JP2005159152A - Manufacturing method of iii-v compound semiconductor crystal and manufacturing method of semiconductor device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a III-V compound semiconductor crystal which is free from composition separation and subjected to carbon doping with good crystallinity small in hole-type defect density, and to provide a manufacturing method of a semiconductor device using the manufacturing method. <P>SOLUTION: When a III-V compound semiconductor crystal is formed on a substrate by supplying a group V raw material mainly containing a hydride or an organic compound of a group V element to the substrate, a growth temperature is held at 560 to 650C°, preferably higher than 585C° and lower than 650C°, and the ratio of a mole supply amount of the group V raw material to the mol supply amount of a group III raw material is set to be 25 to 100 when the hydride of the group V element is used, 10 to 50 when the organic compound of the group V element is used, a growth velocity is set to be 0.2 to 5 μm/h, and a dopant gas containing carbon is supplied to the substrate. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for producing a group III-V compound semiconductor crystal that is carbon-doped when a group III-V compound semiconductor crystal is grown on a substrate.

  InAlGaAs-based material formed on an InP substrate has characteristics such as high differential gain and large conduction band discontinuity compared to InGaAsP-based material. Known as. The reason why the InAlGaAs-based material can improve the laser characteristics is that the conductor band discontinuity ΔEc of the InGaAsP-based material is as small as ΔEc = 0.39ΔEg with respect to the overall band gap difference ΔEg, whereas in the InAlGaAs-based material, ΔEc = This is because 0.72ΔEg and the band discontinuity on the conduction band side are large, the electrons are confined efficiently, and the overflow of electrons accompanying a rise in temperature is small. Furthermore, since the InAlGaAs-based material has high electron mobility, it is a material system suitable for high speed even in electronic devices such as HBT and FET.

  When an InAlGaAs-based material is applied to a device, p-type doping is necessary as in other material systems. Usually, as described in Non-Patent Document 1, zinc is used as a dopant. However, zinc doping has a problem in that zinc moves during crystal growth because of its high diffusion coefficient. In the case of a semiconductor laser, when such a dopant diffuses to the active layer of the laser, it becomes a non-radiative recombination center and the laser characteristics are greatly deteriorated. In the case of an electronic device, the pn junction position is shifted and the peak concentration of p-type doping is reduced, resulting in deterioration of characteristics.

  Magnesium, beryllium and the like are known as p-type dopants having a small diffusion coefficient. However, since magnesium is highly reactive, it often adheres to the upstream side of the pipe or the like when it is introduced, which acts as a memory effect and gradually reaches the substrate and is taken in even after the introduction is stopped. For this reason, even if magnesium is used as the dopant, it is still impossible to precisely control the doping profile. Beryllium is rarely used in MOVPE because it is so toxic that it surpasses arsine.

  On the other hand, carbon has also been tried as an AlGaAs-based material or InAlAs-based material as a dopant having a low diffusion coefficient and low toxicity. Since carbon doping has a small diffusion coefficient as shown in Non-Patent Document 2, it is possible to realize a steep doping profile with good controllability. Furthermore, the oscillation of a semiconductor laser using carbon-doped InAlAs as a separate confinement layer has been reported (Non-patent Document 4).

  Carbon doping into the InAlAs-based material is described in Non-Patent Document 3, where the substrate temperature is 550 ° C., the ratio of the total molar supply amount of the Group V raw material to the total molar supply amount of the Group III raw material (hereinafter, The p-type doping is realized under the condition of 200 (referred to as V / III ratio). However, the InAlAs-based material has a weak bond between indium and carbon, so that it is difficult for carbon to be taken in. Therefore, when carbon doping is performed with the InAlAs-based material, there is a problem that the crystal needs to be grown at a low temperature (non-patent document). Reference 3).

