JP4186306B2 - Semiconductor device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a light emitting device such as a light emitting diode or a semiconductor laser, and a semiconductor device containing nitrogen such as a transistor.
[0002]
[Prior art]
Nitrogen compounds (hereinafter referred to as nitride) semiconductors such as GaN, InN, and AlN are violet semiconductor laser devices used in high-density optical information recording devices and the like, and visible light emission that emits light such as purple, blue, and green Suitable as a diode material.
[0003]
FIG. 13 shows a conventional light emitting device using a nitride semiconductor (Japanese Patent Laid-Open No. 9-153642), which will be described with reference to FIG.
[0004]
This conventional semiconductor device includes a polycrystalline or amorphous GaN buffer layer 2, an n-type (hereinafter referred to as n-) GaN cladding layer 3, an InGaN active layer 4, a p-type (hereinafter referred to as p-) on a sapphire substrate 1. ) A GaAlN cladding layer 5 and a p-GaN contact layer 6 are sequentially stacked.
[0005]
In a nitride semiconductor, InGaN has a smaller band gap than GaN, and AlGaN has a larger band gap than GaN. Therefore, the light emitting element has a configuration in which InGaN is an active layer and AlGaN is a cladding layer.
[0006]
[Problems to be solved by the invention]
Such a conventional semiconductor device has the following two problems.
[0007]
That is, since the vapor pressure of nitrogen in the nitride semiconductor is high, nitrogen vacancy (vacancies, hereinafter referred to as nitrogen vacancy) is likely to occur when the nitride semiconductor layer is formed. ¹⁵ cm ^-3 There was a problem that a certain amount of nitrogen bakery was generated, which became a seed of defects and formed a deep level to absorb light emission, thereby reducing the light emission efficiency of the semiconductor device.
[0008]
In addition, since the lattice constant of InGaN is larger than the lattice constant of GaN, the InGaN active layer is distorted, and an internal electric field is generated in the InGaN active layer due to the piezo effect. As a result, they are concentrated and distributed on the opposite sides in the active layer, and as a result, the probability of bonding of electrons and holes in the active layer is lowered and the luminous efficiency of the semiconductor device is lowered. Therefore, there are problems that the characteristics of the semiconductor device are deteriorated, the operating current is increased, and the reliability is deteriorated.
[0009]
The present invention has been made in view of the circumstances as described above. In a semiconductor device using a nitride semiconductor, the number of nitrogen vacancy in each layer is reduced, and the piezoelectric effect due to strain applied to each layer is reduced to reduce the piezo effect. It is an object to provide a semiconductor device having high reliability with an operating current.
[0010]
[Means for Solving the Problems]
The semiconductor device of the present invention includes a substrate and a semiconductor layer formed on the substrate, and the semiconductor layer includes one or more elements selected from the group consisting of boron, aluminum, gallium, and indium; It consists of a compound consisting of one or more elements selected from the group consisting of phosphorus, arsenic and antimony and nitrogen, and the total number of atoms of phosphorus, arsenic and antimony contained in the compound is contained in the compound It is smaller than the number of nitrogen atoms.
[0011]
With this configuration, phosphorus, arsenic, and antimony have an equilibrium vapor pressure at the same temperature lower than that of nitrogen. Thus, a semiconductor device having a semiconductor layer that can be filled with nitrogen and has almost no nitrogen vacancy is obtained.
[0012]
In the semiconductor device of the present invention, the total number of atoms of phosphorus, arsenic and antimony contained in the compound is 25% or less of the number of nitrogen atoms contained in the compound.
[0013]
With this configuration, it is possible to suppress a decrease in the band gap of the semiconductor layer and improve the light emission efficiency of the semiconductor device.
[0014]
The semiconductor device of the present invention has a semiconductor element formed on a semiconductor layer with such a configuration.
[0015]
With this configuration, since the semiconductor element is formed on the semiconductor layer having almost no nitrogen vacancy, a semiconductor device with stable operation can be obtained.
[0016]
The semiconductor device of the present invention has a substrate and a double heterostructure formed on the substrate, and the double heterostructure includes a first cladding layer, an active layer, and a second layer formed from the substrate side. One or more elements selected from the group consisting of boron, aluminum, gallium, and indium, wherein the cladding layer includes at least one of the first cladding layer, the active layer, and the second cladding layer. And the total number of atoms of phosphorus, arsenic and antimony contained in the compound and one or more elements selected from the group consisting of phosphorus, arsenic and antimony, and nitrogen. It is smaller than the number of nitrogen atoms contained therein.
[0017]
With this configuration, phosphorus, arsenic and antimony have an equilibrium vapor pressure lower than that of nitrogen at the same temperature. Therefore, when a semiconductor layer is grown at a high temperature, nitrogen vacancy generated in the semiconductor layer is filled with either phosphorus, arsenic or antimony. If it is used for all the layers of the double hetero structure, it is possible to eliminate the deep level in the first or second cladding layer and to generate almost no defects in the active layer. A highly reliable semiconductor device can be obtained.
[0018]
In the semiconductor device of the present invention, the total number of atoms of phosphorus, arsenic and antimony contained in the compound is 25% or less of the number of nitrogen atoms contained in the compound.
[0019]
With this configuration, a reduction in the band gap of the semiconductor layer can be suppressed, and the light emission efficiency of the semiconductor device can be improved.
[0020]
In the semiconductor device of the present invention, an active layer is formed of the above compound with respect to such a configuration.
