be made thereto without departing from the spirit and scope of the present invention.

Next, features of the embodiment of the present invention will be described.
(Supplementary Note 1) Forming an In _x Ga _1-y As _y P _1-y layer (0 ≦ x ≦ 1, 0 ≦ y ≦ 1) above the InP substrate in a growth atmosphere, and growing the aluminum source A quantum dot forming gas comprising a step of supplying to the atmosphere, a step of stopping the supply of the aluminum material to the growth atmosphere, and at least one of an arsenic material and an antimony material and at least one of an indium material and a gallium material. By supplying to the growth atmosphere, In _a Ga _1-a As _b Sb _1-b (0 ≦ a ≦ 1, 0 ≦ b ≦ 1) is formed on the In _x Ga _1-y As _y P _1-y layer. And a step of forming quantum dots.
(Additional remark 2) The manufacturing method of the optical semiconductor device of Additional remark 1 which has the process of supplying only carrier gas in the said growth atmosphere, after stopping supply of the said aluminum raw material.
(Supplementary Note 3) The _{an In} x _Ga to _1-y As _y after _{P 1-y} layer is formed, the method for manufacturing the optical semiconductor device according to Supplementary Note 1 or 2 having the step of flowing only the carrier gas into the growth atmosphere .
(Additional remark 4) The said carrier gas is either hydrogen or an inert gas, The manufacturing method of the optical semiconductor device of Additional remark 2 or Additional remark 3 characterized by the above-mentioned.
(Additional remark 5) Before supplying the said aluminum raw material, the supply of a group III raw material is stopped in the said growth atmosphere, a phosphine and carrier gas are supplied, and it has the process of setting a heater to the growth temperature of the said quantum dot. The manufacturing method of the optical semiconductor device as described in any one of thru | or appendix 4.
(Additional remark 6) Before supplying the said gas for forming a quantum dot to the said growth atmosphere, it has the process of supplying the raw material gas containing at least one of an arsenic element or an antimony element to the said growth atmosphere. The optical semiconductor device according to any one of appendix 5.
(Supplementary Note 7) The _{In x Ga 1-y As y} P 1-y layer manufacturing method of the optical semiconductor device according to any one of Appendices 1 to Appendix 5 is formed on the (001) plane.
After forming the (Supplementary Note 8) The quantum dot to form a second _{In x Ga 1-y As y} P 1-y layer (0 ≦ x ≦ 1,0 ≦ y ≦ 1) on the quantum dot The method for manufacturing an optical semiconductor device according to any one of Appendix 1 to Appendix 6, which includes a process.
(Supplementary Note 9) In _x Ga _1-y As _y P _1-y layer (0 ≦ x ≦ 1, 0 ≦ y ≦ 1) formed above the InP substrate, and the In _x Ga _1-y As _y P _The aluminum element remaining on the _1-y layer and In _a Ga _1-a As _b Sb _1-b (0 ≦ a ≦ 1, formed on the In _x Ga _1-y As _y P _1-y layer) An optical semiconductor device having quantum dots of 0 ≦ b ≦ 1).

1 n-type InP substrate 2 n-type InP buffer layer 3 first SCH layer 4 InAs quantum dots 6 In _x Ga _1-y As _y P _1-y barrier layer 7 second SCH layer 8 active layer 9 first p Type InP cladding layer 10 silicon oxide film 11 p-type InP buried layer 12 n-type InP blocking layer 13 second p-type InP cladding layer 14 p-type InGaAs contact layer 15 p-side electrode 16 n-side electrode

Claims (5)

Forming an In _x Ga _1-y As _y P _1-y layer (0 ≦ x ≦ 1, 0 ≦ y ≦ 1) above the (001) plane of the InP substrate in a growth atmosphere;
Supplying an aluminum raw material to the growth atmosphere;
Stopping the supply of the aluminum raw material to the growth atmosphere;
By supplying a gas containing at least one of an arsenic raw material and an antimony raw material and at least one of an indium raw material and a gallium raw material to the growth atmosphere, an In _x Ga _1-y As _y P _1-y layer is formed on the In _x Ga _1-y As _y P _1-y layer. forming a quantum dot of _{a Ga 1-a as b Sb} 1-b (0 ≦ a ≦ 1,0 ≦ b ≦ 1),
The manufacturing method of the optical semiconductor device which has this.   The method for manufacturing an optical semiconductor device according to claim 1, further comprising a step of supplying only a carrier gas into the growth atmosphere after the supply of the aluminum raw material is stopped. 3. The manufacturing of the optical semiconductor device according to claim 1, further comprising a step of temporarily flowing only a carrier gas into the growth atmosphere after forming the In _x Ga _1-y As _y P _1-y layer. Method. 2. The method according to claim 1, further comprising a step of stopping supply of the group III material in the growth atmosphere, supplying phosphine and a carrier gas, and setting a heater to the growth temperature of the quantum dots before supplying the aluminum material. 4. The method of manufacturing an optical semiconductor device according to claim 3. An In _x Ga _1-y As _y P _1-y layer (0 ≦ x ≦ 1, 0 ≦ y ≦ 1) formed above the (001) plane of the InP substrate;
An aluminum element remaining on the In _x Ga _1-y As _y P _1-y layer;
In _a Ga _1-a As _b Sb _1-b (0 ≦ a ≦ 1, 0 ≦ b ≦ 1) quantum dots formed on the In _x Ga _1-y As _y P _1-y layer;
An optical semiconductor device.

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