JP5215267B2 - Method for producing compound semiconductor film - Google Patents

Description

The present invention relates to a compound semiconductor manufacturing how high the compound semiconductor film having a carrier concentration that is doped with an impurity at a high concentration in the crystal.

In a semiconductor device that operates by current injection, a semiconductor film to which an impurity is added (referred to as doping) at a high concentration (generally 10 ¹⁹ cm ⁻³ or more) is required in order to realize ohmic contact with an electrode. . In particular, in order to operate the device at high speed, it is desirable that the contact resistance generated between the metal serving as the electrode and the semiconductor film is low, and it is necessary to increase the impurity concentration as much as possible to increase the carrier concentration.

Conventionally, for example, in a semiconductor laser manufactured using an InP substrate, a ternary mixed crystal InGaAs lattice-matched to InP or a p-type semiconductor film in which quaternary mixed crystal InGaAsP is doped with zinc is used as a contact layer. The doping concentration is about 1 × 10 ¹⁹ cm ⁻³ . In general, in order to lower the contact resistance between the contact layer and the electrode, after depositing an alloy electrode containing zinc, the metal and the semiconductor film are alloyed by heat treatment at about 400 ° C.

  However, it is difficult to control the diffusion of zinc into the semiconductor due to alloying, and in some cases, it diffuses not only into the contact layer but also into the cladding layer and the active layer. The diffusion of zinc into the cladding layer and active layer greatly degrades the laser characteristics. In order to avoid this, a non-alloy electrode capable of realizing ohmic contact without increasing the carrier concentration of the contact layer and forming an alloy is used.

D. C. Chapman et al., "Zn enhancement during surfactant-mediated growth of GaInP and GaP", Journal of Crystal Growth, Vol. 287, 2006, pp. 647-651 AD Howard et al., "Effect of surfactants Sb and Bi on the incorporation of zinc and carbon in III / V materials grown by organometallic vapor-phase epitaxy", Journal of Applied Physics, Vol. 100, 044904, 2006, pp. 1 -8 A. D. Howard et al., "Effect of low surfactant Sb coverage on Zn and C incorporation in GaP", Journal of Applied Physics, Vol. 102, 074920, 2007, pp. 1-5

For example, in a semiconductor laser manufactured using an InP substrate described in the prior art, it is desired that the p-type semiconductor contact layer used for forming the non-alloy electrode has a high carrier concentration. However, it is difficult to dope zinc, which is widely used as a p-type dopant, at a high concentration from the viewpoint of the solid solution limit of the semiconductor material, and is about 2 × 10 ¹⁹ cm ⁻³ at most. With this carrier concentration, it is difficult to sufficiently reduce the contact resistance in the non-alloy electrode, leading to deterioration of element characteristics of the semiconductor device. In order to solve this, techniques such as growing the zinc-doped semiconductor film at a low temperature to increase the carrier concentration are used, but problems remain in the reproducibility of the manufacturing accuracy and the yield. Furthermore, improvement in controllability of the zinc doping concentration is also desired.

This invention is made | formed in view of the said subject, and it aims at providing the manufacturing method of the compound semiconductor film which can increase the uptake | capture amount of zinc in a compound semiconductor crystal .

A method for producing a compound semiconductor film according to the first invention for solving the above-described problems is as follows.
Compound for producing a III-V compound semiconductor film using zinc as a p-type dopant, containing at least one of In, Ga, Al as a group III atom and at least one As, P as a group V atom other than N A method for manufacturing a semiconductor film, comprising:
Supplying trisdimethylaminoantimony or trimethylantimony which is a Sb-containing raw material containing Sb together with a zinc-containing raw material containing zinc;
The growth temperature of the compound semiconductor film is 400 ° C. or more and 540 ° C. or less,
The atomic percentage in the group V atoms of Sb taken into the compound semiconductor film is 0 at. %, 0.5 at. The zinc concentration and the carrier concentration contained in the compound semiconductor film are controlled to be 2 × 10 ¹⁹ cm ⁻³ or more by controlling in the range of % or less.
The atomic percentage in the group V atoms of Sb taken into the compound semiconductor film is 0 at. %, 0.5 at. By setting it in the range of% or less, the zinc concentration can be increased while maintaining the composition controllability of the compound semiconductor film.