[0021]
With this configuration, the nitrogen vacancy in the active layer can be filled with either phosphorous, arsenic, or antimony, so that almost no nitrogen vacancy is generated in the active layer and the electric field in the active layer is relaxed to emit light from the semiconductor device. Efficiency can be improved.
[0022]
In the semiconductor device of the present invention, the first clad layer is Al of the first conductivity type. _x1 Ga _1-x1 N (0 ≦ x1 ≦ 1), and the active layer is made of Al _a Ga _b In _c N _1-z As _z Or Al _a Ga _b In _c N _1-z P _z (0 ≦ a, b, c ≦ 1, 0 <z ≦ 0.2, a + b + c = 1) at least one layer, and the second cladding layer is opposite to the first conductivity type Second conductivity type Al having conductivity type _x2 Ga _1-x2 N (0 ≦ x2 ≦ 1).
[0023]
With this configuration, the nitrogen vacancy in the active layer can be filled with arsenic or phosphorus, so that almost no nitrogen vacancy is generated in the active layer, and arsenic or phosphorus has properties such as electronegativity compared to nitrogen. Since it is close to Ga or In, almost no piezo electric field is generated in the active layer, the electric field inside the active layer can be further relaxed, and the light emission efficiency of the semiconductor device can be improved.
[0024]
In the semiconductor device of the present invention, the first clad layer is Al of the first conductivity type. _x1 Ga _1-x1 N (0 ≦ x1 ≦ 1), and the active layer is made of Al _a Ga _b In _c N _1-z1 As _z1 Or Al _a Ga _b In _c N _1-z1 P _z1 (0 ≦ a, b, c ≦ 1, 0 <z1 ≦ 0.2, a + b + c = 1) including at least one layer, and the second cladding layer has a conductivity type opposite to the first conductivity type Al of the second conductivity type having _x2 Ga _1-x2 N (0 ≦ x2 ≦ 1), and has a band gap larger than the energy of light emitted from the active layer on the second cladding layer, and has a first conductivity type or a high resistance. Al _y Ga _1-y N _1-z2 As _z2 Or Al _y Ga _1-y N _1-z2 P _z2 (0 ≦ y ≦ 1, 0 <z2 ≦ 0.2) is formed, a stripe-shaped window is formed in the current block layer, and the current block layer includes the stripe-shaped window. On top of the second conductivity type Al _x3 Ga _1-x3 A third cladding layer made of N (0 ≦ x3 ≦ 1) is formed, and a relationship of 0 ≦ X1, X2, X3 <y is established.
[0025]
With this configuration, the nitrogen vacancy in the active layer and the current blocking layer can be filled with arsenic or phosphorus, so that the reactive current is reduced and a low operating current and high efficiency semiconductor device can be obtained.
[0026]
The semiconductor device according to the present invention includes the stripe-shaped window and has an effective refractive index n1 in a direction perpendicular to the main surface of the active layer, does not include the stripe-shaped window, and the active When the effective refractive index in the direction perpendicular to the main surface of the layer is n2, n2 <n1 and 3 × 10 ^-3 ≦ n1-n2 ≦ 8 × 10 ^-3 The relationship is established.
[0027]
With this configuration, an astigmatic difference of 5 μm or less is obtained, and a higher-order mode is cut off. In particular, during high-power operation, a semiconductor device having a stable lateral mode can be obtained by suppressing spatial hole burning.
[0028]
In the semiconductor device of the present invention, the second conductivity type is p-type and a barrier layer having a larger band gap than the second cladding layer is inserted between the active layer and the second cladding layer. It is.
[0029]
With this configuration, since a barrier layer having a larger band gap than the second cladding layer is provided between the active layer and the second cladding layer, carrier diffusion from the active layer to the second cladding layer is suppressed. And the light emission efficiency of the semiconductor device can be increased.
[0030]
In the semiconductor device of the present invention, the barrier layer is made of Al in such a configuration. _a1 Ga _b1 In _c1 N _1-z1 As _z1 Or Al _a1 Ga _b1 In _c1 N _1-z1 P _z1 (0 ≦ a1, b1, c1 ≦ 1, 0 <z1 ≦ 0.2, a1 + b1 + c1 = 1).
[0031]
With this configuration, the nitrogen vacancy in the barrier layer can be filled with arsenic or phosphorus, so that the light emission efficiency can be further improved.
[0032]
In the semiconductor device of the present invention, the first conductivity type is p-type and a barrier layer having a larger band gap than the first cladding layer is inserted between the active layer and the first cladding layer. It is.
[0033]
With this configuration, since a barrier layer having a larger band gap than the first cladding layer is provided between the active layer and the first cladding layer, carrier diffusion from the active layer to the first cladding layer is suppressed. And the light emission efficiency of the semiconductor device can be increased.
[0034]
In the semiconductor device of the present invention, the barrier layer is made of Al in such a configuration. _a1 Ga _b1 In _c1 N _1-z1 As _z1 Or Al _a1 Ga _b1 In _c1 N _1-z1 P _z1 (0 ≦ a1, b1, c1 ≦ 1, 0 <z1 ≦ 0.2, a1 + b1 + c1 = 1).
[0035]
With this configuration, the nitrogen vacancy in the barrier layer can be filled with arsenic or phosphorus, so that the light emission efficiency can be further improved.
[0036]
DETAILED DESCRIPTION OF THE INVENTION
(Embodiment 1)
FIG. 1 is a cross-sectional view of the semiconductor device according to the first embodiment of the present invention.
