JPH06310815A - Semiconductor device - Google Patents

Abstract

PURPOSE:To contrive the improvement of the voltage-current characteristics of a p-n junction, wherein discontinuities respectively exist in valence bands in the junction interface. CONSTITUTION:A multiple quantum well layer 9 consisting of p-type ZnTe layers and p-type ZnSe layers, respectively used as quantum well layers and barrier layers is formed in a depletion layer on the side of a p-type ZnSe contact layer 5 in the junction part between the layer 5 and a p-type ZnTe contact layer 6. The thickness of each quantum well layer of the layer 9 is determined in such a way that the quantum level of each quantum well layer becomes roughly equal with an energy level on the top of the valence band of each p-type ZnSe layer and each p-type ZnTe layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device,
In particular, it is suitable for application to a light emitting element and other semiconductor devices using II-VI group compound semiconductors.

[0002]

2. Description of the Related Art In recent years, in order to improve the recording density of optical discs and the resolution of laser printers, there is an increasing demand for semiconductor lasers capable of emitting light at short wavelengths, and research aimed at realizing them has been made. It is active.

As a result of earnest studies to meet such demands, the present applicant has used blue light or green light using ZnMgSSe type compound semiconductor, which is one of II-VI group compound semiconductors, as a material for the cladding layer. Proposed a semiconductor laser capable of (for example, Japanese Patent Application No. 4-22935).
No. 6). In this semiconductor laser, n-type GaAs
A laser structure composed of an n-type ZnMgSSe clad layer, an active layer and a p-type ZnMgSSe clad layer is formed on the substrate, and a p-type ZnMgSSe clad layer is formed on the laser structure.
A type ZnSe contact layer is formed. A p-side electrode is formed on the p-type ZnSe contact layer, and an n-side electrode is formed on the back surface of the n-type GaAs substrate.

[0004]

However, in the semiconductor laser using the above II-VI group compound semiconductor, the contact resistance of the p-side electrode with respect to the p-type ZnSe contact layer is high, and good ohmic contact can be obtained. There is a problem that there is no. This is because the carrier concentration obtained by doping p-type impurities into ZnSe is as low as about 10 ¹⁷ cm ^-3 at the maximum, and an electrode capable of obtaining good ohmic contact with p-type ZnSe. The reason is that the material is not found at present.

Regarding the above-mentioned doping of p-type impurities into ZnSe, from the result of measurement by the secondary ion mass spectrometry (SIMS) method, the p-type impurities themselves are 10 ¹⁸ -1.
It is possible to dope up to about 0 ¹⁹ cm ⁻³ , but by deepening the impurity level determined by the doping concentration of the p-type impurity, only a part of the doped p-type impurity is activated and effective carriers are supplied. Since it only functions as an acceptor, it can only obtain a low carrier concentration as described above. FIG. 4 shows such a situation. Even if the doping concentration [N] of N as a p-type impurity is increased, the effective carrier concentration, that is, N _A -N _D (where N _A is the acceptor concentration, N _D
It can be seen that is saturated at a donor concentration of about 4 × 10 ¹⁷ cm ⁻³ .

Therefore, in order to solve the above-mentioned problem, in Japanese Patent Application No. 4-229356, it is possible to dope the ZnTe with an acceptor up to a concentration of about 10 ¹⁹ cm ^-3 , such as Au. Paying attention to the fact that a good ohmic contact can be obtained using the metal of
Also disclosed is a technique for reducing the contact resistance of the p-side electrode by forming a p-type ZnTe contact layer on the p-type ZnSe contact layer and forming a p-side electrode on the p-type ZnTe contact layer. .

However, as shown in FIG. 5, p-type Z
At the interface of the junction between nSe and p-type ZnTe, there is a band discontinuity of about 0.5 eV in the valence band. Then, the valence band of p-type ZnSe is bent downward toward p-type ZnTe, and the change in the valence band convex downward is injected from the p-side electrode into this p-type ZnSe / p-type ZnTe junction. Functioning as a potential barrier for positive holes. Therefore, even if the p-side electrode is formed on the p-type ZnTe contact layer as described above, a good ohmic contact cannot be obtained, and thus a good voltage-current characteristic is not obtained. In FIG. 5, p-type ZnSe and p-type ZnTe are used.
The Fermi level of is approximated to coincide with the top of the valence band.