  According to the present invention, during the epitaxial growth of the p-type compound semiconductor film doped with zinc, the Sb-containing raw material in a predetermined range is supplied together with the zinc-containing raw material, so that the composition controllability can be maintained while maintaining the composition controllability. The amount of zinc taken up can be increased, and a compound semiconductor film doped with impurities at a high concentration, which has been difficult to produce conventionally, can be easily produced. As a result, a p-type compound semiconductor film having a higher carrier concentration than the conventional one can be realized, and a contact layer having a low contact resistance with the non-alloy electrode can be obtained. A contact layer using the compound semiconductor film is extremely useful for improving the performance of semiconductor devices such as semiconductor lasers and light receiving elements.

1 is a cross-sectional view of a layer structure including a compound semiconductor film, shown as Example 1. FIG. It is a graph which shows an example of the relationship between the carrier density | concentration in the InGaAs layer grown at the growth temperature of 620 degreeC, and DEZn supply amount. It is a graph which shows an example of the relationship between the carrier concentration in the InGaAs layer grown at the growth temperature of 620 degreeC, the zinc concentration, and the TDMASb supply amount. It is a graph which shows an example of the relationship between the carrier density | concentration in an InGaAs layer, and DEZn supply amount about the InGaAs layer which did not supply TDMASb, and the InGaAs layer which was not performed. It is a graph which shows an example of the relationship between the carrier concentration in an InGaAs layer, and DEZn supply amount about the InGaAs layer grown at the growth temperature of 540 degreeC, and the InGaAs layer grown at 620 degreeC. It is a graph which shows an example of the relationship between the carrier concentration in the InGaAs layer grown at the growth temperature of 540 degreeC, the zinc concentration and the hydrogen concentration, and the TDMASb supply amount. It is a graph which shows an example of the relationship between Sb density | concentration in the InGaAs layer grown at the growth temperature of 540 degreeC, and the TDMASb supply amount. It is a graph which shows an example of the relationship between the carrier concentration and the DEZn supply amount in the InGaAs layer grown at the growth temperature of 540 ° C. and the TDMASb supply amount of 18.1 μmol / min. 6 is a schematic perspective view of a structure of a ridge structure distributed feedback laser shown as Example 4. FIG. 10 is a schematic perspective view of the structure of a waveguide type light receiving element shown as Example 5. FIG.

  A preferred embodiment of the present invention is described below.

Example 1
FIG. 1 is a cross-sectional view showing a layer structure including the compound semiconductor film of this example. The present embodiment will be described with reference to FIG.
As shown in FIG. 1, the compound semiconductor film (an InGaAs layer 12 described later) of this example is configured as a layer structure including the film. Specifically, after growing an InP buffer layer 11 (thickness: 200 nm) on the (100) plane of the InP substrate 10, InGaAs was substantially lattice matched to InP (lattice mismatch rate within ± 0.1%). The layer 12 and the InP cap layer 13 (film thickness 100 nm) are grown.

Crystal growth of each of the above layers was performed by a metal organic vapor phase epitaxy (MOVPE) method in which the reactor was decompressed to 50 Torr. The growth temperature is a value measured by placing a Si wafer embedded with a thermocouple on the susceptor of the MOVPE growth furnace. In this example, the growth temperature was set to 620 ° C. in all samples described later. In addition, trimethylindium (TMIn) and triethylgallium (TEGa) were used as Group III materials, and arsine (AsH ₃ ) and phosphine (PH ₃ ) were used as Group V materials.

  In particular, in the case of the InGaAs layer 12, diethyl zinc (DEZn) was used as a zinc-containing raw material that becomes a p-type impurity (p-type dopant). Trisdimethylaminoantimony (TDMASb) was used as the Sb-containing raw material. The DEZn supply rate was varied between 6.5 and 125.9 μmol / min, and the TDMASb supply rate was varied between 0 and 192.6 μmol / min. The growth rate of the InGaAs layer 12 is approximately 2.5 μm / hour, and the V / III ratio, which is the ratio of the supply amount of the group V material to the group III material, is 15.