[0037]
In this structure, a semiconductor layer 8 made of GaN containing arsenic (hereinafter referred to as GaN (As)) is formed on a substrate 7 such as sapphire, and an active element of a field effect transistor or a bipolar transistor is formed on the semiconductor layer 8. Alternatively, a passive element semiconductor element (not shown) such as a capacitor or a resistor is formed. Here, the amount of nitrogen and arsenic contained in the compound forming the semiconductor layer 8 is larger than that of arsenic.
[0038]
With this structure, since the equilibrium vapor pressure at the same temperature is lower than that of nitrogen, arsenic can fill nitrogen vacancy generated in the semiconductor layer 8 with arsenic when GaN (As) is grown at a high temperature. A semiconductor device having almost no semiconductor layer 8 can be obtained, the operation of the semiconductor device can be stabilized at high temperatures, and the reliability of the semiconductor device can be improved.
[0039]
It should be noted that the amount of arsenic contained in the semiconductor layer 8 may be a little larger than the degree of filling the nitrogen vacancy.
[0040]
Further, instead of containing arsenic in the semiconductor layer 8, either phosphorus or antimony may be included, or two or more elements of phosphorus, arsenic and antimony may be included in the semiconductor layer 8. An effect is obtained.
[0041]
Furthermore, the same effect can be obtained even if the semiconductor layer 8 contains one or more elements of boron, aluminum, gallium, and indium.
[0042]
(Embodiment 2)
FIG. 2 is a cross-sectional view of a semiconductor laser device according to the second embodiment of the present invention.
[0043]
In this structure, a GaN (As) buffer layer 10 and an n-GaN (As) contact layer 11 are formed on a sapphire substrate 9, and a Si-doped n-Ga is formed thereon. _0.9 Al _0.1 N (As) first cladding layer 12, undoped In _0.2 Ga _0.8 N (As) / In _0.01 Ga _0.99 N (As) quantum well active layer 13 and Mg-doped p-Ga _0.9 Al _0.1 A second clad layer 14 of N (As) is laminated, and a contact layer 15 of Mg-doped p-GaN (As) is formed thereon. Here, the amounts of nitrogen and arsenic contained in the compounds forming the buffer layer 10, the contact layer 11, the n-type first cladding layer 12, the active layer 13, the p-type second cladding layer 14 and the contact layer 15. Nitrogen is more than arsenic.
[0044]
With this structure, the n-type first cladding layer 12, the active layer 13, the p-type second cladding layer 14 and the contact layer 15 contain arsenic, and arsenic has an equilibrium vapor pressure at the same temperature as that of nitrogen. Since it is low, nitrogen vacancy existing in these semiconductor layers can be filled with arsenic, and the deep levels in the n-type first cladding layer 12 and the p-type second cladding layer 14 can be almost eliminated. At the same time, a semiconductor laser device having the active layer 13 having almost no nitrogen vacancy can be obtained, and a highly efficient and highly reliable semiconductor device can be obtained.
[0045]
Instead of containing arsenic in at least one of the buffer layer 10, the contact layer 11, the n-type first cladding layer 12, the active layer 13, the p-type second cladding layer 14 and the contact layer 15, Similar effects can be obtained by including either phosphorus or antimony, or by including two or more elements of phosphorus, arsenic and antimony.
[0046]
Further, at least one of the buffer layer 10, the contact layer 11, the n-type first clad layer 12, the active layer 13, the p-type second clad layer 14, and the contact layer 15 has boron, aluminum, gallium, and The same effect can be obtained by including any one or more elements of indium.
[0047]
Next, a method for manufacturing this semiconductor laser device will be described with reference to FIG. First, trimethylgallium, trimethylaluminum, trimethylindium, ammonia, arsine (AsH) are grown on the sapphire substrate 9 by a metal organic chemical vapor deposition (MOCVD) method. _Three ) Is used to manufacture the buffer layer 10 of n-GaN (As) (FIG. 3A).
[0048]
Next, n-GaN (As) is grown as a contact layer 11 to a thickness of 1 μm at a crystal growth temperature of 1000 ° C. (hereinafter referred to as growth temperature). The amount of arsenic added at this time is about 10% for nitrogen bakery at a growth temperature of 1000 ° C. ¹⁵ cm ^-3 So about 10 ¹⁵ cm ^-3 What is necessary is just to be a grade (FIG. 3B).
[0049]
Thereafter, Si-doped n-Ga at a growth temperature of 1000 ° C. _0.9 Al _0.1 An N (As) first cladding layer 12 is grown to a thickness of 0.5 μm, and then the growth temperature is lowered to 800 ° C. to form an active layer 13 of undoped In _0.2 Ga _0.8 N (As) / In _0.01 Ga _0.99 An active layer 13 having a quantum well structure of N (As) is grown (the thickness of each layer is 5 nm to form a triple quantum well structure), the growth temperature is raised to 1000 ° C. again, and Mg-doped p-Ga _0.9 Al _0.1 A second cladding layer 14 of N (As) is grown to a thickness of 0.5 μm.
[0050]
Finally, the semiconductor laser device is completed by growing the Mg-doped p-GaN (As) contact layer 15 to a thickness of 0.1 μm (FIG. 3C).