On the other hand, in order to realize InAlAs having good crystal quality, it has been reported that a high temperature and a high V / III ratio are essential (see Non-Patent Document 5). According to the above-mentioned Non-Patent Document 3, although the increase in oxygen concentration that becomes a non-radiative recombination center is small even at a low temperature growth of 550 ° C., InAlAs grown at a low temperature and a low V / III ratio include There is concern about an increase in vacancy-type defect density and deterioration of crystallinity due to composition separation. In fact, according to Non-Patent Document 6, it is reported that composition separation occurs in InAlAs at low temperatures. Further, in the aforementioned non-patent document 4, laser oscillation is shown. However, when the crystallinity of InAlAs is affected, the characteristics can be further improved by improving the crystallinity.
From the above, in carbon-doped InAlAs, in order to obtain good crystallinity while ensuring the carrier concentration, it is necessary to study from various aspects. The window of growth conditions that satisfy these conditions is expected to be narrow, and no clear guidelines have been obtained.
IEEE Photonics Technology Letters vol.11 No.8 (1999) p949-951 Journal of crystal growth vol. 111 (1991) p274-279 Journal of crystal growth vol. 254 (2003) p6-14 IPRM2003 Proceeding WA2.6 Journal of Crystal Growth Vol. 108 (1991) p441-448 Materials Science & Engneering B64 (1999) p174-179

  The present invention has been made in consideration of the above-mentioned problems of the prior art, and an object of the present invention is to provide a simple carbon doping method in III-V group compounds including InAlGaAs. And In particular, an object of the present invention is to provide a method capable of producing a group III-V compound semiconductor crystal having good quality while accurately controlling a carbon doping profile.

  Furthermore, another object of the present invention is to provide a semiconductor device manufacturing method in which a III-V compound semiconductor layer is formed using the above-mentioned III-V compound semiconductor crystal manufacturing method.

  As a result of intensive studies to achieve the above object, the present inventors succeeded in performing carbon doping in a III-V group compound semiconductor crystal containing In and Al without impairing the crystal quality. That is, according to the present invention, it is possible to obtain a III-V group compound semiconductor crystal subjected to desired carbon doping under low oxygen conditions in a state where the vacancy-type defect density is small and composition separation is suppressed.

  An object of the present invention is to supply a group III material containing In and Al and a group V material mainly composed of a hydride of a group V element to a substrate, and form a group III-V compound semiconductor crystal on the substrate. A III-V group compound semiconductor, characterized in that the substrate temperature is maintained at 560-650 ° C., the V / III ratio is 25-100, and a dopant gas containing carbon is supplied to the substrate during the growth. This is achieved by a crystal production method.

  Another object of the present invention is to supply a group III material containing In and Al and a group V material mainly composed of an organic compound of a group V element to a substrate, and a group III-V compound semiconductor on the substrate. When growing a crystal, a substrate temperature is maintained at 560 to 650 ° C., a V / III ratio is set to 10 to 50, and a dopant gas containing carbon is supplied to the substrate. This can also be achieved by a method for producing a compound semiconductor crystal.

  In the method for producing a group III-V compound semiconductor crystal of the present invention, the growth temperature is preferably maintained at a temperature higher than 585 ° C. and not higher than 650 ° C.

  In the method for producing a group III-V compound semiconductor crystal of the present invention, when the group III-V compound semiconductor crystal is grown on the substrate, the group III material and the group V material are lattice-matched with the substrate. it can.

  In the method for producing a III-V compound semiconductor crystal of the present invention, the growth rate of the III-V compound semiconductor crystal is preferably 0.2 to 5 μm / hour in the growth process of the III-V compound semiconductor crystal. .

  In the method for producing a group III-V compound semiconductor crystal of the present invention, a group V material having at least As as a main group V element can be preferably used as the group V material.

  In the method for producing a III-V compound semiconductor crystal of the present invention, As and InAlGaAs or InAlAs composed of In, Al, In, Al, or Ga can be preferably used as the III-V compound semiconductor crystal.

  Moreover, in the manufacturing method of the III-V group compound semiconductor crystal of this invention, an organometallic compound can be preferably used as a III group raw material supplied to a board | substrate.

  In the method for producing a semiconductor device of the present invention, the III-V compound semiconductor layer can be formed using the method for producing a III-V compound semiconductor crystal.