  An X-ray diffractometer manufactured by Philips was used to evaluate the structural characteristics of the prepared sample. A CV profiler (PN-4200) manufactured by Biorad is used to measure the carrier concentration of the InGaAs layer 12, and a secondary ion mass spectrometer (SIMS) manufactured by CAMECA is used to measure the atomic concentration in the compound semiconductor film. Was used.

First, FIG. 2 shows the DEZn supply dependency of the carrier concentration of the zinc-doped InGaAs layer 12 manufactured under the above-described conditions. At this time, the supply amount of TDMASb is 0 μmol / min. As shown in FIG. 2, even if TDMASb is not supplied, the carrier concentration increases by increasing the DEZn supply amount. However, when the carrier concentration exceeds 1 × 10 ¹⁹ cm ⁻³ , the concentration is saturated. The tendency to do appears. Since the zinc concentration in the InGaAs layer under general growth conditions is saturated at about 2 × 10 ¹⁹ cm ⁻³ , the same tendency appears in this experiment.

  Next, the DEZn supply rate is fixed at 6.5 μmol / min, the TDMASb supply rate is changed between 0 to 192.6 μmol / min, and the InGaAs layer 12 is manufactured. FIG. 3 shows the dependency of carrier concentration and zinc concentration on TDMASb supply amount. The carrier concentration, zinc concentration, and zinc activation rate (ratio of carrier concentration to zinc concentration) in InGaAs layer 12 at each TDMASb supply amount are shown in FIG. Table 1 shows.

As shown in Table 1, as the TDMASb supply amount is increased, the carrier concentration is increased from 1.32 × 10 ¹⁸ cm ⁻³ to about 2.5 times × 2.58 × 10 ¹⁸ cm ⁻³ . As the supply amount of TDMASb increases, the zinc concentration increases in the same way as the carrier concentration. Therefore, the supply efficiency of zinc into the InGaAs layer 12 is increased by the supply of TDMASb, and as a result, the carrier concentration increases. Is clear. The activation rate of zinc at this time is constant at about 90% regardless of the supply amount of TDMASb. Further, since the carrier concentration depends on the TDMASb supply amount, the zinc concentration and the carrier concentration can be controlled only by changing the TDMASb supply amount without changing the DEZn supply amount. it can.

  Next, the carrier concentration in the InGaAs layer 12 when the TDMASb supply amount is fixed and the DEZn supply amount is changed will be described. In FIG. 3 described above, the TDMASb supply amount dependency was examined by keeping the DEZn supply amount constant at 6.5 μmol / min. On the other hand, in FIG. 4, the TDMASb supply amount is fixed and the DEZn supply amount is increased, and in this case as well, an effect of increasing the carrier concentration can be obtained as shown by ● (black circle) in FIG. Was confirmed. The black circles in FIG. 4 plot the carrier concentration when the TDMASb supply rate is fixed at 192.6 μmol / min and the DEZn supply rate is changed to 6.5, 72.1, 107.2 μmol / min. . Also, the circles (white circles) shown in FIG. 4 indicate the case where no TDMASb is supplied for comparison, and corresponds to the graph of FIG. It can be seen that at any DEZn supply amount, the carrier concentration is approximately doubled by supplying TDMASb as compared to the case where TDMASb is not supplied.

Table 2 shows the carrier concentration in the InGaAs layer 12 when TDMASb is not supplied and when it is supplied at each DEZn supply amount. Under normal conditions in which no TDMASb was supplied, the carrier concentration was saturated before reaching 2 × 10 ¹⁹ cm ⁻³ even when the supply amount of DEZn was increased. On the other hand, a carrier concentration of 2.6 × 10 ¹⁹ cm ⁻³ could be obtained under the conditions for supplying TDMASb.

From the above results, it was confirmed that the carrier concentration can be increased by supplying TDMASb during the growth of the zinc-doped InGaAs layer 12 as compared with the case where TDMASb is not supplied. Under the growth conditions used in this example, the carrier concentration can be increased up to about twice as much as that in the case where TMDASb is not supplied by controlling the supply amount of TDMASb. The maximum is 2.63 × 10 ¹⁹ cm ^−3. It has been confirmed that a carrier concentration of 1 can be obtained.

