JP4006055B2 - Compound semiconductor manufacturing method and compound semiconductor device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a compound semiconductor device having a III-V group compound semiconductor containing both N and As as group V elements, and a method for manufacturing the compound semiconductor.
[0002]
[Prior art]
In recent years, as a new material system that greatly expands the field of use of III-V compound semiconductors as optoelectronic materials, III-V compound mixed crystal semiconductors containing both N (nitrogen) and As (arsenic) as group V elements Materials have been proposed and attracted attention. AlGaN with large N composition_xAs_1-xSince the (x = 0.2) mixed crystal may be a direct transition semiconductor material lattice-matched to the Si substrate, it is a light source material for opto-electronic integrated circuits, and GaInN with a small N composition._yAs_1-yThe (y = 0.015-0.035) mixed crystal is obtained by lattice-matching a direct transition semiconductor material having a band gap corresponding to wavelengths of 1.3 μm and 1.55 μm, which are important for optical fiber communication, to a GaAs substrate. These are detailed in Applied Physics Journal Vol. 65, 1996, No. 2, page 148 (Reference 1).
[0003]
In particular, in the latter, a large band offset can be obtained between the active layer and the clad layer by using the GaInNAs mixed crystal for the active layer and an AlGaAs or GaInP compound semiconductor for the clad layer. It is proved to be a material system that realizes a semiconductor laser for communication whose temperature characteristics are remarkably improved as compared with semiconductor lasers in the region, and is particularly noteworthy in practical use.
[0004]
More specifically, in Electronic Letters, 1996, Vol. 32, page 1585 (reference 2), Ga_0.75In_0.25N_0.005As_0.995Is used for the well layer of a single quantum well active layer, and lasing at a wavelength of 1.113 μm at 77K has been reported. The active layer including the layer made of GaInNAs in this conventional example is manufactured by molecular beam epitaxy (MBE), and radical-excited N molecular beams are used as N raw materials. A GaAs (001) plane is used for the substrate, and the crystal is grown at a substrate temperature of 500 ° C.
[0005]
[Problems to be solved by the invention]
The conventional example described above is laser oscillation at a wavelength of 1.113 μm, and laser oscillation at wavelengths of 1.3 μm and 1.55 μm, which are important for optical fiber communication, has not been achieved. In order to obtain a GaInNAs mixed crystal having band gaps corresponding to wavelengths of 1.3 μm and 1.55 μm by lattice matching with GaAs, the composition is set to Ga for a wavelength of 1.3 μm._0.928In_0.072N_0.025As_0.975Ga for 1.55 μm_0.904In_0.096N_0.034As_0.966And it is sufficient. That is, it is necessary to make the composition ratio of N larger (0.025 or more) than the conventional example shown in Reference Document 2.
[0006]
As a result of intensive experiments by the inventors of the present application, in the GaInNAs mixed crystal produced by the conventional method, the crystal quality greatly deteriorates as the composition of N increases, and the wavelength becomes 1.3 μm or 1.55 μm. It has been found that a GaInNAs crystal having a corresponding band gap does not have sufficient crystallinity and light emission characteristics to be used as an active layer of a semiconductor laser. Journal of Electronic Materials, 1995, Vol. 24, p.263 (reference 3) describes GaAs_0.8N_0.2As estimated from the fact that it is reported that phase separation into GaAs and GaN is attempted even if a crystal having a composition of 1 is made, the As compound and the N compound have an essentially stable mixed crystal system. It is thought that the cause is not to make. That is, the GaInNAs mixed crystal required for laser oscillation at wavelengths of 1.3 μm and 1.55 μm as described above has a Ga-In-As that has an N composition that is about an order of magnitude smaller than the reported example of Reference 3. -N quaternary mixed crystal system is considered to have a composition corresponding to an immiscible region (miscibility gap), and microscopically, a non-uniform composition distribution localized in a region of N compound and a region of As compound Tend to have a large number of crystal defects. Therefore, sufficient crystallinity and light emission characteristics for use as an active layer of a semiconductor laser cannot be obtained.
