JP2005012193A - Semiconductor device and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor device having a III group nitride semiconductor which is capable of improving light emission efficiency by producing a spatial fluctuation in the bandgap of the III group nitride semiconductor. <P>SOLUTION: This semiconductor device comprises an active layer composed by a III group nitride semiconductor layer which contains at least three kinds of elements including aluminum. Wherein the active layer has the spatial fluctuation of a bandgap due to the distribution variations of aluminum composition in the layer. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a semiconductor device made of a nitride compound semiconductor used for a short wavelength semiconductor laser, a light emitting diode or the like, and a method for manufacturing the same.

_{B x Al y Ga z In 1} -xyz N (0 ≦ x ≦ 1,0 ≦ y ≦ 1,0 ≦ z ≦ 1,0 ≦ x + y + z ≦ 1) represented by the group III nitride compound semiconductor (hereinafter, A nitride semiconductor is simply a material that can cover wavelengths from red to ultraviolet. To date, blue light-emitting diodes and green light-emitting diodes have been realized, and nitride-based semiconductors are expected as optical device materials capable of realizing a wider wavelength range in the future.

  In general, nitride-based semiconductor elements are often produced on a sapphire substrate. In this case, since the lattice constants of the nitride semiconductor and sapphire are greatly different, many dislocations exist in the nitride semiconductor film. Nevertheless, high-efficiency light emission can be realized because nitride-based semiconductors have unique properties. That is, since there is a large lattice mismatch between GaN and InN constituting InGaN used as the active layer, GaN and InN are not mixed uniformly, and there is a region where the composition of In is locally large. As a result of the formation, spatial fluctuation (hereinafter simply referred to as fluctuation) occurs in the band gap (see, for example, Patent Document 1). In this manner, in the region where the In composition is large, the potential is smaller than in the peripheral region, and thus electrons or holes are easily confined in the region where the In composition is large. Once the electrons or holes are locally confined, it becomes difficult to be captured by the non-emission center due to dislocations and the like, so that highly efficient light emission is possible.

  In addition, such a nitride-based semiconductor element is usually fabricated by metal organic vapor phase epitaxy or molecular beam epitaxy.

On the other hand, a laser ablation method is known as a method for forming a film on a substrate (see, for example, Patent Document 2). The laser ablation method is a method of forming a film on a substrate by irradiating a material with laser light and evaporating the material.
JP 2001-345478 A JP-A-6-293958

  However, when AlGaN, which is promising as an ultraviolet light source, is used as the active layer, unlike the above-described active layer made of InGaN, the band gap hardly fluctuates. This is because composition variation hardly occurs in the AlGaN layer, so that electrons or holes recombine without contributing to light emission in the non-light emitting center. Therefore, when AlGaN is used as the active layer, fluctuation in the band gap hardly occurs, and the light emission efficiency is lowered.

  In addition, it is still difficult to form a potential region in which electrons or holes are likely to be localized by easily controlling variation in composition in a nitride-based semiconductor (that is, to form fluctuations in a band gap).

  In view of the above, an object of the present invention is to easily control variation in composition in a nitride-based semiconductor and form fluctuations in the band gap of the nitride-based semiconductor. This increases the light emission efficiency of the nitride-based semiconductor device.

  In order to achieve the above object, the present inventor made various studies, and as a result, when a mixed crystal of a nitride-based semiconductor made of InGaN or AlGaN or the like was produced by laser ablation, the composition of these mixed crystals was changed. It was found that fluctuations occurred and fluctuations could be formed in the band gap.

  The present invention has been made in view of the above knowledge. Specifically, a semiconductor device according to the present invention includes a group III nitride semiconductor layer including at least aluminum and having three or more different constituent elements. A semiconductor device comprising an active layer comprising a band gap fluctuation based on a variation in aluminum composition distribution in the active layer.

  According to the semiconductor device of the present invention, the fluctuation of the aluminum composition distribution in the group III nitride semiconductor layer causes fluctuations in the band gap of the active layer. The hole can be confined. For this reason, once electrons or holes are locally confined, it is difficult to be captured by the non-emission center due to dislocations and the like, so that a semiconductor device capable of realizing highly efficient light emission can be obtained.