[0051]
For GaN, when the growth temperature is 600 ° C., 800 ° C., and 1000 ° C., the density of nitrogen bakery is about 10 respectively. ¹⁹ cm ^-3 , About 10 ¹⁷ cm ^-3 And about 10 ¹⁵ cm ^-3 Therefore, nitrogen bakery can be filled by adding arsenic in an amount corresponding to these values.
[0052]
In the first and second embodiments, a highly efficient and highly reliable semiconductor device or semiconductor laser device is obtained by using a layer made of GaN (As) having almost no nitrogen vacancy in the semiconductor device or semiconductor laser device. Explained that you can. This layer made of GaN (As) having almost no nitrogen vacancy can be used as a layer constituting a transistor. In such a case, the characteristics of the transistor in a high frequency region can be improved, and the efficiency is high. A reliable transistor can be obtained.
[0053]
(Embodiment 3)
FIG. 4 is a cross-sectional view of a blue light-emitting diode device according to the third embodiment of the present invention.
[0054]
In this structure, an n-GaN layer 17 having a thickness of 1 μm and an n-Al layer having a thickness of 0.5 μm are formed on an n-GaN substrate 16. _0.1 Ga _0.9 First cladding layer 18 made of N, undoped Al with a thickness of 10 nm _0.01 Ga _0.89 In _0.1 N _1-z As _z Active layer 19 made of (0 <z ≦ 0.2), 0.5 μm thick p-Al _0.1 Ga _0.9 A second clad layer 20 made of N and a contact layer 21 made of p-GaN having a thickness of 0.1 μm are formed.
[0055]
With this structure, the nitrogen vacancy in the active layer 19 can be filled with arsenic, so that almost no nitrogen vacancy is generated in the active layer 19 and the electric field inside the active layer 19 is relaxed to improve the luminous efficiency of the blue light emitting diode device. Can be improved. In particular, arsenic has properties such as electronegativity that are close to those of Al, Ga, or In as compared with nitrogen, so that it hardly generates a piezoelectric field in the active layer 19 and improves the light emission efficiency of the blue light emitting diode device. it can. Furthermore, since the proportion of arsenic in nitrogen and arsenic in the active layer 19 is 25% or less of the proportion of nitrogen, the reduction of the band gap of the active layer 19 can be suppressed, and the luminous efficiency of the blue light emitting diode device can be improved. Can be improved.
[0056]
As a manufacturing method of this blue light emitting diode device, the MOCVD method similar to that of the second embodiment is used. The n-GaN layer 17 is introduced to form an active layer 19 having good crystallinity on the n-GaN substrate 16, and the contact layer 21 is a contact resistance of the electrode on the p-type side. It was introduced to reduce this.
[0057]
FIG. 5 shows the relationship between the composition ratio z of As in the active layer 19 and the light emission efficiency of the blue light emitting diode device. The value of luminous efficiency when z = 0 is 1, and z = 0 represents the case of a conventional blue light emitting diode device.
[0058]
According to FIG. 5, it can be seen that the luminous efficiency is improved over the conventional range in the range of 0 <z ≦ 0.2. More specifically, the reason why the light emission efficiency is increased in the case of 0 <z ≦ 0.001 is considered to be that the level of absorbing light emission is reduced by introducing As into the N vacancy. In the vicinity of z = 0.001, the improvement in luminous efficiency is once saturated. The luminous efficiency is improved again in a higher region, which is considered to be because the piezo effect is alleviated by the introduction of As. This is because As has properties such as electronegativity close to that of Al, Ga, and In as compared with N, so that a piezo electric field hardly occurs. It has been found that the light emission efficiency of the blue light emitting diode device decreases in the region of 0.1 <z, and the light emission efficiency becomes lower than the conventional one in the region of 0.2 <z. This is presumably because the band gap of the active layer 19 suddenly decreases in the region of 0.1 <z, particularly 0.2 <z, and exhibits metallic properties.
[0059]
(Embodiment 4)
The blue light-emitting diode device according to the fourth embodiment of the present invention has an active layer 19 of the semiconductor device according to the third embodiment formed of Al with a thickness of 10 nm. _0.01 Ga _0.89 In _0.1 N _1-z P _z (0 <z ≦ 0.2) layer. Also, instead of arsine, phosphine (PH _Three ) Was used.
[0060]
With this structure, the nitrogen vacancy in the active layer 19 can be filled with phosphorus, so that almost no nitrogen vacancy is generated in the active layer 19 and the electric field inside the active layer 19 is relaxed to improve the luminous efficiency of the blue light emitting diode device. Can be improved. In particular, since phosphorus has properties such as electronegativity that are close to those of Al, Ga, or In as compared with nitrogen, it hardly causes a piezoelectric field in the active layer 19 and improves the light emission efficiency of the blue light emitting diode device. it can. Furthermore, since the proportion of nitrogen in the active layer 19 is 25% or less of the proportion of nitrogen, the reduction of the band gap of the active layer 19 can be suppressed, and the luminous efficiency of the blue light emitting diode device can be improved. Can be improved.
[0061]
The relationship between the P composition ratio z in the active layer 19 and the light emission efficiency of the blue light emitting diode device is almost the same as that in FIG. 5, and it was found that the light emission efficiency can be improved even when phosphorus is used. It has been found that the light emission efficiency of the blue light emitting diode device decreases in the region of 0.1 <z, and the light emission efficiency becomes lower than the conventional one in the region of 0.2 <z. This is presumably because the band gap of the active layer 19 suddenly decreases in the region of 0.1 <z, particularly 0.2 <z, and exhibits metallic properties. Even when antimony was used in place of arsenic or phosphorus, the results were almost the same as in FIG.