Therefore, an object of the present invention is to provide the first p-type I having band discontinuity in the valence band at the junction interface.
An object of the present invention is to provide a semiconductor device capable of improving the voltage-current characteristics of the junction between the I-VI group compound semiconductor and the second p-type II-VI group compound semiconductor.

[0009]

In order to achieve the above object, the present invention provides a first p-type II-VI compound semiconductor (5) and a second p-type II-VI compound semiconductor ( 6), and the energy at the top of the valence band of the first p-type II-VI compound semiconductor (5) at the interface of the junction is the second p-type II-VI compound semiconductor (5). 6) In the semiconductor device having energy lower than the top of the valence band, the impurity concentration of the portion of the first p-type II-VI compound semiconductor (5) near the interface is the same as that of the other portion. And a quantum well made of a second p-type II-VI compound semiconductor in the depletion layer of the junction formed on the side of the first p-type II-VI compound semiconductor (5). Layer and first p-type II-VI compound semiconductor Multiple quantum well layer having a layer (9) is provided, the thickness of each quantum well layer quantum level of each quantum well layer first p-type II-VI
The group compound semiconductor (5) and the second p-type II-VI compound semiconductor (6) are set to have energy substantially equal to the top energy of the valence band.

In a preferred embodiment of the semiconductor device according to the present invention, the impurity concentration of the portion of the first p-type II-VI compound semiconductor near the interface of the junction is continuous toward the interface. Is set to increase.

In a preferred embodiment of the semiconductor device according to the present invention, the first p-type II-VI compound semiconductor is p-type ZnSe and the second p-type II-VI compound semiconductor is p-type. Type ZnTe, the impurity concentration of a portion of the p-type ZnSe near the interface of the junction between p-type ZnSe and p-type ZnTe is higher than the impurity concentration of other portions, and at the p-type ZnSe side A multiple quantum well layer having a quantum well layer made of p-type ZnTe and a barrier layer made of p-type ZnSe is provided in the depletion layer of the formed junction, and the thickness of each quantum well layer is equal to that of each quantum well layer. The quantum level is set to be substantially equal to the energy at the top of the valence band of p-type ZnSe and p-type ZnTe.

In a preferred embodiment of the semiconductor device according to the present invention, p in the first p-type II-VI compound semiconductor and the second p-type II-VI compound semiconductor is used.
As the type impurity, N, which is an impurity forming a deep level by high-concentration doping, is used.

In a typical embodiment of the semiconductor device according to the present invention, the semiconductor device is a light emitting element such as a semiconductor laser or a light emitting diode.

[0014]

According to the semiconductor device of the present invention configured as described above, the impurity concentration of the portion of the first p-type II-VI compound semiconductor in the vicinity of the interface of the junction is the same as that of the other portion. Because it is higher than the concentration,
The width of the depletion layer of the junction formed on the p-type II-VI group compound semiconductor side can be reduced. Therefore, holes can easily pass through the junction due to the tunnel effect or the like, so that the amount of current flowing through the junction can be increased.

Further, the second p-type I is formed in the depletion layer of the junction formed on the side of the first p-type II-VI compound semiconductor.
Quantum well layer made of group I-VI compound semiconductor and first
A multi-quantum well layer having a barrier layer made of a p-type II-VI compound semiconductor is provided, and the thickness of each quantum well layer is such that the quantum level of each quantum well layer is the first p-type II. -Group VI compound semiconductor and second p-type II-
Since the energy is set to be almost equal to the energy at the top of the valence band of the Group VI compound semiconductor, holes can easily pass through the junction due to the resonance tunnel effect via these quantum levels.

As described above, the potential barrier due to the band discontinuity of the valence band at the interface of the junction between the first p-type II-VI group compound semiconductor and the second p-type II-VI group compound semiconductor is effective. Therefore, good voltage-current characteristics can be obtained. When the semiconductor device is a light emitting element using a pn junction such as a semiconductor laser or a light emitting diode, the rising voltage of the pn junction can be reduced.

Particularly, when the first p-type II-VI group compound semiconductor is p-type ZnSe and the second p-type II-VI group compound semiconductor is p-type ZnTe, that is, p-type ZnSe and p-type ZnSe. In a semiconductor device having a junction with n-type ZnTe, by forming a p-side electrode on p-type ZnTe, good ohmic contact can be obtained, and thus good voltage-current characteristics can be obtained. .

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a semiconductor laser according to an embodiment of the present invention.