  A first method for manufacturing a semiconductor device according to the present invention is a method for manufacturing a semiconductor device including an active layer made of a group III nitride semiconductor layer having at least three kinds of constituent elements including at least aluminum. The step of forming the active layer includes a step of forming fluctuations in the band gap of the active layer by varying the distribution of the aluminum composition in the active layer.

  According to the first method for manufacturing a semiconductor device of the present invention, the fluctuation of the aluminum composition in the group III nitride semiconductor layer is made to fluctuate in the band gap of the active layer. It is possible to confine electrons or holes. For this reason, once electrons or holes are locally confined, they are less likely to be captured by the non-emission center due to dislocations and the like, so that a semiconductor device capable of realizing highly efficient light emission can be manufactured.

  In the first method for manufacturing a semiconductor device, in the step of forming the active layer, the target containing the constituent elements of the active layer is evaporated by irradiating a laser to disperse the aluminum composition distribution in the active layer. It is preferable to include the step of making it stick.

  Thus, by laser irradiation, the distribution of aluminum composition in the active layer can be easily dispersed on the order of several nanometers.

  In the first method for manufacturing a semiconductor device, the target is preferably composed of a Group III nitride semiconductor, a Group III metal, or a composition having a composition ratio of Group III elements to Group V elements greater than 1.

  In this way, the distribution of aluminum composition in the active layer can be easily varied.

  In the first method for fabricating a semiconductor device, the step of forming the active layer is preferably performed in a nitrogen atmosphere.

  According to a second method of manufacturing a semiconductor device according to the present invention, a method of manufacturing a semiconductor device comprising a step of forming an active layer made of a group III nitride semiconductor layer, the step of forming an active layer comprising: The first raw material is different from the first raw material after the step of supplying the first raw material containing the constituent elements of the active layer and the step of supplying the first raw material so that the coverage with respect to the formation is less than 1. And a step of supplying a second raw material containing a constituent element of the active layer.

  According to the second method for manufacturing a semiconductor device, since the second raw material is supplied onto the main surface where the coverage of the underlayer is less than 1 by the supply of the first raw material, the composition distribution in the active layer Can be easily dispersed. For this reason, fluctuations can be formed in the band gap of the active layer, so that electrons or holes can be confined in a region having a small band gap. Therefore, once the electrons or holes are locally confined, it becomes difficult to be captured by the non-emission center due to dislocations and the like, so that a semiconductor device capable of realizing highly efficient light emission can be manufactured. Here, the coverage means the ratio of the area of the deposit deposited on the underlayer to the area of the underlayer.

  In the second method for manufacturing a semiconductor device, the step of supplying the first raw material preferably includes a step of supplying a particle group generated by thermally decomposing the first raw material.

  In this way, a raw material can be easily supplied and a film having excellent crystallinity can be formed.

  In the second method for manufacturing a semiconductor device, the step of supplying the second raw material preferably includes a step of supplying a particle group generated by thermally decomposing the second raw material.

  In this way, a raw material can be easily supplied and a film having excellent crystallinity can be formed.

  In the second method for manufacturing a semiconductor device, the particle group preferably includes aluminum as a constituent element.

  In the second method for manufacturing a semiconductor device, the particle group is preferably formed by irradiating a target made of a group III nitride semiconductor with a laser beam and evaporating it.

  In the second method for manufacturing a semiconductor device, the particle group is preferably formed by irradiating a target made of a group III metal with a laser beam and evaporating it.

  In the second method for manufacturing a semiconductor device, the particle group preferably has a composition ratio of a group III element to a group V element that is greater than 1.

  In the second method for fabricating a semiconductor device, the step of forming the active layer is preferably performed in a nitrogen atmosphere.

  According to the semiconductor device and the manufacturing method thereof according to the present invention, the fluctuation of the aluminum composition distribution in the group III nitride semiconductor layer results in fluctuations in the band gap of the active layer. It is possible to confine electrons or holes. For this reason, once electrons or holes are locally confined, it is difficult to be captured by the non-emission center due to dislocations and the like, so that a semiconductor device capable of realizing highly efficient light emission can be obtained.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  First, a specific apparatus to which a semiconductor device manufacturing method according to each embodiment described below can be applied will be described with reference to FIG. 1 as an example.