  The method for producing a III-V compound semiconductor crystal of the present invention uses an organic compound when the substrate temperature is maintained at 560 to 650 ° C. and the V / III ratio is 25 to 100 when a hydride of a V group element is used. In some cases, a dopant gas containing carbon is supplied to the substrate in a state of 10 to 50. For this reason, according to the III-V compound semiconductor crystal manufacturing method of the present invention, an optimized carbon-doped InAlAs layer, InAlGaAs layer, or other III-V compound semiconductor layer can be formed. An accurate doping profile can be realized. Furthermore, according to the method for producing a group III-V compound semiconductor crystal of the present invention, since the crystallinity is not deteriorated, it can be used in the vicinity of the active layer or a part of the group III-V compound semiconductor layer constituting the active layer.

  According to the method for producing a group III-V compound semiconductor crystal of the present invention, the carrier traveling time can be shortened by bringing the doping front close to the active layer. Further, according to the method for producing a III-V group compound semiconductor crystal of the present invention, it is possible to control the Fermi level by selectively doping only the active layer barrier portion. Furthermore, according to the method for producing a group III-V compound semiconductor crystal of the present invention, by doping the heterointerface, electrical resistance can be reduced, and high-speed modulation characteristics can be realized while maintaining high light emission characteristics. In particular, according to the manufacturing method of the present invention, since a group III-V compound semiconductor layer having a low defect density in the crystal and maintaining good flatness of the interface can be provided, the semiconductor layer is arranged in the vicinity of the active layer. Even so, the characteristics are not deteriorated.

  Furthermore, the manufacturing method of the semiconductor device of this invention uses the manufacturing method of the III-V group compound semiconductor crystal of this invention in the process of forming a III-V group compound semiconductor layer. Thereby, according to the manufacturing method of the semiconductor device of this invention, the semiconductor device which has the high light emission characteristic which can respond to high-speed and high output can be provided.

Below, the manufacturing method of the III-V compound semiconductor crystal of this invention and the manufacturing method of the device using this manufacturing method are demonstrated in detail.
In the present specification, a numerical range represented by using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.

[Method for Producing III-V Compound Semiconductor Crystal]
The method for producing a group III-V compound semiconductor crystal of the present invention supplies a group III material containing In and Al and a group V material mainly composed of a hydride of a group V element to the substrate. A III-V compound semiconductor crystal is grown.
The group III raw material used in the production method of the present invention is not particularly limited as long as it is a material system containing at least In and Al as group III elements. For example, organometallic compounds such as trimethylindium (TMIn), trimethylaluminum (TMAl), trimethylgallium (TMGa), and triethylgallium (TEGa) can be used as the group III material. In particular, it is preferable to use a group III raw material having a Al / Ga ratio of 1: 1 or more and a high Al content.

The group V raw material used in the production method of the present invention is not particularly limited as long as it is a group V raw material mainly containing a hydride of a group V element or an organic compound. The group V raw material, for example, arsine (AsH3), phosphine (PH ₃₎ other hydrides, such as, tertiary butyl arsine (TBAs), trimethyl arsine (TMAs), tributylphosphine (TBP), tris dimethylamino arsine ( Organic compounds such as TDMAAs) and trisdimethylaminophosphine (TDMAP) can be used. Among them, As such as arsine (As), tertiary butylarsine (TBAs), and trimethylarsine (TMAs) is the main group V element. It is preferable to use raw materials.

The dopant gas containing carbon used in the production method of the present invention is not particularly limited, and examples thereof include carbon tetrabromide (CBr ₄ ), carbon tetrachloride (CCl ₄ ), and trimethylarsine (TMAs). Carbon tetrabromide (CBr ₄ ) is preferably used in consideration of the environment and ease of control.