As shown in FIG. 1, in the semiconductor laser according to this embodiment, for example, Si is used as an n-type impurity.
N-type Ga doped with, for example, a (100) plane orientation
On the As substrate 1, for example, an n-type ZnMgSSe cladding layer 2 doped with Cl as an n-type impurity, an active layer 3, a p-type ZnMgSSe cladding layer 4 doped with N as a p-type impurity, for example N as a p-type impurity. -Doped ZnSe contact layer 5 and p-type Z doped with N as a p-type impurity, for example
The nTe contact layer 6 is sequentially stacked. And
On the p-type ZnTe contact layer 7, for example Au or Au / P
A p-side electrode 7 made of d is formed, and an n-side electrode 8 made of, for example, In is formed on the back surface of the n-type GaAs substrate 1.
Are formed. Reference numeral 9 indicates p at the junction between the p-type ZnSe contact layer 5 and the p-type ZnTe contact layer 6.
P-type ZnTe / ZnSe multiple quantum well (MQ) formed in the depletion layer formed on the side of the ZnSe contact layer 5 side.
The W) layer is shown, which will be described in detail later.

In this embodiment, the profile of the N doping concentration [N] in the portion extending from the p-type ZnSe contact layer 5 to the p-type ZnTe contact layer 6 is shown in FIG.
As shown in. That is, as shown in FIG. 2, the doping concentration [N] of N in the p-type ZnSe contact layer 5 depends on the p-type ZnSe contact layer 5 and the p-type ZnT contact layer 5.
A predetermined distance (p-type Z
At the junction between the nSe contact layer 5 and the p-type ZnTe contact layer 6, the width is constant up to a portion apart from the depletion layer formed on the p-type ZnSe contact layer 5 side). [N] in this portion is selected to a value at which the effective carrier concentration is saturated, that is, about 4 × 10 ¹⁷ cm ⁻³ (see FIG. 4). On the other hand, of the p-type ZnSe contact layer 5, the p-type ZnSe contact layer 5 and the p-type Z
[N] in the portion within the above-described predetermined distance from the interface of the junction with the nTe contact layer 6 continuously increases toward the interface of the junction. Then, [N] increases stepwise at the interface of the junction, and [N] in the p-type ZnTe contact layer 6 has this value. [N] in the p-type ZnTe contact layer 6 is selected to be a value sufficiently higher than [N] in the p-type ZnSe contact layer 5, for example, about 2 × 10 ¹⁸ cm ⁻³ (see FIG. 4). . For this value of [N], p
The carrier concentration in the ZnTe contact layer 6 is unsaturated.

In this case, of the p-type ZnSe contact layer 5, this p-type ZnSe contact layer 5 and p-type ZnTe are used.
The value of [N] in the portion within the predetermined distance from the interface of the junction with the contact layer 6 exceeds the value at which the carrier concentration is saturated, and the impurity level of N is deepened, but is trapped at this deep level. The holes can be made to fall to the p-type ZnTe contact layer 6 side. Therefore, it is possible to reduce the width of the depletion layer on the p-type ZnSe contact layer 5 side and increase [N] in the p-type ZnTe contact layer 6 by modulation doping of N as shown in FIG. As a result, it is possible to increase the amount of current that can be passed through the semiconductor laser.

Here, the p-type ZnSe contact layer 5 and p
P-type Zn at the junction with the Zn-type ZnTe contact layer 6
The calculation example of the width of the depletion layer formed on the Se contact layer 5 side is as follows.

As described above, the carrier concentration in the p-type ZnSe contact layer 5 is about 5 × 10 ¹⁷ cm ^-3 , p
Type ZnTe contact layer 6 has a carrier concentration of 10 ¹⁹ c
It can be about m ^-3 . On the other hand, the valence band at the interface of the junction between the p-type ZnSe contact layer 5 and the p-type ZnTe contact layer 6 has a band discontinuity of about 0.5 eV (see FIG. 5). Such p-type Zn
The valence band of the junction between the Se contact layer 5 and the p-type ZnTe contact layer 6, the junction is assumed to be a step junction, the p-type ZnSe contact layer 5 side _{W = (2εφ T / qN A} ) 1/2 Band bending occurs over the width of (1). Here, q is the absolute value of electron charge, ε is the dielectric constant of ZnSe, and φ _T is p.
This represents the size of discontinuity of the valence band (about 0.5 eV) at the interface of the junction between the n-type ZnSe contact layer 5 and the p-type ZnTe contact layer 6.