[0062]
(Embodiment 5)
FIG. 6 is a cross-sectional view of a semiconductor laser device according to the fifth embodiment of the present invention.
[0063]
In this structure, an n-GaN layer 17 having a thickness of 1 μm and an n-Al layer having a thickness of 0.5 μm are formed on an n-GaN substrate 16. _0.1 Ga _0.9 First cladding layer 22 made of N, active layer 23, p-Al having a thickness of 0.2 μm _0.1 Ga _0.9 A second cladding layer 24 made of N is formed, and n-Al having a thickness of 0.5 μm is formed on the second cladding layer 24. _0.2 Ga _0.8 N _0.99 As _0.01 The current blocking layer 25 is formed, and a stripe-shaped window 26 is formed in the current blocking layer 25, and p-Al having a minimum thickness of 0.7 μm so as to fill the window 26 on the current blocking layer 25. _0.1 Ga _0.9 A third clad layer 27 made of N is formed, and a contact layer 21 made of p-GaN having a thickness of 0.1 μm is further formed thereon. The active layer 23 is made of Al with a thickness of 5 nm. _0.01 Ga _0.97 In _0.02 N _0.99 As _0.01 Barrier layer and 3 nm thick Al _0.01 Ga _0.89 In _0.1 N _0.99 As _0.01 It is a triple quantum well layer comprised by the well layer which consists of. The stripe-shaped window 26 is provided for current confinement, and its width w is 3 μm. The length of the resonator is 1 mm, and the resonator is formed by cleaving the substrate.
[0064]
With this structure, the nitrogen vacancy in the active layer 23 and the current blocking layer 25 can be filled with arsenic, so that the reactive current of the semiconductor laser device can be reduced and a semiconductor laser device with low operating current and high efficiency can be obtained.
[0065]
In the semiconductor laser device according to the fifth embodiment, the effective refractive index in the direction perpendicular to the main surface of the active layer 23 including the window 26 is n1, and the effective refractive index in the direction perpendicular to the main surface of the active layer 23 not including the window 26 is used. When the effective refractive index is n2, the value of n1-n2 = Δn is Δn = 5.75 × 10 ^-3 Met.
[0066]
FIG. 7 shows the result of comparison between the current-light output characteristics of the semiconductor laser device of the present invention according to the fifth embodiment and the current-light output characteristics of the conventional semiconductor laser. In FIG. 7, curve A represents the current-light output characteristic of the semiconductor laser device of the present invention, and curve B represents the current-light output characteristic of the conventional semiconductor laser device. Here, in the conventional semiconductor laser device, the active layer 23 and the current blocking layer 25 do not contain arsenic. That is, the active layer 23 is made of 5 nm thick Al. _0.01 Ga _0.97 In _0.02 Barrier layer made of N and 3 nm thick Al _0.01 Ga _0.89 In _0.1 A triplet well layer composed of a well layer made of N, and the current blocking layer 25 is n-Al _0.2 Ga _0.8 N.
[0067]
FIG. 7 shows that the semiconductor laser device of the present invention has a smaller threshold current and better quantum efficiency than the conventional semiconductor laser device. This is considered to be due to the following three reasons.
[0068]
That is, by providing the current blocking layer 25 having a larger Al composition ratio than the second cladding layer 24 and the third cladding layer 27, that is, a large band gap, light is hardly absorbed in the current blocking layer 25. In addition, it is considered that the reactive current is reduced. In particular, since arsenic is introduced into the current blocking layer 25, there is almost no nitrogen vacancy in the current blocking layer 25, and it is conceivable that light is no longer absorbed in the current blocking layer 25.
[0069]
Further, in the semiconductor laser device of the present invention, since arsenic is introduced into the active layer 23, there is almost no nitrogen vacancy in the active layer 23, and the electric field inside the active layer 23 is relaxed, so that the emission efficiency of the semiconductor laser device is improved. This is considered to be because the operating current is reduced as compared with the conventional semiconductor laser device.
[0070]
When the beam shape of the semiconductor laser device of the present invention was measured, a unimodal beam shape was obtained. This is because the current blocking layer 25 having a larger band gap than the second cladding layer 24 and the third cladding layer 27 is provided, and the effect of light confinement in the window 26 portion is improved by setting n2 <n1. Conceivable.
[0071]
The Al composition ratio of the current block layer 25 is preferably set higher than the Al composition ratio of the third cladding layer 27. When the Al composition ratio of the current blocking layer 25 is the same as or lower than the Al composition ratio of the third cladding layer 27, the value of n1 decreases due to the plasma effect at the time of current injection, resulting in an anti-guide type waveguide mechanism. One transverse mode characteristic may not be obtained.
[0072]
FIG. 8 shows the relationship between the astigmatic difference and the optical output regarding the semiconductor laser device of the present invention according to the fifth embodiment.
[0073]
From FIG. 8, it was found that an astigmatic difference of 1 μm or less was obtained with an optical output of 1 mW or more, and a semiconductor laser device having basic characteristics necessary as a light source for an optical disk system was realized.
[0074]
FIG. 9 shows the relationship between Δn and astigmatic difference regarding the semiconductor laser device of the present invention according to the fifth embodiment. In order to adjust Δn, only the Al composition ratio of the current blocking layer 25, the Al composition ratio and film thickness of the second cladding layer 24, and the Al composition ratio of the third cladding layer 27 are changed. This configuration can be realized by using the same configuration as described above.