The addition amount of the dopant gas containing carbon is not particularly limited, but the carbon doping concentration can be changed by controlling the addition amount of the gas. For example, in the case of carbon tetrabromide, a concentration of 1 × 10 ¹⁸ cm ⁻³ can be obtained at ³ μmol / min. When carbon tetrabromide is used, carbon tetrabromide is a dopant with little saturation, so the range of addition is wide, but considering the doping range, the lower limit is about 0.3 μmol / min, and the upper limit is 300 μmol / min. Is preferable, and it is more preferable that it is 1-100 micromol / min.

  In the production method of the present invention, when a group III-V compound semiconductor crystal is grown on a substrate, the growth temperature, that is, the temperature of the substrate is maintained at 560 to 650 ° C., and a hydride of a group V element is used as a group V raw material. In this case, the V / III ratio is set to 25 to 100, and in the case of an organic compound of a group V element, the V / III ratio is set to 10 to 50. The manufacturing method of the present invention supplies a dopant gas containing carbon to the substrate at the growth temperature and the V / III ratio.

  According to a conventional report (Non-Patent Document 3), the growth condition of the carbon-doped InAlAs compound semiconductor crystal was a growth temperature of 500 ° C. and a V / III ratio of around 200. However, subsequent investigations by the present inventors have revealed that compositional separation is unavoidable under the above growth conditions, and the vacancy-type defect density is also large. Therefore, as a result of intensive studies on the growth conditions, the present inventors have determined that the oxygen concentration can be adjusted by adjusting the V / III ratio and the growth rate necessary for securing the carbon concentration at a growth temperature higher than 560 ° C. It has been found that the compositional separation and the suppression of the vacancy-type defect density can be achieved at the same time, and the device characteristics can be improved.

  FIG. 1 shows a transmission electron microscope (TEM) photograph of the InAlAs layer when the growth temperature of the InAlAs compound semiconductor crystal is changed. When the growth temperature is 618 ° C. (FIG. 1A), it can be seen that the InAlAs compound semiconductor crystal is lattice-matched with the substrate, and is uniform and has a flat interface. The lattice matching is obtained by X-ray diffraction measurement or the like, and it is appropriate that the lattice mismatch rate is 1% or less, preferably 0.7% or less, more preferably 0.5% or less. When the growth temperature is 580 ° C. (FIG. 1B), the morphology changes slightly at about 0.15 μm from the growth start interface, and a slight compositional separation occurs, but a thin layer of 0.15 μm or less. When the growth temperature is 550 ° C. (FIG. 1C), the vertical stripes corresponding to the composition separation are observed. It can be seen that the contrast is increased and the height difference of the unevenness at the interface between the InAlAs surface and the InP surface is increased.

  FIG. 2 shows the relationship between the oxygen concentration and carbon concentration (vertical axis) and the growth rate (horizontal axis) in the manufacturing process of the carbon-doped InAlAs compound semiconductor crystal when the growth rate is changed. Here, the growth rate was adjusted by changing the group III supply amount while keeping the arsine supply amount constant. As shown in FIG. 2, the slower the growth rate, the lower the carbon concentration and the higher the oxygen concentration. This is presumed that the element captured at the group V site is easily incorporated in the order of oxygen, arsenic, and carbon, and that the difference (competition) in the incorporation is more emphasized when the growth rate is slow. The Therefore, it can be seen that it is desirable that the growth rate is somewhat high. 1 shows that the surface of this material system is likely to be three-dimensional. However, in the case of a material system containing In, it has been reported that a higher growth rate is less likely to be three-dimensional (Journal of vacuum science and technology B19 (4) (2001) p1550).

Next, in order to investigate the degree of vacancy-type defect density, the results of positron pair annihilation experiments of carbon-doped InAlAs compound semiconductor crystals produced at 580 ° C. and 618 ° C. are shown in FIG. The carrier concentration varies depending on the carbon concentration and the oxygen concentration to compensate for it, but the carbon carrier supply amount is adjusted to the same carrier concentration of 1 × 10 ¹⁸ cm ⁻³ . Further, in carbon-doped InAlAs having growth temperatures of 580 ° C. and 618 ° C., 75 and 40 were adopted as V / III ratios for achieving a low oxygen concentration, respectively.