[0007]
The present invention aims to solve the above problems. In other words, in a III-V compound semiconductor mixed crystal containing both As and N as group V elements, a mixed crystal having a uniform composition distribution while maintaining good crystallinity even in a composition corresponding to the non-miscible region. A method of crystal growth that can be produced is provided. In particular, the present invention provides a manufacturing method for obtaining a group III-V compound semiconductor mixed crystal (particularly a GaInNAs mixed crystal) containing both As and N having band gaps corresponding to wavelengths of 1.3 μm and 1.55 μm. It is another object of the present invention to provide a compound semiconductor device capable of obtaining sufficient crystallinity and light emission characteristics.
[0008]
[Means for Solving the Problems]
  Moreover, the manufacturing method of the compound semiconductor which concerns on Claim 1 of this invention is as follows.
  A method for producing a compound semiconductor, wherein a laminated structure including one or more III-V compound semiconductor crystals containing both N (nitrogen) and As (arsenic) as group V elements is formed on a semiconductor substrate,
  The semiconductor substrate is composed of a zinc blende type semiconductor crystal, andThe surface having the Miller index (001) is inclined in the direction index <1-10> direction.With an inclined surface,
  The group III-V compound semiconductor crystal containing both N and As as the group V element has a composition ratio of [N atom density] / ([N atom density] + [ As atom density]) is 0.025 or more,
  The zincblende type semiconductor crystal used as the semiconductor substrate is made of GaAs.To achieve the above objective.
  In addition, the {111} B plane direction in the present specification refers to the normal direction of the {111} B plane. In this specification, the direction of a surface refers to the normal direction of the surface.
[0009]
The inventors changed the viewpoint from the conventional method for examining crystal growth described above, and examined the state of the surface of the substrate used. As a result, the step density on the substrate surface and the type of atoms terminating the step end have a great effect on the growth of III-V compound semiconductor mixed crystals containing both As and N as group V elements. I found out. In the present invention according to claim 1, since the substrate surface has a step terminated with a group V element, a III-V group compound semiconductor mixed crystal containing both As and N having a uniform composition and good crystallinity is formed. Can be produced.
[0010]
A method for producing a compound semiconductor according to claim 2 of the present invention includes:
  SaidBoardThe surface having the Miller index (001) is inclined in the direction index <1-10> direction at an angle of 3 degrees or more and 30 degrees or less.The above objective is achieved by having an inclined surface.
[0011]
In the method for producing a compound semiconductor according to a third aspect of the present invention, the stacked structure is achieved by crystal growth at a temperature of 600 ° C. or higher and 750 ° C. or lower.
[0012]
By appropriately selecting the temperature for crystal growth, the above-mentioned actions and effects can be obtained particularly effectively.
[0013]
This inventionConversionIn the compound semiconductor manufacturing method, the group III-V compound semiconductor crystal containing both N and As as the group V element has a composition ratio of [N atom density] / N contained in the crystal as the group V element. ([N atom density] + [As atom density])
The above-mentioned object is achieved by having 0.025 or more.
[0014]
By applying this invention to a III-V compound semiconductor mixed crystal containing both As and N containing N above a certain value, a remarkable effect can be obtained.
[0015]
This inventionConversionThe compound semiconductor manufacturing method achieves the above object by forming a zinc blende type semiconductor crystal used as a substrate from GaAs.
[0016]
By using GaAs as the substrate, a group III-V compound semiconductor mixed crystal containing both As and N as group V elements corresponding to wavelengths 1.3 μm and 1.55 μm, which are important for optical fiber communications, is obtained by lattice matching. be able to.
[0017]
Claims of the invention4According to the method for manufacturing a compound semiconductor, a compound semiconductor containing P (phosphorus) as a group V element is stacked, and a compound semiconductor having only As as a group V element is stacked on at least one molecular layer to 10 molecular layers. Further, the above object is achieved by including a step of growing a III-V group compound semiconductor crystal containing both N and As as group V elements.
[0018]
By performing this step, the interface between the P compound and the III-V group compound semiconductor mixed crystal containing both N and As as group V elements becomes steep.
[0019]
Claims of the invention5The method for producing a compound semiconductor according to the present invention achieves the above object by including a step of supplying only an N raw material immediately before crystal growth of a group III-V compound semiconductor crystal containing both N and As as group V elements. To do.
[0020]
By performing this step, the surface of the base is nitrided immediately before crystal growth of the III-V compound semiconductor mixed crystal containing both N and As as group V elements. The III-V compound semiconductor mixed crystal including the substrate starts smooth step flow growth from the beginning of crystal growth.