  In this example, DEZn and TDMASb were used as the zinc-containing material and the Sb-containing material. However, both materials are completely decomposed into zinc and Sb on the growth surface. In other words, any raw material that can supply zinc and Sb to the growth surface may be a combination of raw materials other than DEZn and TDMASb. For example, dimethylzinc (DMZn), which is an organometallic zinc-containing raw material, and trimethylantimony (Sb-containing raw material) The same effect can be obtained with any combination of TMSb) and the like.

  In this embodiment, the MOVPE method is used for the epitaxial growth of the compound semiconductor film. However, the growth method is not limited to the MOVPE method as long as it can supply zinc and antimony. For example, the same effect can be obtained by using molecular beam epitaxy or chemical beam epitaxy.

  In this embodiment, an InGaAs layer is used. However, since the present invention uses an effect of increasing zinc uptake by antimony, it can be applied to a compound semiconductor containing In, Ga, Al, As, P, or the like. For example, the same effect can be obtained also in the doping of zinc into the InAlAs layer, InAlGaAs layer, InGaAsP layer, and InAlGaAsP layer on the InP substrate.

(Example 2)
This example is different from Example 1 only in the growth temperature, and other growth conditions are the same as those in Example 1. Specifically, the growth temperature was lowered by 80 ° C. from the conditions in Example 1, and the layer structure including the InGaAs layer 12 shown in FIG.

In FIG. 5, ● represents the dependence of the carrier concentration in the zinc-doped InGaAs layer 12 grown at 540 ° C. on the DEZn supply amount. In addition, ◯ shown in FIG. 5 shows a case where the growth is performed at 620 ° C. for comparison, and corresponds to the graph of FIG. Lowering the growth temperature increases the efficiency of zinc incorporation into the InGaAs layer 12. When the carrier concentration is 1 × 10 ¹⁹ cm ⁻³ or less, the carrier concentration is about five times higher than that at 620 ° C. indicated by ◯ by lowering the growth temperature to 540 ° C. even with the same DEZn supply amount. However, when the carrier concentration is 1 × 10 ¹⁹ cm ⁻³ or more, the carrier concentration is saturated at 2.7 × 10 ¹⁹ cm ⁻³ even if the DEZn supply amount is increased. From this, the zinc uptake efficiency is increased by lowering the growth temperature, and the maximum carrier concentration obtained is increased about twice as compared with the case where the growth temperature is not lowered (O).

  Next, the DEZn supply rate is fixed at 6.5 μmol / min, the TDMASb supply rate is changed between 0 to 192.6 μmol / min, and the InGaAs layer 12 is manufactured. FIG. 6 shows the dependency of carrier concentration, zinc concentration, and hydrogen concentration on TDMASb supply amount. Table 3 shows the carrier concentration, zinc concentration, and zinc activation rate (ratio of the carrier concentration to the zinc concentration) in the InGaAs layer 12 at each TDMASb supply amount.

As shown in FIG. 6 and Table 3, although the DEZn supply amount is constant, when the TDMASb supply amount is increased, the carrier concentration increases rapidly, and when the TDMASb supply amount is 30.6 μmol / min, FIG. A value of 2.95 × 10 ¹⁹ cm ⁻³ higher than the saturated carrier concentration shown in FIG. When the TDMASb supply amount was further increased, the carrier concentration was saturated, but a maximum carrier concentration of 4.34 × 10 ¹⁹ cm ⁻³ was obtained. Compared to the case where TDMASb is not supplied, the carrier concentration is five times as high. In all samples, the activation rate of zinc was as high as about 90%.

  Next, the composition variation of the InGaAs layer 12 when the TDMASb supply amount is increased will be described. The growth conditions of the InGaAs layer 12 shown in FIG. 6 and Table 3 are all constant except for the TDMASb supply amount, but the composition of the InGaAs layer 12 with the TDMASb supply amount in which the carrier concentration is saturated fluctuated greatly. The degree of lattice mismatch with respect to the InP substrate of the InGaAs layer 12 produced at a TDMASb supply amount (0 to 50 μmol / min) at which the carrier concentration is not saturated was within ± 0.1%, but the TDMASb supply amount was 122.8 μmol / min. The lattice mismatch of the InGaAs layer 12 of 192.6 μmol / min increased to 0.26% and 0.36%, respectively. This is thought to be due to the fact that Sb is excessively present on the growth surface to suppress Ga uptake.