  Positron pair annihilation experiment is a technique to measure the defect density by taking advantage of the fact that negatively charged vacancy-type defects easily capture positrons, and the defect density is reflected in the positron lifetime (annihilation rate). Is done. The annihilation rate of positrons is called the S parameter, and it is used as an index for measuring the amount of introduced vacancy defects using the S parameter. It is known that the larger the S parameter, the shorter the positron lifetime and the higher the vacancy-type defect density (Applied Physics Letters vol. 78 Mo. 1 (2001) p28: hereinafter referred to as “Document A”).

As shown in FIG. 3, when the growth temperature of InAlAs is 580 ° C., the S parameter is as large as 0.53, and when the growth temperature is 618 ° C. or higher, the S parameter is as small as 0.52. Although not shown in FIG. 3, when the growth temperature is 550 ° C. or lower, the S parameter is further increased, and the vacancy-type defect density (point defect density) is further increased. Here, the difference in the S parameter between the growth temperatures is the second decimal place (10 ^-2 ). At first glance, it seems that there is not much difference. Comparative evaluation is possible (see the above-mentioned document A). This is because if the numerical value of the S parameter is reduced by about 0.01, the vacancy-type defect density is lower and it means that crystals of better quality are formed. Such a vacancy-type defect density becomes a non-radiative recombination center, which causes deterioration of device characteristics.
From the above facts, it was found that composition separation occurred in low-temperature growth lower than 560 ° C., and as a result, the unevenness of the interface was large and the vacancy-type defect density increased.

  From the above positron pair annihilation experiment and S parameter experiment, it was found for the first time that the critical temperature at which composition separation occurs in the InAlAs compound semiconductor crystal is 560 ° C. It has also been found that when a crystal is grown at a low growth rate, a disadvantageous phenomenon occurs from the viewpoint of carbon doping in which the oxygen concentration increases and the carbon concentration decreases. Furthermore, a significant difference is observed in the vacancy-type defect density at a growth temperature of 560 to 650 ° C. For example, when the growth temperature is 618 ° C., it is possible to achieve a favorable point defect density lower than that of conventional zinc doping. understood.

  On the other hand, since the element migration length during crystal growth becomes shorter at low temperatures, defects are likely to be generated, and when there is a composition separation, strains are concentrated locally, so defects are expected to increase. For this reason, it is reasonable that the critical temperature at which compositional separation occurs coincides with the temperature at which the defect density starts to increase. Further, although the results of the positron experiment when the growth temperature is a low temperature of 550 ° C. are not shown, it has been found that the defect density is further increased.

  From the above knowledge, it is necessary for InAlAs-based compound semiconductor crystals to obtain good device characteristics by performing composition separation and suppression of vacancy-type defect density at a growth temperature of at least 560 ° C. or higher. Was found for the first time. Some compositional separation occurs at around 560 ° C., but this is at least when the layer thickness of the InAlAs compound semiconductor crystal is thicker than 0.15 μm, and it is considered that compositional separation does not occur when it is thinner than that. Therefore, the growth temperature of the InAlAs compound semiconductor crystal is suitably 560 ° C. or higher, preferably 570 ° C., more preferably 580 ° C., and even more preferably 585 ° C. When the growth temperature is further increased, there is no concern that composition separation will occur even if the film thickness is increased. In view of the fact that the vacancy-type defect density is reduced at 618 ° C., the growth temperature is more preferably 600 ° C. or higher, and further preferably 610 ° C. or higher. On the other hand, since the carbon uptake is inhibited at a high temperature, the upper limit of the growth temperature is suitably at least 650 ° C. From the viewpoint of increasing the carbon concentration, the growth temperature is 630 ° C. or lower. More preferably it is.

  The V / III ratio in the above temperature range is suitably 100 or less from the viewpoint of increasing the carbon concentration when a hydride containing a group V element (preferably As) is used for the group V gas. Since the carbon concentration decreases as the growth temperature increases, the V / III ratio is preferably 80 or less from the viewpoint of securing the carbon concentration. The lower limit of the V / III ratio is defined from the viewpoint of suppressing the increase in oxygen concentration. However, since the decomposition efficiency of arsine is improved at higher temperatures, the necessary minimum amount is preferably 25 or more, and the oxygen concentration is further reduced. From the viewpoint of reduction, it is more preferably 30 or more.