[0075]
According to FIG. 9, Δn <3 × 10 ^-3 Since the astigmatic difference becomes larger than 5 μm, Δn is set to 3 × 10 in order to realize the astigmatic difference of 5 μm or less necessary as a light source of the optical disk system. ^-3 I understood that it should be the above.
[0076]
FIG. 10 shows changes in the threshold current when the width of the window 26 is changed using the layer thickness of the second cladding layer 24 as a parameter. Here, the width of the window 26 refers to the minimum width w of the window 26 shown in FIG. In FIG. 10, curves when the thickness of the second cladding layer 24 is 0.1 μm, 0.15 μm, 0.2 μm, and 0.25 μm are represented as C, D, E, and F, respectively.
[0077]
10 that the width of the window 26 that minimizes the threshold current is 1.5 to 2.3 μm when the thickness of the second cladding layer 24 is in the range of 0.1 to 0.25 μm. It was. Note that if the film thickness of the second cladding layer 24 is made too large, the reactive current increases, leading to an increase in threshold current and operating current. Therefore, the film thickness of the second cladding layer 24 may be 0.2 μm or less. .
[0078]
In the fifth embodiment, Δn ≦ 8 × 10 ^-3 If it is. By doing so, it is possible to obtain a semiconductor laser device having a stable transverse mode characteristic by cutting off the higher-order mode and suppressing spatial hole burning particularly during high-power operation.
[0079]
The same effect can be obtained by adjusting Δn by changing the Al composition ratio of the current blocking layer 25, the Al composition ratio of the second cladding layer 24, the Al composition ratio of the third cladding layer 27, and the like. can get.
[0080]
Further, the shape of the current blocking layer 25 in the stripe region may be symmetric with respect to the window 26. If the shape of the current blocking layer 25 is symmetrical with respect to the window 26, stable transverse mode characteristics can be obtained.
[0081]
Although the triple quantum well layer is used in the fifth embodiment, a single quantum well layer, a double quantum well layer, a quadruple or more quantum well layer or a bulk is used instead of the triple quantum well layer. The same effect can be obtained even when an active layer is used.
[0082]
In the fifth embodiment, a semiconductor having a band gap larger than the energy of light having an oscillation wavelength is used as the current blocking layer 25, and 3 × 10 ^-3 ≦ Δn ≦ 8 × 10 ^-3 In this case, the first clad layer 22, the second clad layer 24, the third clad layer 27, or the current blocking layer 25 may be a semiconductor containing only one of Al and Ga, such as GaN and AlN. .
[0083]
In the fifth embodiment, a semiconductor having a band gap larger than the energy of light having an oscillation wavelength is used as the current blocking layer 25, and 3 × 10 ^-3 ≦ Δn ≦ 8 × 10 ^-3 If so, the first clad layer 22, the second clad layer 24, the third clad layer, or the current blocking layer 25 may have a multilayer structure. For example, the first cladding layer 22 is n-Al having a thickness of 0.5 μm from the n-GaN substrate 16 side. _0.1 Ga _0.9 An N layer and an n-GaN layer having a thickness of 60 nm are sequentially stacked, and the second cladding layer 24 is formed from the n-GaN substrate 16 side by a p-GaN layer having a thickness of 60 nm and a p-layer having a thickness of 0.13 μm. -Al _0.1 Ga _0.9 By sequentially stacking the N layer, a separated light confinement structure can be obtained, and the light confinement rate in the direction perpendicular to the active layer 23 can be improved.
[0084]
In this fifth embodiment, arsenic is added to all of the quantum well layers. However, if arsenic is added to at least one layer, the characteristics of the semiconductor laser device can be improved. However, arsenic is preferably added to at least all of the barrier layers of the quantum well layer, and more preferably arsenic is added to all of the quantum well layers.
[0085]
In the fifth embodiment, the active layer 23 does not contain any one or two of Al, Ga, and In, for example, a mixed crystal such as Ga. _0.9 In _0.1 N _0.99 As _0.01 And GaN _0.99 As _0.01 Alternatively, the composition ratio of Al, Ga, and In may be controlled to match the lattice constant with that of the GaN substrate.
[0086]
In the fifth embodiment, phosphorus or antimony may be used instead of arsenic, or any two or more of arsenic, phosphorus and antimony may be used.
[0087]
In the fifth embodiment, all the conductivity types may be reversed.
[0088]
As the current blocking layer 25, a high-resistance semiconductor layer, for example, undoped Al _0.2 Ga _0.8 A layer made of N may be used.
[0089]
(Embodiment 6)
FIG. 11 is a cross-sectional view of a blue light emitting diode device according to a sixth embodiment of the present invention.
[0090]
In this structure, an n-GaN layer 17 having a thickness of 1 μm and an n-Al layer having a thickness of 0.5 μm are formed on an n-GaN substrate 16. _0.1 Ga _0.9 First cladding layer 22 made of N, undoped Al with a thickness of 10 nm _0.01 Ga _0.89 In _0.1 N _0.99 As _0.01 Active layer 28, 10 nm thick undoped Al _0.2 Ga _0.79 In _0.01 N _0.99 As _0.01 Barrier layer 29 made of p-Al having a thickness of 0.5 μm _0.1 Ga _0.9 A second clad layer 30 made of N and a contact layer 21 made of p-GaN having a thickness of 0.1 μm are sequentially formed (this blue light-emitting diode device is hereinafter referred to as sample A).