[0021]
Claims of the invention6The compound semiconductor device according to
A compound semiconductor device having a stacked structure including at least one group III-V compound semiconductor crystal containing both N (nitrogen) and As (arsenic) as group V elements on a semiconductor substrate,
  A surface on which the semiconductor substrate is made of zinc blende type semiconductor crystal and a group III-V semiconductor is laminatedofThe direction isThe surface having the Miller index (001) is inclined so as to incline in the direction index <1-10> direction,
  The group III-V compound semiconductor crystal containing both N and As as the group V element has a composition ratio of [N atom density] / ([N atom density] + [ As atom density]) is 0.025 or more,
  The zincblende type semiconductor crystal used as the semiconductor substrate is made of GaAs.It is characterized by that.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
(Embodiment 1) As Embodiment 1 of the present invention, a double heterostructure made of AlGaAs / GaInNAs / AlGaAs is formed on a GaAs substrate inclined from the (001) plane toward the (111) B plane using the MBE method. The case of manufacturing will be described.
[0023]
A GaAs substrate having a surface inclined from the (001) plane toward the (111) B plane is prepared, and an Al molecular beam, a Ga molecular beam, an In molecular beam, As₂A multilayer film of a compound semiconductor was grown by MBE using a molecular beam or radical-excited N molecular beam as a raw material.
[0024]
Here, the “surface inclined from the (001) plane toward the (111) B plane” is an inclined substrate of the (001) plane and is cut out with an inclination so that the surface has a step end terminated with As atoms. Substrate. A substrate inclined by 55 ° from the (001) plane toward the (111) B plane is the (111) B plane. The {111} B plane is also called a {111} As plane, and the {111} A plane is also called a {111} Ga plane.
[0025]
The structure of the produced multilayer film is as follows. First, a buffer layer made of GaAs having a layer thickness of 0.5 μm is formed on a GaAs substrate, and an Al layer having a layer thickness of 0.5 μm is formed thereon._0.2Ga_0.8A first barrier layer made of As and a Ga layer having a layer thickness of 0.1 μm thereon_0.928In_0.072N_0.025As_0.975A light emitting layer made of Al with a thickness of 0.5 μm thereon_0.2Ga_0.8On the second barrier layer made of As, GaAs having a layer thickness of 0.5 μm is formed as a protective layer. Ga at this time_0.928In_0.072N_0.025As_0.975The crystal is a GaInNAs crystal lattice-matched to GaAs and having a band gap corresponding to a wavelength of 1.3 μm. The crystal growth temperature was maintained at 650 ° C. during the production of the multilayer film, and the crystal growth rate was 0.5 μm / hour.
[0026]
The crystal growth by the MBE method was performed in the sequence shown in FIG. FIG. 1A shows the substrate temperature, and FIGS. 1B to 1F show the shutter sequences of the respective molecular beams. That is, after introducing the GaAs substrate into the MBE crystal growth apparatus, (Process A) As₂While irradiating with a molecular beam, the temperature is raised to 650 ° C. to obtain a clean surface of GaAs. Then, (Process B) Ga molecular beam, As₂Crystal growth of GaAs with a layer thickness of 0.5 μm by molecular beam, followed by (Step C) Al molecular beam, Ga molecular beam, As₂Al with a thickness of 0.5 μm by molecular beam_0.2Ga_0.8Get As. Next, (step D) after supplying only N radical molecular beam and replacing a part of As atoms forming the step end of the growth layer outermost surface with N atom by nitriding, (step E) Ga molecular beam, In molecule Line, As₂A GaInNAs layer having a layer thickness of 0.1 μm is obtained by molecular beam or N radical molecular beam. Again (Process F) Al molecular beam, Ga molecular beam, As₂Al with a thickness of 0.5 μm by molecular beam_0.2Ga_0.8Finally, (Step G) Al molecular beam is stopped to obtain 0.5 μm GaAs. The intensity of each molecular beam during crystal growth of each layer was adjusted so as to be optimum for each layer.