  FIG. 7 shows the relationship between the Sb concentration in the InGaAs layer 12 and the TDMASb supply amount. Although the supplied Sb is taken into the crystal, its amount is small and the composition is 2 at. % (Atomic percentage in group V atoms; here, atomic percentage with As). Further, the amount of Sb taken in and the TDMASb supply amount are in a proportional relationship. That is, the composition was not changed because a large amount of Sb was taken into the InGaAs layer 12 produced at the TDMASb supply rate of 122.8 μmol / min and 192.6 μmol / min, but the ratio of In and Ga was changed. , Indicating that compositional variation occurred.

  When epitaxially growing a multi-element mixed crystal, if the degree of lattice mismatch with the substrate increases, crystal defects occur in the epitaxial layer, which is a major factor that degrades device characteristics. That is, it is practically desirable that the carrier concentration can be controlled while maintaining the composition controllability of the epitaxial film. Under the growth conditions used in this example, the Sb supply amount whose composition did not vary was in the range of greater than 0 and 50 μmol / min. In FIG. 6, this range is the range in which the zinc concentration and carrier concentration in the InGaAs layer 12 increase when the TDMASb supply amount is increased, in other words, until the zinc concentration and carrier concentration in the InGaAs layer 12 are saturated. It is a range. When this range is converted into the Sb concentration (atomic percentage in group V atoms) contained in the InGaAs layer 12, 0 at. % Greater than 0.5 at. % Or less.

On the other hand, under the condition of the growth temperature of 620 ° C. in Example 1, no composition variation occurred over the range of the total Sb supply amount of 0 to 192.6 μmol / min. The Sb concentration in the InGaAs layer 12 at this time is 0.5 at. Over the entire Sb supply range as shown in FIG. % Or less. Therefore, from the results of Example 1 and this example, the Sb concentration contained in the InGaAs layer 12 is 0 at. % Greater than 0.5 at. If the Sb supply amount is within the range of% or less, the supply of Sb increases the zinc concentration and the carrier concentration without causing the composition variation of the InGaAs layer 12, that is, 1 × 10 ¹⁹ cm ⁻³ or more. It was confirmed that a concentration of

  For example, the InGaAs layer 12 was produced at a TDMASb supply amount with no composition variation, and the carrier concentration was evaluated. Specifically, the InGaAs layer 12 was grown by fixing the growth temperature of 540 ° C., the TDMASb supply rate at 18.1 μmol / min, and changing the DEZn supply amount. FIG. 8 and Table 4 show the carrier concentration at each DEZn supply amount of the InGaAs layer 12 manufactured under these conditions.

As shown in FIG. 8 and Table 4, the carrier concentration increased with increasing DEZn supply amount, and when the DEZn supply amount was 72.1 μmol / min, a carrier concentration of 4.65 × 10 ¹⁹ cm ⁻³ was obtained. . Further, it was confirmed that all the InGaAs layers 12 manufactured under these conditions were lattice-matched to InP with no composition variation. That is, in FIG. 6, by using TDMASb in a TDMASb supply amount in a range where the zinc concentration and the carrier concentration are not saturated, that is, in a supply amount in a range greater than 0 and 50 μmol / min or less, the carrier concentration is maintained while maintaining composition controllability. Confirmed that can be increased.

  Although the growth temperature is 540 ° C. in this embodiment, the same effect can be obtained even at a temperature lower than 540 ° C. as long as the raw material used is decomposed on the growth surface. Since raw materials such as DEZn, TDMASb, and other DMZn and TMSb used in this example can be decomposed even at about 400 ° C., the lower limit temperature at which the effect of the present invention can be obtained can be said to be 400 ° C. The upper limit temperature is a temperature at which the crystallinity is not deteriorated due to the detachment of the raw material, and is 800 ° C. in the compound semiconductor film formed on the InP substrate.