  The V / III ratio is compared with the case where an organic compound containing As such as tertiary butylarsine (TBA) or trimethylarsenic (TMAs) is used as the group V gas, compared with the case where the group V raw material of the hydride is used. And since decomposition efficiency is high, it is preferable that it is 10-50, it is more preferable that it is 10-40, and it is further more preferable that it is 10-30.

  It is considered appropriate that the growth rate is at least 0.2 μm / h or more from the viewpoint of lowering the oxygen concentration and raising the carbon concentration. On the other hand, the upper limit of the growth rate is often determined by the requirements of the apparatus regarding indium, but is suitably 5 μm / h. The lower limit of the growth rate is preferably 0.2 to 3 μm / h, more preferably 0.5 to 3 μm / h, from the viewpoint of easy control of oxygen uptake.

  In the above description, an example of an InAlAs-based compound semiconductor crystal has been given. In the present invention, a III-V group compound semiconductor crystal includes other elements such as Ga, P, and N in addition to In, Al, and As. , Sb and the like may be contained. When the composition of the group V element is different, the ratio of the bond energy of In, Al, and C is the same, so any kind of group V element can be used, but all group V elements other than As are all group V elements. It is desirable to make it 50% or less in the element.

  In the production method of the present invention, the method for growing the III-V compound semiconductor crystal on the substrate is not particularly limited, and various growth methods can be used. For example, as a method using an organometallic compound, a chemical beam epitaxy method (CBE), a organometallic molecular beam epitaxy method (MOMBE), and the like can be given. It is most desirable to use a metal organic vapor phase epitaxy method (MOVPE).

[Method of Manufacturing Semiconductor Device of the Present Invention]
The method for producing a semiconductor device of the present invention uses the aforementioned method for producing a group III-V compound semiconductor crystal of the present invention in the step of forming a group III-V compound semiconductor layer. If the manufacturing method of the semiconductor device of this invention uses the manufacturing method of the III-V group compound semiconductor crystal of this invention in the process of forming a III-V compound semiconductor layer, the raw material in other processes, manufacture The conditions, equipment, and materials used in general semiconductor device manufacturing methods, conditions, and equipment can be applied as they are.

  The features of the present invention will be described more specifically with reference to the following examples. The materials, amounts used, ratios, processing details, processing procedures, and the like shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the specific examples shown below.

Example 1
In this example, a device having the structure shown in FIGS. 4 and 5 was manufactured. In the drawings attached to the present specification, there are portions where the dimensions are intentionally changed in order to make the structure easy to grasp, but the actual dimensions are as described in the following text.

As shown in FIG. 4, the following semiconductor laser substrate 1 was fabricated on an n-type InP substrate 10 by using the MOVPE method.
N-type InP layer 11 having a thickness of 500 nm, n-type In _0.52 Al _0.48 As layer 12 having a thickness of 100 nm, In _0.52 (Al _x Ga _1-x ) _0.48 As having a thickness of 80 nm (0.74 <x <1) Rate (GRIN) layer 13, five-period multiple quantum well layer 14 (InAlGaAs) having a compression strain of 1.5% and a band gap wavelength of 1.3 μm, and a barrier layer 15 having a thickness of 10 nm and a band gap wavelength of 1.0 μm (InAlGaAs) Active layer 16 having a thickness of 80 nm, In _0.52 (Al _x Ga _1-x ) _0.48 As (0.74 <x <1) upper gradient refractive index (GRIN) layer 17, 100 nm thick carbon-doped In _0.52 Al _0.48 As-SCH layer 18, p-type InP spacer layer 19 having a thickness of 50 nm, a thickness of 10 nm, InGaAsP etch stop layer 20 of bandgap wavelength 1.1 .mu.m, a thickness of 1.5 [mu] m p-type InP Utakuraddo layer 21 was laminated a p-type In _0.53 Ga _0.47 As contact layer 22 having a thickness of 200nm in this order.