[0027]
FIG. 2 shows the result of measuring the photoluminescence spectrum of only a sample GaInNAs layer prepared on a substrate having an inclination angle of 5 °, which was excited using a YAG laser at room temperature. FIG. 2A shows a case where a (001) substrate inclined by 5 ° is used, and FIG. 2B shows a case where a (001) substrate not inclined is used. Compared to the PL intensity of the sample prepared on the non-tilted (001) plane shown at the same time, a reduction in half-value width and an increase in emission intensity were confirmed, and a high-quality GaInNAs mixed crystal with few crystal defects was obtained. I was able to. Further, the obtained film had no compositional nonuniformity, and the surface condition was extremely smooth and good.
[0028]
FIG. 3 shows the inclination angle dependence of the PL intensity of the GaInNAs layer fabricated on the inclined substrate. For comparison, the same structure is produced on a GaAs substrate having a surface inclined from the (001) plane toward the (111) A plane, and is shown in FIG. In a sample grown on a substrate having a surface inclined from the {001} plane toward the {111} B plane, the emission intensity increases with the inclination angle and takes the maximum value. On the other hand, when a crystal is grown on a substrate having a surface inclined in the {111} A plane direction, the crystallinity is slightly improved due to the effect of step flow growth in a region where the inclination angle is small, but the inclination As the angle increases, the PL emission intensity decreases rather than when there is no inclination. As in the present invention, it is found that the crystallinity of a GaInNAs crystal is remarkably improved by growing a GaInNAs crystal on a GaAs substrate having a surface inclined from the {001} plane toward the {111} B plane.
[0029]
A III-V compound semiconductor mixed crystal containing both As and N having an unstable composition corresponding to the immiscible region on a substrate having a plane orientation not inclined from the {001} plane as in the prior art. In the case of crystal growth, island-like growth occurs microscopically, and a stable composition of an As compound or N compound starts to grow independently on each small crystal island and tends to cause phase separation locally. . As a result, the quality of the crystal viewed macroscopically is not good. On the other hand, when a substrate having a surface with a step end terminated with a group V element, that is, a substrate with a surface inclined from the {100} plane toward the {111} B plane, the step end becomes stable with a group V element. Therefore, the As source and N source attached to the substrate during crystal growth reach the step end regardless of the atomic species and are taken into the group V site as they are. As a result, the ratio of As and N incorporated into the step end is determined by the supply amount of As source and N source regardless of the stability of the crystal, and therefore, III-V containing both As and N having a uniform composition. Group crystal semiconductor mixed crystals can be obtained with good crystallinity. Thus, by using a substrate having a surface step terminated at a group V site, As and N having uniform and good crystallinity without causing phase separation even in a composition corresponding to the immiscible region. A new effect has been found that makes it possible to produce a III-V compound semiconductor mixed crystal containing both of.
[0030]
With respect to the angle of the inclined substrate, a sufficient effect appears at 3 to 30 ° as seen in FIG. 3, and it is more preferably set to 5 to 15 °. When the tilt angle is small, the step density is low, so that the effect does not appear remarkably. When the tilt angle is too large, the crystallinity deteriorates.
[0031]
FIG. 4 shows the dependence of the PL intensity on the substrate temperature during crystal growth when a multilayer structure is formed on a GaAs substrate having a surface inclined by 10 ° from the (001) plane to the (111) B plane. . All of these are PL intensities of GaInNAs crystals having a band gap corresponding to a wavelength of 1.3 μm with a composition lattice-matched to GaAs. The PL intensity is normalized by the value of the sample with a substrate temperature of 700 ° C. A sample with strong emission intensity is obtained at a substrate temperature of 600 ° C. to 750 ° C., and it can be seen that the range of ΔT shown in FIG. 4 is the optimum crystal growth temperature range. When the temperature of crystal growth is low, step flow growth in which crystal growth occurs from the end of the step is difficult to occur, and when the crystal growth temperature is high, group V elements once incorporated into the crystal are re-evaporated, which is good. Crystal growth does not occur.
[0032]
As shown in FIG. 1, just before the crystal growth of the GaInNAs layer, only the N radical molecular beam is supplied and the underlying Al_0.2Ga_0.8A part of As atoms forming the step edge on the outermost surface of the As layer was replaced with N atoms (process D), and then crystal growth of the GaInNAs layer was started (process E). When a part of As atoms on the substrate surface is first substituted with N atoms, the subsequent growth of the III-V compound semiconductor mixed crystal containing both As and N becomes homoepitaxial growth, resulting in step flow growth. The initial crystal growth starts smoothly and the quality of the crystal produced thereon is improved.