  FIG. 1 shows a general cross-sectional view of an ultraviolet light emitting diode (LED).

  As shown in FIG. 1, a GaN layer 2 is formed on the sapphire substrate 1. On the GaN layer 2, a clad layer 3 made of an n-AlGaN layer, an active layer 4 made of AlGaN, and a clad layer 5 made of p-AlGaN are sequentially formed. A p-type electrode 6 is formed on the cladding layer 5. An n-type electrode 7 is formed on the cladding layer 3 formed on the GaN layer 2.

  As described above, the light emitting diode shown in FIG. 1 has an AlGaN multilayer structure. As an element having a similar structure, there is a semiconductor laser element (LD), a field effect transistor (FET), a bipolar transistor, or the like in addition to an LED. The semiconductor device manufacturing method described below can be applied to these element manufacturing methods, and relates to the above-described method for manufacturing the active layer 4 made of AlGaN.

  Each embodiment will be specifically described below.

(First embodiment)
A method for manufacturing a semiconductor device according to the present invention will be described below with reference to FIGS. FIG. 2 is a schematic view showing the structure of the laser ablation apparatus. FIG. 3 is a fragmentary process cross-sectional view illustrating the method for manufacturing a semiconductor device according to the present invention.

  First, the laser ablation apparatus will be described.

  As shown in FIG. 2, a susceptor 12 for installing a substrate is installed in a chamber 11, and a heater 13 for heating the substrate is installed. In addition, a plurality of stainless steel target holding disks 14 are installed at positions facing the susceptor 12. By irradiating the target 17 with the laser beam 16 through the quartz optical window 15 from the outside, the raw material is emitted from the target 17. The target holding disk 14 on which the target 17 is placed has a mechanism that rotates about its center.

  Next, a method for manufacturing a semiconductor device according to the present invention using a laser ablation apparatus will be specifically described with reference to FIGS.

First, on the susceptor 12 in the chamber 11 of the laser ablation apparatus, a sapphire substrate 20 having a C-plane with a diameter of 2 inches as a main surface is installed (see FIG. 2). Next, after the chamber 11 is sufficiently evacuated with a vacuum pump, the sapphire substrate 20 is heated to 1050 ° C. Next, nitrogen is introduced into the chamber 11 to keep the degree of vacuum in the chamber 11 at 6.65 × 10 ⁻⁴ Pa. An ArF excimer laser (wavelength 193 nm, energy density 1 J / cm ² , frequency 100 Hz) is used as the laser for laser ablation.

  Next, the target 17 made of GaN is irradiated with laser light 16 (see FIG. 2). In this case, the surface of the target 17 made of GaN is locally and rapidly heated by the laser light 16, so that a particle group called a plume 18 made of electrons, atoms, molecules, ions, or the like is generated. The generated plume 18 reaches the sapphire substrate 20 installed at a position facing the target 17 while colliding with and reacting with nitrogen in the atmosphere, and is recondensed to form a GaN layer 21. That is, a GaN layer 21 having a thickness of 1 μm is formed on the sapphire substrate 20 (see FIG. 3A). In addition, after forming the buffer layer which consists of AlN or GaN on the sapphire substrate 20, before forming the GaN layer 21 on the sapphire substrate 20, the GaN layer 21 may be formed on the buffer layer. Good.

  Next, the heater 13 is heated to increase the temperature of the sapphire substrate 20 to 1200 ° C., and then the target 17 is replaced with a Si-doped n-type AlGaN target having an Al composition of 20%. Thereafter, the target 17 made of n-type AlGaN is irradiated with laser light 16 to evaporate the n-type AlGaN, thereby forming an n-type AlGaN layer 22 having a thickness of 500 nm on the GaN layer 21 (FIG. 3). (See (b)).