  Hereinafter, the cause of the increase in carrier concentration due to the supply of TDMASb in the present invention will be described.

  In crystal growth of a III-V group compound semiconductor that does not contain Sb in the mother crystal, it is known that when a small amount of Sb is supplied during crystal growth, Sb acts as a surfactant. The surfactant itself is hardly taken into the crystal due to the segregation effect, and has the effect of changing only the growth mode on the surface. The effect of Sb in the present invention is also one of the surfactant effects. That is, the present invention traps zinc atoms as impurities, which are usually easily desorbed, by adsorbing Sb atoms on the growth surface (especially steps on the crystal surface or step portions at the atomic layer level called kinks). This utilizes the effect of replacing zinc atoms by the segregation effect and incorporating zinc into the crystal.

  As shown in FIGS. 3 and 6, the zinc concentration (carrier concentration) has a dependency on the TDMASb supply amount because the entire growth surface is covered with Sb atoms so that the supply amount exceeds a certain value. Is necessary. By lowering the growth temperature, the desorption of Sb atoms from the surface can be suppressed, and a large effect of increasing the carrier concentration is obtained with a small amount of TDMASb supply. Moreover, it can be considered that the zinc concentration is saturated with respect to the supply amount because the Sb atoms cover the entire surface.

  Even Sb having a segregation effect is slightly incorporated into the crystal as shown in FIG. However, although the Sb concentration taken into the crystal is proportional to the Sb supply amount (here, TDMASb supply amount), the zinc concentration is not proportional to the Sb supply amount. That is, the effect of increasing the zinc concentration due to the supply of Sb indicates that there is no correlation with the Sb concentration taken into the crystal.

  Although there is no literature regarding materials using InP as a substrate for such an increase in zinc concentration due to the supply of Sb, for example, Non-Patent Document 1 and Non-Patent Documents regarding zinc-doped GaP layers and GaInP layers using GaP as a substrate. 2 and Non-Patent Document 3. In Non-Patent Document 1 and Non-Patent Document 2, the mechanism is reported that a hydrogen atom bonded to a surface Sb atom is incorporated into a crystal in the form of a zinc-hydrogen bond in order to bond with a zinc atom. Has been. This is because, in SIMS analysis, supplying Sb increases the concentration of hydrogen in the crystal as well as the concentration of zinc.

However, in the present invention, as shown in FIG. 6, even when Sb is supplied, the hydrogen concentration in the crystal does not increase, and the mechanism is completely different from the mechanism shown in Non-Patent Documents 1 and 2. Is clear. In FIG. 6, since the hydrogen concentration was below the lower limit of detection of SIMS in all the samples, it was plotted at 2 × 10 ¹⁷ cm ⁻³ . Non-Patent Document 2 reports that although the zinc concentration increases, there is no correlation between the zinc concentration and the carrier concentration. Furthermore, Non-Patent Document 3 explains that the increase in zinc concentration is a surfactant effect of Sb, but there is no correlation between the Sb supply amount and the zinc concentration, and it is reported that the zinc concentration cannot be controlled by the Sb supply amount. doing.

  On the other hand, in the present invention, by supplying Sb, the zinc concentration and the carrier concentration in the compound semiconductor film can be increased at the same time, and the increase amount can be controlled by the Sb supply amount. This conflicts with the content reported in 3. From the above, it is clear that the present invention is based on a mechanism that is completely different from the mechanisms reported in Non-Patent Documents 1 to 3, and therefore, the obtained effects are also different.

(Example 3)
In this example, the zinc-doped InGaAs layer shown in Examples 1 and 2 is used as a contact layer for a non-alloy electrode. The contact resistance between the InGaAs layer and the electrode (Ti / Pt / Au) was determined using a transmission line model (TLM). Further, as an example of the measurement sample of this example, a semi-insulating InP substrate doped with Fe under the conditions of a TDMASb supply amount of 18.1 μmol / min, a DEZn supply amount of 72.1 μmol / min, and a growth temperature of 540 ° C. A zinc-doped InGaAs layer was formed by MOVPE growth. For comparison, a comparative sample made of a zinc-doped InGaAs layer was prepared and measured without supplying TDMASb and under other conditions.