[0033]
In particular, when a GaInNAs layer thinner than the electron de Broglie wavelength is grown as a quantum well layer, it has been found that the quantum effect generated at that time is remarkably increased by adopting a step nitriding step (step D). When the nitriding step is not included, the As compound (Al_0.2Ga_0.8It is thought that the quantum effect is reduced because the interface with the III-V compound semiconductor mixed crystal (GaInNAs) containing both As), As, and N is not rapidly switched. By introducing a nitriding step at the interface, the composition is rapidly switched and a good interface can be obtained.
[0034]
As described above, according to the present invention, a high quality GaInNAs mixed crystal could be obtained. Furthermore, when the above method was applied to the production of an active layer corresponding to a wavelength region of 1.3 μm to produce a semiconductor laser device, a high-performance laser was obtained.
[0035]
(Embodiment 2) As Embodiment 2 of the present invention, metal organic chemical vapor deposition (MO-CVD) is formed on a GaAs substrate inclined from the (001) plane toward the (111) B plane. A case where a single quantum well structure made of GaInP / GaInNAs / GaInP is fabricated using the method will be described.
[0036]
A GaAs substrate having a surface inclined from the (001) plane toward the (111) B plane is prepared, and trimethylgallium (TMG), trimethylindium (TMI), arsine (AsH) is formed thereon._Three), Phosphine (PH_Three), Dimethylhydrazine (DMeHy) as a source gas, hydrogen (H₂A compound semiconductor multilayer film was grown by MO-CVD using a carrier gas as a carrier gas.
[0037]
The structure of the produced multilayer film is as follows. First, a buffer layer made of GaAs having a thickness of 0.5 μm is formed on a GaAs substrate, and Ga is formed thereon._0.51In_0.49A first barrier layer made of P is formed on the Ga layer having a thickness of 8 nm._0.89In_0.11N_0.04As_0.96A single quantum well light-emitting layer made of GaGa having a layer thickness of 0.5 μm thereon_0.51In_0.49On the second barrier layer made of P, GaAs having a layer thickness of 0.5 μm is formed as a protective layer. Ga at this time_0.89In_0.11N_0.04As_0.96The crystal is a GaInNAs crystal lattice-matched to GaAs. Crystal growth was performed at normal pressure, the crystal growth temperature was maintained at 700 ° C. during the production of the multilayer film, and the crystal growth rate was 1 μm / hour.
[0038]
The crystal growth by the MO-CVD method was performed in the sequence shown in FIG. FIG. 5A shows the substrate temperature, and FIGS. 5B to 5F show the sequence of each source gas. That is, after introducing the GaAs substrate into the MO-CVD crystal growth apparatus, (Step I) AsH_ThreeAnd H₂The temperature is raised to 700 ° C. in the atmosphere of (3), and then (Process J) TMG, AsH_ThreeCrystal growth of GaAs with a thickness of 0.5 μm by (Step K) TMG, TMI, PH_ThreeGa layer with a layer thickness of 0.5 μm_0.51In_0.49Get P. Next (Process L) TMG and AsH_ThreeAnd crystal growth of 1 to 3 molecular layers of GaAs. (Process M) Only DMeHy is supplied to form part of As atoms forming the step edge on the outermost surface of the growth layer by nitriding with N atoms. After replacement, (Step N) TMG, TMI, AsH_Three, DMInHy obtains a GaInNAs layer having a thickness of 8 nm. Again (Step O) TMG and AsH_ThreeAnd crystal growth of 1 to 3 molecular layers of GaAs, (Process P) TMG, TMI, PH_ThreeGa with a layer thickness of 0.5 μm_0.51In_0.49P, and finally (process Q) TMG, AsH_ThreeThus, 0.5 μm of GaAs was obtained. The flow rate of each gas during crystal growth of each layer was adjusted so as to be optimal for each layer.
[0039]
For comparison, the same structure is fabricated on a GaAs substrate having a surface inclined from the (001) plane to the (111) A plane, and only the GaInNAs layer of each sample is excited using a YAG laser at room temperature. When the intensity of photoluminescence (PL intensity) was measured, the same result as that of the first embodiment shown in FIG. 3 was obtained, and 3-30 ° from the {001} plane to the {111} B plane direction, desirably It has been found that the crystallinity is remarkably improved by growing a GaInNAs crystal on a GaAs substrate having a surface inclined by 5 to 15 °. The dependence of the PL intensity on the substrate temperature during crystal growth was similar to that shown in FIG.