Now, the acceptor concentration N _{A of} the p-type ZnSe contact layer 5 except for the high-concentration doped portion near the junction interface is 5 × 10 ¹⁷ cm ⁻³ , and the acceptor concentration N of the high-concentration doped portion is Assuming that _A is 1 × 10 ¹⁸ cm ⁻³ which is twice the average value, and W in this case is calculated using the equation (1), W = 23 nm. On the other hand, W is about 32 nm when the high-concentration doping part is not provided in the part of the p-type ZnSe contact layer 5 near the interface of the junction. That is, p-type ZnSe
Since the high-concentration doped portion is provided in the contact layer 5 in the vicinity of the interface of the junction, the width W of the depletion layer is reduced by about 9 nm as compared with the case where the high-concentration doped portion is not provided. ing. Since the width W of the depletion layer is thus reduced, p-type ZnSe
Holes easily pass through the junction between the contact layer 5 and the p-type ZnTe contact layer 6 due to the tunnel effect.

On the other hand, as described above, in this embodiment, the p-type ZnSe contact layer 5 and the p-type ZnT are used.
In the depletion layer formed on the p-type ZnSe contact layer 5 side at the junction with the e-contact layer 6, a quantum well layer made of p-type ZnTe and a barrier layer made of p-type ZnSe are alternately stacked. Type ZnTe / ZnSe MQW layer 9
Is provided. This p-type ZnTe / ZnSe MQW
The layer 9 has a quantum well layer made of p-type ZnTe interposed in a depletion layer formed on the p-type ZnSe contact layer 5 side at a junction between the p-type ZnSe contact layer 5 and the p-type ZnTe contact layer 6. It can also be said that it was formed by. In this case, the thickness L _B of the barrier layer made of p-type ZnSe is constant, but the thickness L _W of the quantum well layer made of p-type ZnTe is the same as that of the p-type ZnSe contact layer 5.
To the p-type ZnTe contact layer 6, the thickness gradually increases. Specifically, the thickness L _W of the quantum well layer made of p-type ZnTe is set as follows.

First, with respect to the width L _{W of a} quantum well made of p-type ZnTe in a single quantum well having a structure in which both sides of a quantum well layer made of p-type ZnTe are sandwiched by barrier layers made of p-type ZnSe, the first quantum is formed. How the level E ₁ changes was obtained by quantum mechanical calculation for a well potential of a finite barrier. However, in this calculation, p-type ZnSe is used as the mass of electrons in the quantum well layer and the barrier layer.
And 0.6 m ₀ (m ₀ : static mass of electron) was used assuming the effective mass m _{h of} holes in p-type ZnTe, and the depth of the well was 0.5 eV. From this calculation result, p-type Z
It can be seen that the first quantum level E ₁ formed in the quantum well can be lowered by reducing the width L _{W of the} quantum well made of nTe. Therefore, in this embodiment, this is utilized to change the thickness L _W of the quantum well layer made of p-type ZnTe.

That is, from the junction interface between the p-type ZnSe contact layer 5 and the p-type ZnTe contact layer 6, the p-type Z
The band bending occurring over the width W on the nSe contact layer 5 side is given by a quadratic function φ (x) = φ _T {1- (x / W)} ² (2) of the distance x from the interface of this junction. . Therefore, p-type ZnTe / ZnSeMQW
The design of the layer 9 is based on the equation (2): the first quantum level E formed in each of the quantum well layers made of p-type ZnTe.
_This can be done by changing L _W such that 1 is almost equal to the energy at the top of the valence band of p-type ZnSe and p-type ZnTe, and is almost equal to each other. In practice, this agreement is the thermal energy ~ kT
There is no problem as long as they match within a range of (k: Boltzmann's constant, T: absolute temperature).