The carrier concentrations of the InGaAs layer of the sample of this example (supplied with TDMASb) and the InGaAs layer of the comparative sample (without supplying TDMASb) are 4.6 × 10 ¹⁹ cm ⁻³ and 2.5 × 10 respectively. ¹⁹ cm ⁻³ . The contact resistivity determined by the TLM method was 4.4 × 10 ⁻⁷ Ωcm ² for the InGaAs layer of the sample of this example, and 1.7 × 10 ⁻⁶ Ωcm ^{2 for} the InGaAs layer of the comparative sample. It was. From this result, it is possible to reduce the contact resistance with the electrode even in the non-alloy process by using the InGaAs layer of the sample of this example, that is, the zinc-doped InGaAs layer prepared by supplying TDMASb, as the contact layer. is there.

  In this embodiment, the InGaAs layer is used as the contact layer, but the same effect can be obtained even if the InGaAsP layer is used.

Example 4
In this embodiment, a semiconductor device, for example, a ridge type distributed feedback (DFB) laser is manufactured using the contact layer shown in the third embodiment. This configuration is shown in FIG. 9, and the present embodiment will be described.

  In the DFB laser of the present embodiment, as shown in FIG. 9, a quantum well structure 22 in which an n-type InP clad layer 20 is sandwiched between InGaAsP optical confinement layers 21 and 23 on an n-type InP (100) substrate 19. Then, a diffraction grating (not shown) is formed on the upper InGaAsP light confinement layer 23 using electron beam exposure and wet etching to produce a DFB structure.

  The quantum well structure 22 has an InGaAlAs quantum well layer (6 nm) with a band gap wavelength of 1.4 μm and a compressive strain of 1%, an InGaAlAs barrier layer (10 nm with a band gap wavelength of 1.0 μm and a tensile strain of 0.2%). ) Has a multiple quantum well structure consisting of 11 layers. Thereafter, the p-type InP clad layer 24 and the InGaAs layer shown in Example 3 are regrown as the contact layer 25.

After the contact layer is grown, an inverted mesa stripe structure having a width of 2.0 μm is produced by using dry etching and wet etching together with the SiO ₂ layer 26 as a mask.

  After embedding the stripe side with polyimide 27, a non-alloy p-type electrode 28 is produced. After the n-type electrode 29 is formed, the resonator length is cleaved to 250 μm, and a ridge type DFB laser structure is fabricated. One end face was coated with a highly reflective film (reflectance of 90% or higher), and the other face was coated with a non-reflective film (reflectance of 1% or lower).

  For comparison, a laser having a different structure only in the contact layer in the ridge type DFB laser structure, that is, a laser using an InGaAs contact layer manufactured without supplying TDMASb was also manufactured.

  In the laser of this example (the one in which the InGaAs contact layer was produced by supplying TDMASb) and the laser in the comparative example (the one in which the InGaAs contact layer was produced without supplying TDMASb), both were in continuous operation at room temperature. Single mode oscillation at a wavelength of 1.312 μm was obtained, the threshold current was about 10 mA, and an optical output of about 30 mW was obtained. However, in the laser of the comparative example, the 3 dB band in the small signal characteristic at room temperature is 15.9 GHz, whereas in the laser of this example, a value of 17.5 GHz was obtained. Further, when the yield of a laser chip capable of obtaining a small signal characteristic of 15 GHz or more was examined, it was 48% with the laser of the comparative example, but 92% with the laser of the present example. From these results, it was confirmed that the laser characteristics can be improved by using the InGaAs contact layer produced by supplying TDMASb.

  In this embodiment, a quantum well structure made of InGaAlAs is used as the active layer of the laser. However, the present invention relates to the formation of a contact layer, and includes an optical confinement layer, a quantum well structure, a method for forming a diffraction grating, and the like. The effect of the present invention can be obtained by using any material / method.

  In this embodiment, a laser having a ridge structure is used. However, the present invention relates to the formation of a contact layer and is not limited to the ridge structure. The same effect as in this embodiment can be obtained also in a semi-insulating embedded laser in which both sides of an active layer are embedded with a semi-insulating InP layer, and in a pn embedded laser in which p-type InP layers and n-type InP layers are alternately stacked. be able to.