[0040]
As shown in FIG. 5, before the GaInNAs layer is crystal-grown on the underlying GaInP layer, an As compound of several molecular layers is grown (step L), and the step end of the outermost surface is formed. A part of As atoms to be replaced was replaced with N atoms (step M), and then crystal growth of the GaInNAs layer was started (step N). When the GaInNAs layer is directly crystal-grown on the P compound, the GaInNAs step flow growth hardly occurs at the initial stage of the crystal growth, and the effect using the tilted substrate tends not to be sufficiently exhibited. On the other hand, it has been found that the problem can be solved by starting crystal growth after a thin layer of the As compound is bound on the P compound. The thickness of the thin layer of the As compound is required to be at least one molecular layer or more, but is desirably 10 molecular layers or less so as not to affect the band lineup of the heterojunction between the P compound and the GaInNAs layer.
[0041]
Further, when a GaInNAs layer is grown on the As compound of the intermediate layer, a nitriding process is performed at the interface and a part of As atoms on the surface is replaced with N atoms. Since the growth of the III-V group compound semiconductor mixed crystal containing N together becomes homoepitaxial growth, step flow growth is likely to occur, the initial crystal growth is smoothly started, and the crystallinity of the growth layer thereon is improved. In addition, the switching of the composition of the III-V compound semiconductor mixed crystal containing both the As compound and As and N occurs abruptly.
[0042]
As described above, according to the present invention, a high quality GaInNAs mixed crystal could be obtained. Furthermore, when the above method was applied to the production of an active layer corresponding to a wavelength region of 1.55 μm to produce a semiconductor laser device, a high-performance laser device was obtained.
[0043]
(Embodiment 3) As Embodiment 3 of the present invention, GaInAs / GaNAs / is formed on a GaAs substrate inclined from the (001) plane toward the (111) B plane by using an organic metal MBE (MO-MBE) method. A case where a strain compensation quantum well structure made of GaInAs is manufactured will be described.
[0044]
A GaAs substrate having a surface inclined by 15 ° from the (001) plane toward the (111) B plane is prepared, and a trimethylgallium (TMG) molecular beam, a trimethylindium (TMI) molecular beam, As₂Molecular beam, diethylylamine (NH (C₂H_Five)₂) A compound semiconductor multilayer film was grown by MO-MBE using a molecular beam as a raw material.
[0045]
The structure of the produced multilayer film is as follows. First, a buffer layer made of GaAs having a thickness of 1.0 μm is formed on a GaAs substrate, and a Ga layer having a thickness of 10 nm is formed thereon._0.7In_0.3A first barrier layer made of As and having a compressive strain of + 2% and GaN having a thickness of 8 nm_0.03As_0.97GaAs having a layer thickness of 0.5 μm is formed as a protective layer on the triple quantum well structure composed of a quantum well light emitting layer having a tensile strain of −0.5%. The crystal growth temperature was maintained at 600 ° C. during the production of the multilayer film, and the crystal growth rate was 0.4 μm / hour. The obtained film was a single crystal film with no compositional uniformity and excellent emission characteristics.
[0046]
Furthermore, when a semiconductor laser device using GaNAs produced by the above method as an active layer was produced, a high-performance laser emitting light at a wavelength of 1.3 μm was obtained.
[0047]
(Embodiment 4) As Embodiment 4 of the present invention, AlGaNAs / GaNAs / is formed on a GaP substrate inclined from the (001) plane toward the (111) B plane by using metal organic chemical vapor deposition MO-CVD. A case where a single quantum well structure made of AlGaNAs is fabricated will be described.
[0048]
A GaP substrate having a surface inclined by 10 ° from the (001) plane toward the (111) B plane is prepared, and trimethylaluminum (TMA), trimethylgallium (TMG), arsine (AsH) is formed thereon._Three), Ammonia (NH_Three) As the source gas and H₂A multilayer film of a compound semiconductor was grown by MO-CVD using as a carrier gas.