[0091]
With this structure, a barrier layer 29 having a larger band gap than the active layer 28 is used between the active layer 28 and the second cladding layer 30, so that carriers are diffused from the active layer 28 to the second cladding layer 30. Can be suppressed, and the light emission efficiency of the blue light emitting diode device can be improved. Especially as the barrier layer 29, Al _0.2 Ga _0.79 In _0.01 N _0.99 As _0.01 Therefore, the light emission efficiency of the blue light emitting diode device can be further improved.
[0092]
FIG. 12 shows sample A, Al of the barrier layer 29 _0.2 Ga _0.79 In _0.01 N _0.99 As _0.01 Instead of 10 nm thick Al _0.2 Ga _0.79 In _0.01 It is the figure which compared the luminous efficiency of the blue light emitting diode device when N is used (sample B) and when there is no barrier layer 29 (sample C). In addition, the white circle in FIG. 12 represents the measurement result of the luminous efficiency with respect to each sample.
[0093]
From FIG. 12, the luminous efficiency is increased by using a barrier layer 29 having a larger band gap than the second cladding layer 30 on the second cladding layer 30 side of the active layer 28, and Al containing As _0.2 Ga _0.79 In _0.01 N _0.99 As _0.01 It turned out that luminous efficiency increases further by using a layer.
[0094]
In the sixth embodiment, phosphorus or antimony may be used in place of arsenic contained in the barrier layer 29. Further, any two or more of arsenic, phosphorus and antimony may be used.
[0095]
In the sixth embodiment, the barrier layer 29 is a p-type conductive layer such as p-Al. _0.2 Ga _0.79 In _0.01 N _0.99 As _0.01 The same effect can be obtained even if a layer made of the same is used.
[0096]
Further, in the sixth embodiment, when the conductivity is reversed including the substrate, that is, 0.5 μm thick p-Al formed sequentially on the p-GaN substrate. _0.1 Ga _0.9 First cladding layer made of N and 10 nm thick undoped Al _0.01 Ga _0.89 In _0.1 N _0.99 As _0.01 10 nm thick undoped Al between active layers made of _0.01 Ga _0.89 In _0.1 N _0.99 As _0.01 The same effect can be obtained even in the case where a barrier layer is inserted. The barrier layer described above can also be used in the fifth embodiment shown in FIG.
[0097]
【The invention's effect】
As described above, the semiconductor device of the present invention has one or more elements selected from the group consisting of boron, aluminum, gallium and indium as the semiconductor layer, and 1 selected from the group consisting of phosphorus, arsenic and antimony. By using a compound consisting of two or more elements and nitrogen, and having the total number of atoms of phosphorus, arsenic and antimony smaller than the number of atoms of nitrogen, nitrogen vacancy in the semiconductor layer can be almost eliminated. Reliability can be improved.
[0098]
The semiconductor device of the present invention is selected from the group consisting of one or more elements selected from the group consisting of boron, aluminum, gallium and indium, and the group consisting of phosphorus, arsenic and antimony as the active layer constituting the double heterostructure. Reducing the nitrogen vacancy in the active layer by using a compound comprising one or more elements selected from the group consisting of nitrogen and the total number of atoms of phosphorus, arsenic and antimony being smaller than the number of nitrogen atoms At the same time, the piezo effect in the active layer can be relaxed, the characteristics such as light emission efficiency can be improved, and the reliability can be improved.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a semiconductor device according to a first embodiment of the present invention.
FIG. 2 is a sectional view of the semiconductor laser device according to the second embodiment.
FIG. 3 is a cross-sectional view showing a manufacturing process of the semiconductor laser device according to the second embodiment.
FIG. 4 is a sectional view of a blue light emitting diode device according to the third embodiment;
FIG. 5 is a graph showing the relationship between the arsenic composition ratio z in the active layer and the light emission efficiency for the blue light emitting diode device;
FIG. 6 is a sectional view of the semiconductor laser device according to the fifth embodiment.
FIG. 7 is a diagram showing a comparison of current-light output characteristics of the semiconductor laser device according to the fifth embodiment and a conventional semiconductor laser device.
FIG. 8 is a diagram showing the relationship between the optical output of the semiconductor laser device and the astigmatic difference in the fifth embodiment
FIG. 9 is a diagram showing the relationship between Δn and astigmatism regarding the semiconductor laser device according to the fifth embodiment;
FIG. 10 is a diagram showing a change in threshold current when the width of the stripe region window is changed using the thickness of the second cladding layer as a parameter for the semiconductor laser device according to the fifth embodiment;
FIG. 11 is a sectional view of a light emitting diode according to the sixth embodiment.
FIG. 12 is a diagram showing a comparison of light emission efficiency depending on the conditions of a barrier layer in the blue light emitting diode device according to the sixth embodiment.
FIG. 13 is a sectional view of a conventional semiconductor device.