  Next, the target 17 is changed from a Si-doped n-type AlGaN target having an Al composition of 20% to a target in which an Al target and an AlGaN target having an Al composition of 10% are each divided in half. . Thereafter, the target 17 is irradiated with the laser beam 16 while rotating the target 17 at a speed of 120 revolutions per minute, whereby an undoped layer having an active layer thickness of 30 nm is formed on the n-type AlGaN layer 22. An AlGaN layer 23a is formed (see FIG. 3C).

  Here, the AlGaN layer 23a will be described in detail.

When the laser beam 16 is irradiated to the Al target that constitutes half of the target 17, the plume 18 scattered from the Al target reacts with nitrogen in the atmosphere from its surroundings, and Al excess AlN _x (0 < x <1) is formed. On the other hand, when the AlGaN target constituting the remaining half of the target 17 is irradiated with the laser beam 16, AlGaN reflecting the composition is formed from the AlGaN target. Therefore, on the n-type AlGaN layer 22, an undoped AlGaN layer 23a in which an Al-excess region exists in the film in nano order is formed. In the vicinity of the Al-excess region, the AlGaN band gap locally increases, so that fluctuation occurs in the band gap of the AlGaN layer 23a. In this way, fluctuations in the Al composition distribution are formed in the order of nanometers in the AlGaN layer 23a, thereby causing fluctuations in the band gap of the AlGaN layer 23a.

  That is, according to the laser ablation method, the laser light 16 converged from the outside of the chamber 11 is introduced through the quartz optical window 15 and irradiated on the surface of the solid raw material (the surface of the target 17) installed in the chamber 11, The raw material is released into the gas phase, and the surface of the raw material is locally heated rapidly by the laser beam 16 to evaporate. For this reason, the composition ratio of the scattered atoms reflects the composition ratio of the target 17 almost without depending on the vapor pressure or the like of each atom constituting the target 17. Therefore, the composition of the elements constituting the active layer (AlGaN layer 23a) can be easily controlled, and variations in the composition distribution can be easily created. Therefore, fluctuations are easily formed in the band gap of the active layer (AlGaN layer 23a). be able to. Moreover, since the raw material used for the laser ablation method can be filled in a plurality of apparatuses, the raw material can be easily changed, and the occurrence of mutual contamination can be prevented.

  Here, as a method for forming the variation in Al composition distribution in the AlGaN layer 23a, the following method is also conceivable.

  That is, an element constituting the AlGaN layer 23a, for example, a raw material containing Al is supplied onto the n-type AlGaN layer 22 so that the coverage with respect to the n-type AlGaN layer 22 which is the underlying layer is less than 1. Next, a raw material containing AlGaN is supplied to form the AlGaN layer 23. In this way, fluctuations in the band gap of the AlGaN layer 23a can be caused by forming variations in the Al composition distribution in the AlGaN layer 23a in the nano order.

  Next, the target 17 is replaced with a target made of p-type AlGaN having an Al composition of 20% from a target in which an Al target and an AlGaN target having an Al composition of 10% are arranged in half. By irradiating the p-type AlGaN target with laser light 16 and evaporating the p-type AlGaN, a p-type AlGaN layer 24 having a film thickness of 500 nm is formed on the AlGaN layer 23a (see FIG. 3D). . As described above, a double heterostructure as shown in FIG.

  When an electrode as shown in FIG. 1 is formed on the element having a double hetero structure as shown in FIG. 3D and a voltage is applied, an Al-excess region is formed in the AlGaN layer 23a. Compared with the case where it was not performed, the light emission intensity of about 10 times was able to be obtained.

  As described above, according to the first embodiment of the present invention, fluctuations in the band gap of the AlGaN layer 23a occur by varying the Al composition distribution in the AlGaN layer 23a as the active layer. For this reason, since electrons or holes are localized at a low potential in the fluctuation of the band gap, they are not easily captured by the non-light emitting center. Therefore, improvement in luminous efficiency can be realized. Further, by forming the AlGaN layer 23a using the laser ablation method, the distribution of the Al composition in the AlGaN layer 23a can be easily varied.