When producing the carbon doped layer, a mixed gas of TMIn, TMAl, TMGa, AsH ₃ , H ₂ , and CBr ₄ was used as a raw material. The growth temperature was 618 ° C. and 580 ° C. The growth rate was all 1 μm / h, and the carrier concentration was carbon-doped into the p-type InAlAs-SCH layer 18 close to the active layer so that the carrier concentration was 1 × 10 ¹⁸ cm ⁻³ by adjusting the dopant supply amount.

After the carbon-doped InAlGaAs semiconductor laser substrate 1 is formed as described above, an InAlGaAs semiconductor laser element A (growth temperature 618 ° C.) and an element B (growth temperature) as shown in FIG. 580 ° C.). First, a striped photoresist mask having a width of about 12 μm and a pitch of about 300 μm was formed on the laminated structure, and wet etching was performed using the photoresist mask as a mask to form the ridge 25. During the wet etching, a mixed aqueous solution of phosphoric acid and hydrogen peroxide was used for the p-type InGaAs contact layer 22, and a diluted aqueous solution of hydrochloric acid was used for the p-type InP outer cladding layer 21. As a result, the etching can be stopped at the InGaAsP etch stop layer 20 and the controllability is improved. Thereafter, the photoresist was peeled off to form a Si ₃ N ₄ dielectric film 26 as an insulating film on the entire surface. Further, a contact hole 27 was selectively opened on the stripe on the mesa upper surface portion of the Si ₃ N ₄ dielectric film 26 to form a p-type electrode 28. The substrate side was polished to a thickness of about 100 μm to form an n-type electrode 29. After such a process, a laser chip having a cavity length of about 1000 μm was cut out, and a dielectric multilayer film having a reflectivity of 94% was formed on the facet surface opposite to the end face from which light output was obtained, thereby completing a semiconductor laser. .

Comparative Example 1
A device C was produced by the same method and conditions as in Example 1 except that the growth rate was 550 ° C.

FIG. 6 shows current-light output characteristics by pulse driving of the elements A to C manufactured as described above. Regarding the oscillation threshold density, the difference between the elements was small and was about 1.6 kA / cm ² , but the maximum light output was greatly different between the elements. That is, as shown in FIG. 6, the devices A and B have a maximum light output of 150 mW or more, and the device A has good characteristics. On the other hand, the element C was thermally saturated at only about 36 mW, and a higher light output could not be obtained. This result is considered to reflect the crystal characteristics of InAlAs, and is considered to be consistent with the presence or absence of compositional separation and the change in vacancy-type defect density.

  In this embodiment, InAlAs on an InP substrate is used. However, the present invention is also effective for a compound semiconductor containing elements other than In, Al, and As. For example, Ga can be included as Group III, and N or P can be included as Group V, but it is desirable that the Group V elements other than As be 50% or less of all the Group V elements.

  The method for producing a group III-V compound semiconductor crystal of the present invention can be used as a method for producing a group III-V compound semiconductor crystal having good quality while accurately controlling the carbon doping profile. In addition, the method for manufacturing a semiconductor device of the present invention can be used as a method for manufacturing a semiconductor device having high light emission characteristics that can cope with high speed and high output.

  The carbon-doped InAlGaAs compound semiconductor crystal produced by the production method of the present invention contributes to improvement of device characteristics when used as a semiconductor laser layer structure, but the layer formed of the carbon-doped InAlAs compound semiconductor crystal has a band structure. Therefore, it is expected to be used as an electronic device such as a heterobipolar transistor. Examples of the electronic device having a layer formed of the compound semiconductor crystal include a hetero bipolar transistor (HBT), a field effect transistor (FET), and a high electron mobility transistor (HEMT). In this case as well, carbon doping with a small diffusion coefficient can not only precisely control the doping profile by suppressing composition separation, but also allows doping with high hole mobility reflecting good crystallinity. Therefore, it contributes to the improvement of device characteristics.