[Explanation of symbols]
7 Substrate
8 Semiconductor layer
9 Sapphire substrate
10 Buffer layer
11, 15, 21 Contact layer
12, 18, 22 First cladding layer
13, 19, 23, 28 Active layer
14, 20, 24, 30 Second clad layer
16 n-GaN substrate
17 n-GaN layer
25 Current blocking layer
26 windows
27 Third cladding layer
29 Barrier layer

Claims (4)

A double heterostructure formed on the substrate, the double heterostructure comprising a first clad layer, an active layer and a second clad layer formed from the substrate side; and One or more elements selected from the group consisting of boron, aluminum, gallium, and indium, and at least one of the first cladding layer, the active layer, and the second cladding layer; and phosphorus, arsenic, and antimony A nitrogen atom which is formed from a compound consisting of one or more elements selected from the group consisting of and nitrogen, and the total number of atoms of phosphorus, arsenic and antimony contained in the compound is contained in the compound A semiconductor device characterized by being smaller than a number,
Wherein the first clad layer made of a first conductivity type _{Al x1 Ga 1-x1 N (} 0 ≦ x1 ≦ 1), the active layer is _{Al a Ga b In c N 1} -z1 As z1 or Al _a Ga _b At least one layer of In _c N _1-z1 P _z1 (0 ≦ a, b, c ≦ 1, 0 <z1 ≦ 0.2, a + b + c = 1), and the second cladding layer is the first cladding layer. It is made of Al _x2 Ga _1-x2 N (0 ≦ x2 ≦ 1) of the second conductivity type having a conductivity type opposite to that of the conductivity type, and is further emitted from the active layer on the second cladding layer. Al _y Ga _{1 -y} N _{1 -z 2} As _z2 or Al _y Ga _{1 -y} N _{1 -z2} P _z2 (0 _{≦≦ 1} ) having a band gap larger than the energy of light and having the first conductivity type or high resistance. y ≦ 1, 0 <z2 ≦ 0.2), and a stripe-shaped window is formed in the current blocking layer. , The third cladding layer of the second conductivity type _{Al x3 Ga 1-x3 N (} 0 ≦ x3 ≦ 1) is formed on the current blocking layer including a stripe-shaped window, and 0 ≦ X1, A semiconductor device characterized in that a relationship of X2, X3 <y is established. The effective refractive index in the direction perpendicular to the main surface of the active layer including the stripe-shaped window is n1, and the effective refractive index in the direction perpendicular to the main surface of the active layer does not include the stripe-shaped window. 2. The semiconductor device according to claim 1 , wherein a relationship of n2 <n1 and 3 × 10 ⁻³ ≦ n1−n2 ≦ 8 × 10 ⁻³ is established when the effective refractive index is n2. A double heterostructure formed on the substrate, the double heterostructure comprising a first clad layer, an active layer and a second clad layer formed from the substrate side; and One or more elements selected from the group consisting of boron, aluminum, gallium, and indium, and at least one of the first cladding layer, the active layer, and the second cladding layer; and phosphorus, arsenic, and antimony A nitrogen atom which is formed from a compound consisting of one or more elements selected from the group consisting of and nitrogen, and the total number of atoms of phosphorus, arsenic and antimony contained in the compound is contained in the compound Smaller than number
A semiconductor device characterized by:
Wherein the first clad layer made of a first conductivity type _{Al x1 Ga 1-x1 N (} 0 ≦ x1 ≦ 1), the active layer is _{Al a Ga b In c N 1} -z As z , or Al _a Ga _b Including at least one layer of In _c N _1-z P _z (0 ≦ a, b, c ≦ 1, 0 <z ≦ 0.2, a + b + c = 1), and the second cladding layer includes A second conductivity type Al _x2 Ga _1-x2 N (0 ≦ x2 ≦ 1) having a conductivity type opposite to the first conductivity type ,
The second conductivity type is p-type, and a barrier layer having a larger band gap than the second cladding layer is inserted between the active layer and the second cladding layer;
The barrier layer is Al _a1 Ga _b1 In _c1 N _{1 -z1} As _z1 or Al _a1 Ga _b1 In _c1 N _{1 -z1} P _z1 (0 ≦ a1, b1, c1 ≦ 1, 0 <z1 ≦ 0.2, a1 + b1 + c1 = A semiconductor device comprising 1). A double heterostructure formed on the substrate, the double heterostructure comprising a first clad layer, an active layer and a second clad layer formed from the substrate side; and One or more elements selected from the group consisting of boron, aluminum, gallium, and indium, and at least one of the first cladding layer, the active layer, and the second cladding layer; and phosphorus, arsenic, and antimony A nitrogen atom which is formed from a compound consisting of one or more elements selected from the group consisting of and nitrogen, and the total number of atoms of phosphorus, arsenic and antimony contained in the compound is contained in the compound A semiconductor device characterized by being smaller than a number,
Wherein the first clad layer made of a first conductivity type _{Al x1 Ga 1-x1 N (} 0 ≦ x1 ≦ 1), the active layer is _{Al a Ga b In c N 1} -z As z , or Al _a Ga _b Including at least one layer of In _c N _1-z P _z (0 ≦ a, b, c ≦ 1, 0 <z ≦ 0.2, a + b + c = 1), and the second cladding layer includes A second conductivity type Al _x2 Ga _1-x2 N (0 ≦ x2 ≦ 1) having a conductivity type opposite to the first conductivity type ,
The first conductivity type is p-type, and a barrier layer having a larger band gap than the first cladding layer is inserted between the active layer and the first cladding layer;
The barrier layer is Al _a1 Ga _b1 In _c1 N _{1 -z1} As _z1 or Al _a1 Ga _b1 In _c1 N _{1 -z1} P _z1 (0 ≦ a1, b1, c1 ≦ 1, 0 <z1 ≦ 0.2, a1 + b1 + c1 = A semiconductor device comprising 1).

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