[0049]
The structure of the produced multilayer film is as follows. First, an Al layer with a thickness of 0.5 μm is formed on a GaP substrate._0.2Ga_0.8N_0.2As_0.8A first barrier layer made of GaN having a thickness of 10 nm_0.2As_0.8A single quantum well light-emitting layer made of Al with a thickness of 0.5 μm is formed thereon._0.2Ga_0.8N_0.2As_0.8On the second barrier layer made of GaAs, GaAs having a layer thickness of 0.5 μm is formed as a protective layer. Each layer at this time has a mixed crystal composition that substantially lattice matches with GaP. Crystal growth was performed at 100 Torr, the crystal growth temperature was maintained at 750 ° C. during the production of the multilayer film, and the crystal growth rate was 0.3 μm / hour.
[0050]
As a result of evaluating the obtained film by X-ray diffraction, the full width at half maximum of the (400) diffraction spectrum was 15 seconds, which was a very good value. A single crystal film excellent in crystallinity with no non-uniform composition was obtained. Furthermore, when a semiconductor laser device using GaNAs produced by the above method as an active layer was produced, a high-performance laser was obtained.
[0051]
By the way, in all the embodiments shown so far, even if the inclination direction of the {001} substrate is deviated by about ± 10 ° in the {001} plane from the direction of the {111} B plane, the surface step is a group V element. The same effect was obtained because it ends with.
[0052]
Further, the substrate is not limited to GaAs or GaP as long as it is a zinc blende type semiconductor crystal, and similar effects were obtained with other III-V group semiconductors and II-VI group semiconductor crystals.
[0053]
In the above embodiment, the MBE method, the MO-MBE method, and the MO-CVD method have been described. As a group III material, a solid material, and as a group V material, AsH_ThreeThe same effect can be obtained by using a gas source MBE (GS-MBE) method using a gas or a chemical molecular beam epitaxy (CBE) method using an organometallic compound as a group III material and a gas material as a group V material. It was.
[0054]
In the above-described embodiment, a compound containing Ga, In, Al as the group III element and As, N as the group V element is shown. However, other group III elements (such as B) and group V elements (P, The same effect can be obtained even if an impurity element (Zn, Be, Mg, Te, S, Se, Si, etc.) is appropriately contained.
[0055]
In the description so far, the direction indicated as “up” indicates a direction away from the substrate, and “down” indicates a direction approaching the substrate. Crystal growth proceeds from “down” to “up”.
[0056]
The present invention is not limited to the combination of the crystal composition, the band gap wavelength, and the heterojunction shown in the above embodiment, but includes a group III-V compound semiconductor including both As and N having other compositions and band gaps. Needless to say, it can be applied to the production of crystals. In addition, the present invention is not limited to the case where the growth layer is lattice-matched to the substrate crystal. For example, a strain ratio of a mixed crystal having a lattice irregularity, such as a strained quantum well structure of a semiconductor laser, does not induce crystal defects. There may be.
[0057]
Moreover, it is possible to use a crystal growth method and materials other than those shown in the above specific examples. Especially for both MBE and CVD, radical excited N₂, NH_ThreeOr an organic nitrogen compound is desirable as the N source.
[0058]
Although the substrate is left in this embodiment mode, it goes without saying that the present invention is effective even if the substrate is removed by etching.
[0059]
【The invention's effect】
As described above, according to the method for producing a compound semiconductor according to the first aspect of the present invention, As and N having extremely uniform and good crystallinity are obtained without phase separation even in a composition corresponding to the immiscible region. A III-V compound semiconductor mixed crystal containing both can be produced. In particular, a III-V group compound semiconductor mixed crystal containing both As and N having band gaps corresponding to wavelengths of 1.3 μm and 1.55 μm and sufficient crystallinity to be used as an active layer of a semiconductor laser. It can be made.
[0060]
According to the method for producing a compound semiconductor according to the second and third aspects of the present invention, the effect of the second aspect can be obtained more suitably.
[0061]
Claims of the invention1According to the method for producing a compound semiconductor according to the present invention, a crystal having a large N composition, which cannot obtain a good crystal by the conventional crystal growth method, can be obtained.