  In the present embodiment, when the AlGaN layer 23a is formed, a target in which the Al target and the AlGaN target are each divided in half is used as the target 17, but the Ga target and the AlGaN target are each divided in half. You may use the target arranged in this way. In this case, a nano-order Ga-rich region is formed in the AlGaN layer, and the band gap of the AlGaN layer is locally reduced in the vicinity of the Ga-rich region. As described above, even when the target in which the Ga target and the AlGaN target are each divided in half is used, fluctuations can be formed in the band gap of the AlGaN layer. Moreover, although the Al target or the Ga target was used as the metal target constituting half of the target 17, the metal target is not limited to one type, and both Al and Ga metals are used. Also good.

  Further, in the present embodiment, when forming the AlGaN layer 23a, a target in which two types of targets are divided and arranged in half is used. However, the dividing ratio may not be equal, and an excessive amount can be obtained by changing the ratio. The density of the region can also be changed.

  Further, when forming the AlGaN layer 23a, it is possible to change the density of the Al-excess region by adjusting the dilution of the nitrogen atmosphere gas. That is, by increasing the ratio of a rare gas such as He or Ne, metal atoms can be supplied without reacting with the nitrogen atmosphere gas. In a complete noble gas atmosphere, metal atoms are supplied as they are, so that metal droplets are formed in the film.

(Second Embodiment)
A method for manufacturing a semiconductor device according to the second embodiment of the present invention will be described below with reference to FIGS. 2 and 3 (a) to 3 (d).

  First, in the semiconductor device manufacturing method according to the second embodiment of the present invention, the GaN layer 21 and the n-type AlGaN are formed on the sapphire substrate 20 by the laser ablation method as in the first embodiment. The layer 22 is formed in order (see FIGS. 3A and 3B).

Next, as the target 17, a target in which an Al _x Ga _1-x N (x = 0.0095) target and an Al _y Ga _1-y N (y = 0.01) target are respectively divided in half is arranged. Use. Then, by irradiating the laser beam 16 while rotating the target 17 at a speed of 120 revolutions per minute, an undoped AlGaN layer 23b having a film thickness of 30 nm is formed on the n-type AlGaN layer 22 ( (See Figure 3 (c)). By using the target 17 made of two types of nitride semiconductors having different compositions, an undoped AlGaN layer 23b in which two types of nitride semiconductors are mixed can be formed. That is, the AlGaN layer 23b is a layer in which Al _x Ga _1-x N (x = 0.0095) and Al _y Ga _1-y N (y = 0.01) are mixed, and has a composition locally. Since the different regions are formed in nano order, the AlGaN layer 23b has a band gap fluctuation reflecting the band gaps of two types of nitride semiconductors. In this manner, fluctuation in the Al composition distribution is formed in the AlGaN layer 23b, thereby causing fluctuation in the band gap of the AlGaN layer 23b.

Next, as a target 17, an Al _x Ga _1-x N (x = 0.0095) target and an Al _y Ga _1-y N (y = 0.01) target are each divided into two halves. The target is made of p-type AlGaN having an Al composition of 20%. By irradiating the p-type AlGaN target with the laser beam 16 and evaporating the p-type AlGaN, the p-type AlGaN layer 24 having a thickness of 500 nm is formed on the AlGaN layer 23b (see FIG. 3D). . As described above, the double heterostructure shown in FIG.

  Here, when a voltage is applied to the device having the double hetero structure as described above after the electrodes as shown in FIG. 1 are formed, it is compared with the case where one type of AlGaN target is used as the target 17. Thus, it was possible to obtain about 10 times the emission intensity. This is because local band gap fluctuations occur in the undoped AlGaN layer 23b as the active layer, so that electrons or holes are localized and are not easily captured by the non-light-emitting center, thereby increasing the light emission efficiency. .

  As described above, according to the second embodiment of the present invention, fluctuations in the band gap of the AlGaN layer 23b occur by varying the Al composition distribution in the AlGaN layer 23b as the active layer. For this reason, since electrons or holes are localized at a low potential in the fluctuation of the band gap, they are not easily captured by the non-light emitting center. Therefore, improvement in luminous efficiency can be realized. Further, by forming the AlGaN layer 23b using the laser ablation method, the distribution of the Al composition in the AlGaN layer 23b can be easily varied.