It is a transmission electron microscope (TEM) photograph of the layer formed with the InAlAs compound semiconductor crystal in case growth temperature is 618 degreeC (A), 580 degreeC (B), and 550 degreeC (C). It is explanatory drawing which shows the carbon concentration and residual oxygen concentration in a carbon dope InAlAs layer when changing a growth rate. It is explanatory drawing which shows the depth dependence of the S parameter obtained by the positron pair annihilation experiment about the layer formed with the InAlAs compound semiconductor crystal in case growth temperature is 580 degreeC and 618 degreeC. It is a figure which shows the profile of the refractive index of an InAlGaAs type | system | group semiconductor laser structure. 1 is a schematic cross-sectional view of an InAlGaAs-based semiconductor laser structure. It is a figure which shows the electric current-light output characteristic of the InAlGaAs type | system | group semiconductor laser in the case of changing the growth temperature of an InAlAs compound semiconductor layer.

Explanation of symbols

1 Carbon-doped InAlGaAs semiconductor laser substrate 10 n-type InP substrate 11 n-type InP layer 12 n-type In _0.52 Al _0.48 As layer 13 In _0.52 (Al _x Ga _1-x ) _0.48 As (0.74 <x <1) Index (GRIN) layer 14 5-period multiple quantum well layer 15 barrier layer 16 active layer 17 In _0.52 (Al _x Ga _{1 -x} ) _0.48 As (0.74 <x <1) upper graded refractive index (GRIN) layer 18 p-type In _0.52 Al _0.48 As-SCH layer 19 p-type InP spacer layer 20 InGaAsP etching stop layer 21 p-type InP outer cladding layer 22 p-type In _0.53 Ga _0.47 As contact layer 25 ridge 26 Si ₃ N ₄ dielectric film 27 contact hole 28 p-type electrode 29 n-type electrode

Claims (9)

When a group III source material containing In and Al and a group V source mainly composed of a hydride of a group V element are supplied to a substrate, and a group III-V compound semiconductor crystal is grown on the substrate, it grows. The temperature is maintained at 560 to 650 ° C., the ratio of the molar supply amount of the group V raw material to the molar supply amount of the group III raw material is 25 to 100, and a dopant gas containing carbon is supplied to the substrate. A method for producing a III-V compound semiconductor crystal. When a group III material containing In and Al and a group V material mainly composed of an organic compound of a group V element are supplied to a substrate, and a group III-V compound semiconductor crystal is grown on the substrate, the growth is performed. The temperature is maintained at 560 to 650 ° C., the ratio of the molar supply amount of the group V raw material to the molar supply amount of the group III raw material is 10 to 50, and a dopant gas containing carbon is supplied to the substrate. A method for producing a III-V compound semiconductor crystal. The method for producing a III-V group compound semiconductor crystal according to claim 1 or 2, wherein the growth temperature is maintained at a temperature higher than 585 ° C and not higher than 650 ° C. The group III-V according to any one of claims 1 to 3, wherein when the group III-V compound semiconductor crystal is grown on the substrate, the group III material and the group V material are lattice-matched with the substrate. A method for producing a compound semiconductor crystal. The growth rate of the said III-V group compound semiconductor crystal is 0.2-5 micrometers / h, The manufacturing method of the III-V group compound semiconductor crystal as described in any one of Claims 1-4. The method for producing a III-V compound semiconductor crystal according to any one of claims 1 to 5, wherein a raw material containing at least As as a main group V element is used as the group V raw material. The method for producing a group III-V compound semiconductor crystal according to any one of claims 1 to 6, wherein the group III-V compound semiconductor crystal is an InAlGaAs compound semiconductor crystal or an InAlAs compound semiconductor crystal. The method for producing a group III-V compound semiconductor crystal according to any one of claims 1 to 7, wherein an organometallic compound is used as the group III raw material. A method for manufacturing a semiconductor device, comprising forming a group III-V compound semiconductor layer using the method for manufacturing a group III-V compound semiconductor crystal according to claim 1.