[0062]
Claims of the invention1According to the method for producing a compound semiconductor according to the present invention, a III-V compound semiconductor mixed crystal containing both As and N having a uniform and good composition distribution having band gaps corresponding to wavelengths of 1.3 μm and 1.55 μm is obtained. High-quality light emission important for optical fiber communication using a III-V compound semiconductor mixed crystal containing both As and N prepared by the method of claims 1 to 4 It becomes possible to create an element.
[0063]
Claims of the invention4According to the method for producing a compound semiconductor according to the present invention, a smooth step flow growth occurs in the III-V compound semiconductor mixed crystal containing both As and N on the P compound from the initial stage of the crystal growth. Will improve.
[0064]
Claims of the invention5According to the method for producing a compound semiconductor, the III-V compound semiconductor mixed crystal containing both As and N on the surface of the compound semiconductor starts smooth step flow growth from the initial stage of crystal growth, and crystallinity is improved. To do. Further, the interface between the underlying As compound and the III-V compound semiconductor mixed crystal containing both As and N as group V elements is sharp enough to produce a quantum well structure.
[0065]
Claims of the invention6The compound semiconductor device according to the present invention has a III-V group compound semiconductor mixed crystal containing both As and N having extremely uniform and good crystallinity without phase separation even in a composition corresponding to the immiscible region. A compound semiconductor device with high performance can be provided. In particular, when the compound semiconductor device is applied to a light emitting element as a compound semiconductor device, a highly efficient compound semiconductor light emitting element can be provided.
[Brief description of the drawings]
FIG. 1 is a diagram showing a time chart of crystal growth in a first embodiment of the present invention.
FIG. 2 is a diagram showing a PL spectrum of a GaInNAs crystal produced in the first embodiment of the present invention.
FIG. 3 is a diagram showing the dependence of the PL intensity on the tilt angle and tilt direction of the substrate of the GaInNAs crystal fabricated in the first embodiment of the present invention.
FIG. 4 is a diagram showing the dependence of PL intensity on the substrate temperature of the GaInNAs crystal produced in the first embodiment of the present invention.
FIG. 5 is a diagram showing a time chart of crystal growth in a second embodiment of the present invention.

Claims (6)

A method for producing a compound semiconductor, wherein a laminated structure including one or more III-V compound semiconductor crystals containing both N (nitrogen) and As (arsenic) as group V elements is formed on a semiconductor substrate,
The surface of the semiconductor substrate made of zinc blende type semiconductor crystal and having a Miller index (001) is inclined so as to incline in the direction index <1-10> direction ,
The group III-V compound semiconductor crystal containing both N and As as the group V element has a composition ratio of [N atom density] / ([N atom density] + [ As atom density]) is 0.025 or more,
Method of producing a compound semiconductor of the zinc blende-type semiconductor crystal used as a semiconductor substrate and said GaAs Tona Rukoto. The substrate has a surface that is inclined such that a plane having a Miller index (001) is inclined in an angle of 3 degrees or more and 30 degrees or less in a direction index <1-10> direction. The method for producing a compound semiconductor according to claim 1.   The method for producing a compound semiconductor according to claim 1, wherein the stacked structure is crystal-grown at a temperature of 600 ° C. or higher and 750 ° C. or lower. A compound semiconductor containing P (phosphorus) as a V group element is stacked, and a compound semiconductor having only As as a V group element is stacked thereon, and at least 1 molecular layer and 10 molecular layers are stacked thereon. 4. The method for producing a compound semiconductor according to claim 1 , further comprising a step of crystal growth of a group III-V compound semiconductor crystal containing both As and As . 5. The method according to claim 1 , further comprising a step of supplying only an N raw material immediately before crystal growth of a group III-V compound semiconductor crystal containing both N and As as a group V element. A method for producing a compound semiconductor. A compound semiconductor device having a stacked structure including at least one group III-V compound semiconductor crystal containing both N (nitrogen) and As (arsenic) as group V elements on a semiconductor substrate,
The surface on which the semiconductor substrate is made of zinc blende type semiconductor crystal and the orientation of the surface on which the group III-V semiconductor is laminated is the Miller index (001) is inclined in the direction index <1-10> direction. Is inclined,
The group III-V compound semiconductor crystal containing both N and As as the group V element has a composition ratio of [N atom density] / ([N atom density] + [ As atom density]) is 0.025 or more,
A compound semiconductor device, wherein a zinc blende type semiconductor crystal used as the semiconductor substrate is made of GaAs.

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