  Further, in the present embodiment, when the AlGaN layer 23b is formed, a target in which two types of targets are divided and arranged in half is used. However, the ratio of division may not be equal, and by changing the ratio The density of the excess region can also be changed.

  Further, when forming the AlGaN layer 23b, the density of the Al-excess region can be changed by adjusting the dilution of the nitrogen atmosphere gas. That is, by increasing the ratio of a rare gas such as He or Ne, metal atoms can be supplied without reacting with the nitrogen atmosphere gas. In a complete noble gas atmosphere, metal atoms are supplied as they are, so that metal droplets are formed in the film.

(Third embodiment)
A method for manufacturing a semiconductor device according to the third embodiment of the present invention will be described below with reference to FIGS. 2 and 3 (a) to 3 (d).

  First, in the semiconductor device manufacturing method according to the third embodiment of the present invention, the GaN layer 21 and the n-type AlGaN are formed on the sapphire substrate 20 by the laser ablation method as in the first embodiment. The layer 22 is formed in order (see FIGS. 3A and 3B).

Next, an Al _0.10 Ga _0.90 N _0.98 target whose stoichiometry is shifted due to nitrogen deficiency is used as the target 17. That is, the chemical composition ratio of the group III atom to the group V atom is usually 1, but since the nitrogen is deficient, the chemical composition ratio of the group III atom to the group V atom is smaller than 1. By irradiating the laser beam 16 while rotating the target 17 at a speed of 120 revolutions per minute, an undoped AlGaN layer 23c having a film thickness of 30 nm is formed. In this case, the plume 18 generated by irradiating the target 17 with the laser beam 16 reacts with nitrogen in the atmosphere gas from its tip to make up for the nitrogen deficiency. On the other hand, since the central portion of the plume 18 is shielded from the atmospheric gas, it remains in a state deficient in nitrogen. Accordingly, the AlGaN layer 23c is formed as a film in which a region supplemented with a nitrogen deficiency and a region lacking nitrogen are mixed. In this way, fluctuations in the Al gap distribution of the AlGaN layer 23c are caused by forming the dispersion of the Al composition distribution in the nano order in the AlGaN layer 23c.

Next, the Al _0.10 Ga _0.90 N _0.98 target whose stoichiometry is shifted due to nitrogen deficiency is replaced with a target made of p-type AlGaN having an Al composition of 20%. By irradiating the p-type AlGaN target with laser light 16 and evaporating the p-type AlGaN, a p-type AlGaN layer 24 having a film thickness of 500 nm is formed on the AlGaN layer 23c (see FIG. 3D). . As described above, the double heterostructure shown in FIG.

  Here, when an electrode as shown in FIG. 1 is formed on the element having the double hetero structure as described above and a voltage is applied, a normal AlGaN target having no deviation in stoichiometry is obtained as the target 17. Compared with the case of using, about 10 times the emission intensity could be obtained. This is because local band gap fluctuations occur in the AlGaN layer 23c as the active layer, so that electrons or holes are localized and are not easily captured by the non-emission center, thereby increasing the luminous efficiency.

  As described above, according to the third embodiment of the present invention, fluctuations in the band gap of the AlGaN layer 23c occur by varying the Al composition distribution in the AlGaN layer 23c as the active layer. For this reason, since electrons or holes are localized at a low potential in the fluctuation of the band gap, they are not easily captured by the non-light emitting center. Therefore, improvement in luminous efficiency can be realized. Further, by forming the AlGaN layer 23c using the laser ablation method, the distribution of the Al composition in the AlGaN layer 23c can be easily varied.

  In each of the above embodiments, the case where a series of film formation is performed by the laser ablation method has been described. However, other film formation methods may be used. For example, the MOVPE method or the MBE method is used and the raw materials are alternately supplied. However, the present invention can be similarly implemented.

  Moreover, although the case where the ArF excimer laser is used as the laser for laser ablation has been described, other ultraviolet lasers may be used. For example, an excimer laser such as XeCl (wavelength 308 nm) or KrF (wavelength 248 nm), or the fourth harmonic (wavelength 266 nm) of a YAG laser may be used.