(Example 5)
In this embodiment, the contact layer shown in Embodiment 3 is used to manufacture a semiconductor device, for example, a waveguide type light receiving element. This configuration is shown in FIG. 10, and this embodiment will be described.

In the waveguide type light receiving element of this example, as shown in FIG. 10, an n-type InP buffer layer 31 (carrier concentration 2 × 10 ¹⁸ cm) having a thickness of 500 nm is formed on a Fe-doped semi-insulating InP (100) substrate 30. ^-3 ), 100 nm thick n-type InGaAsP contact layer 32 (band gap wavelength 1.3 μm, carrier concentration 4 × 10 ¹⁸ cm ⁻³ ), 300 nm thick n-type InP cladding layer 33 (carrier concentration 2 × 10 ¹⁸ cm ^{−). 3} ), n-type InGaAsP optical confinement layer 34 with a thickness of 800 nm (band gap wavelength 1.3 μm, carrier concentration 2 × 10 ¹⁸ cm ⁻³ ), undoped InGaAs light absorption layer 35 with a thickness of 200 nm, p-type InGaAsP optical confinement with a thickness of 800 nm layer 36 (band gap wavelength 1.3 .mu.m, carrier concentration 1 × 10 ¹⁸ cm ^-3), a 500nm thick p-type InP cladding Layer 37 (carrier concentration ^{1 × 10 18 cm -3),} p -type InGaAs contact layer 38 was produced by supplying a 250nm thick TDMASb (carrier concentration 4 × 10 ¹⁹ cm ^-3), are formed successively.

  Thereafter, a stripe structure having a width of 5 μm and a length of 15 μm was formed by dry etching, and the side thereof was filled with polyimide 39. Finally, a non-alloy p-type electrode 40 and an n-type electrode 41 were prepared.

For comparison, in the waveguide type light receiving element, a light receiving element having a different configuration only in the contact layer, that is, a p-type InGaAs layer (carrier concentration 2.5 × 10 ¹⁹ cm ⁻³ ) manufactured without supplying TDMASb. A waveguide type light receiving element having a contact layer as a contact layer was also fabricated.

  The 3 dB band in the frequency characteristics of the manufactured light receiving element is 40 to 48 GHz in 10 elements in the light receiving element of the comparative example (the contact layer is manufactured without supplying TDMASb), and the average is 43 GHz. there were. On the other hand, in the light receiving element of this example (the contact layer was prepared by supplying TDMASB), the 3 dB band of 10 elements was 50 to 55 GHz, and the average was 52 GHz. From this result, it was confirmed that the characteristics of the light receiving element can be improved by using a contact layer manufactured by supplying TDMASb.

  In this embodiment, the InGaAs layer is used as the light absorption layer and the InGaAsP layer is used as the light confinement layer. However, the present invention relates to the contact layer and is not limited to the structure of the light absorption layer and the light confinement layer. . In this embodiment, the waveguide type light receiving element has been described as an example. However, the same effect can be obtained with a surface type light receiving element.

  The present invention is suitable for a contact layer for a non-alloy electrode of a semiconductor device.

12 InGaAs layer 25 p-InGaAs contact layer 38 p-InGaAs contact layer

Claims (1)

Compound for producing a III-V compound semiconductor film using zinc as a p-type dopant, containing at least one of In, Ga, Al as a group III atom and at least one As, P as a group V atom other than N A method for manufacturing a semiconductor film, comprising:
Supplying trisdimethylaminoantimony or trimethylantimony which is a Sb-containing raw material containing Sb together with a zinc-containing raw material containing zinc;
The growth temperature of the compound semiconductor film is 400 ° C. or more and 540 ° C. or less,
The atomic percentage in the group V atoms of Sb taken into the compound semiconductor film is 0 at. %, 0.5 at. % By controlling the following range, method for producing a compound semiconductor film, characterized in that the zinc concentration and the carrier concentration contained in the compound semiconductor film and 2 × 10 ¹⁹ cm ^-3 or more.

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