Further, the description has been given of the case of using an AlGaN layer as an active _{layer, B x Al y Ga z In} 1-xyz N (0 ≦ x ≦ 1,0 ≦ y ≦ 1,0 ≦ z ≦ 1,0 ≦ x + y + z ≦ The present invention can be similarly implemented even with an active layer comprising 1).

  As described above, the present invention is useful for a semiconductor device having a nitride semiconductor multilayer structure, such as an LED, a semiconductor laser element (LD), a field effect transistor (FET), or a bipolar transistor.

1 is a structural cross-sectional view of an ultraviolet light emitting diode (LED) as an example of a semiconductor device to which a semiconductor device manufacturing method according to each embodiment of the present invention can be applied. It is a schematic sectional drawing of the laser ablation apparatus utilized with the manufacturing method of the semiconductor device concerning each embodiment of the present invention. It is principal part process sectional drawing which shows the manufacturing method of the semiconductor device which concerns on each embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Sapphire substrate 2 GaN layer 3 n-cladding layer 4 active layer 5 cladding layer 6 p-type electrode 7 n-type electrode 11 chamber 12 susceptor 13 heater 14 target holding disk 15 quartz optical window 16 laser light 17 target 20 sapphire substrate 21 GaN layer 22 n-type AlGaN layers 23a, 23b, 23c Undoped AlGaN layer 24 p-type AlGaN layer

Claims (13)

A semiconductor device comprising an active layer made of a group III nitride semiconductor layer containing at least aluminum and having three or more different constituent elements,
The active layer is
A semiconductor device characterized by having a band gap fluctuation based on variation in the distribution of the aluminum composition in the active layer. A method for manufacturing a semiconductor device comprising an active layer comprising a group III nitride semiconductor layer containing at least three kinds of constituent elements including at least aluminum,
The step of forming the active layer includes:
A method of manufacturing a semiconductor device, comprising the step of forming fluctuations in a band gap of the active layer by varying the distribution of the aluminum composition in the active layer. The step of forming the active layer includes:
3. The method according to claim 2, further comprising a step of varying a distribution of the composition of the aluminum in the active layer by irradiating the target containing the constituent elements of the active layer with a laser and evaporating the target. Semiconductor device manufacturing method.   The semiconductor device according to claim 3, wherein the target is made of a group III nitride semiconductor, a group III metal, or a composition having a composition ratio of a group III element to a group V element larger than 1. Method.   3. The method of manufacturing a semiconductor device according to claim 2, wherein the step of forming the active layer is performed in a nitrogen atmosphere. A method of manufacturing a semiconductor device including a step of forming an active layer made of a group III nitride semiconductor layer,
The step of forming the active layer includes:
Supplying a first raw material containing the constituent elements of the active layer so that the coverage of the underlayer is less than 1,
And a step of supplying a second raw material different from the first raw material and including a constituent element of the active layer after the step of supplying the first raw material. Device manufacturing method.   The method for manufacturing a semiconductor device according to claim 6, wherein the step of supplying the first raw material includes a step of supplying a particle group generated by thermally decomposing the first raw material.   The method of manufacturing a semiconductor device according to claim 6, wherein the step of supplying the second raw material includes a step of supplying a particle group generated by thermally decomposing the second raw material.   The method for manufacturing a semiconductor device according to claim 7, wherein the particle group includes aluminum as a constituent element.   9. The method of manufacturing a semiconductor device according to claim 7, wherein the particle group is formed by irradiating a target made of a group III nitride semiconductor with laser light to evaporate the target.   The method of manufacturing a semiconductor device according to claim 7, wherein the particle group is formed by irradiating a target made of a group III metal with a laser beam and evaporating the target.   9. The method of manufacturing a semiconductor device according to claim 7, wherein the particle group has a composition ratio of a group III element to a group V element that is greater than 1.   The method of manufacturing a semiconductor device according to claim 6, wherein the step of forming the active layer is performed in a nitrogen atmosphere.

Images