In FIG. 3, the width L _{B of the} barrier layer made of p-type ZnSe in the p-type ZnTe / ZnSe MQW layer 9 is 2n.
An example of designing the quantum well width L _W when m is shown. However, the acceptor concentration N in the p-type ZnSe contact layer 5 is N.
_A is set to 5 × 10 ¹⁷ cm ⁻³ . In addition, p-type ZnTe
Doping concentration [N] gradually toward the contact layer 6
To increase the average doping concentration [N] in the p-type ZnTe / ZnSe MQW layer 9 to 1 × 10 ¹⁸ cm ⁻³ . Further, the acceptor concentration N _A in the p-type ZnTe contact layer 6 is set to 1 × 10 ¹⁹ cm ⁻³ . As shown in FIG. 3, in this case, there are five quantum well widths L in total.
Let _W be a p-type ZnS so that its first quantum level E ₁ matches the Fermi level of p-type ZnSe and p-type ZnTe.
From the e-contact layer 5 toward the p-type ZnTe contact layer 6, L _W = 0.3 nm, 0.4 nm, 0.6 nm,
It is changed to 0.9 nm and 1.6 nm.

As described above, the p-type ZnSe contact layer 5 is formed.
Since the p-type ZnTe / ZnSe MQW layer 9 is provided in the depletion layer formed on the p-type ZnSe contact layer 5 side at the junction between the p-type ZnTe contact layer 6 and the p-type ZnTe contact layer 6, the p-type ZnTe / ZnSe MQW layer 9 is formed. Of the p-type ZnSe contact layer 5 and the p-type ZnT by the resonant tunneling effect via the first quantum level E ₁ of each quantum well of
The potential barrier between the e-contact layer 6 and the e-contact layer 6 is effectively eliminated, so that the p-type ZnSe contact layer 5 and the p-type Z
Holes can easily flow through the junction with the nTe contact layer 6.

Next, a method of manufacturing the semiconductor laser according to this embodiment constructed as described above will be described.

As shown in FIG. 1, first, an n-type ZnMgSSe clad layer 2, an active layer 3, a p-type ZnMgSSe clad layer 4, and a p-type are formed on an n-type GaAs substrate 1 by, for example, a molecular beam epitaxy (MBE) method. ZnSe contact layer 5, p-type ZnTe / ZnSe MQW layer 9 and p-type Z
The nTe contact layer 6 is sequentially epitaxially grown. Here, the formation of the p-type ZnTe / ZnSe MQW layer 9 can be easily performed only by opening and closing the shutter of the molecular beam in the MBE device.

In this epitaxial growth by the MBE method, for example, a Zn raw material has a purity of 99.999.
9% Zn is used, Mg with a purity of 99.9% is used as the Mg raw material, and 99.9999% ZnS is used as the S raw material.
Is used as the Se raw material, and Se having a purity of 99.9999%
To use. In addition, n of the n-type ZnMgSSe cladding layer 2 is
The doping of Cl as a type impurity has a purity of 99.
Using 999% ZnCl ₂ as a dopant, the p-type ZnMgSSe cladding layer 4, the p-type ZnSe contact layer 5, the p-type ZnTe / ZnSe MQW layer 9 and the p-type ZnTe contact layer 6 are N-type as p-type impurities.
For example, doping of electron cyclotron resonance (EC
It is performed by irradiating with N ₂ plasma generated by a plasma gun using R).

In this case, the p-type ZnSe contact layer 5,
p-type ZnTe / ZnSe MQW layer 9 and p-type ZnTe
At the time of doping the contact layer 6 with N, in order to obtain the profile of the doping concentration [N] as shown in FIG. 2, the plasma gun is formed along the profile of [N] as shown by the broken line in FIG. Change the input power of. In p-type impurity doping using this plasma gun, the doping amount and the deep level in the vicinity of the interface of the junction between the p-type ZnSe contact layer 5 and the p-type ZnTe contact layer 6 can be controlled relatively easily. Is.

After that, the p-side electrode 7 is formed on the p-type ZnTe contact layer 6, and the n-side electrode 8 is formed on the back surface of the n-type GaAs substrate 1 to complete the intended semiconductor laser.

As described above, according to the semiconductor laser of this embodiment, the p-type ZnSe contact layer 5 is provided with the p-type ZnSe contact layer 5 and the p-type ZnTe contact layer 6 in the vicinity of the interface. Since the doping concentration [N] of N in the portion is higher than that in the other portions, the width of the depletion layer formed on the p-type ZnSe contact layer 5 side can be reduced in this junction portion. Holes can easily pass through this junction due to the tunnel effect. Further, p-type ZnTe / ZnS is formed in the depletion layer formed on the p-type ZnSe contact layer 5 side at this junction.
By providing the eMQW layer 9, the potential barrier in this junction can be effectively eliminated.

As described above, a semiconductor laser capable of emitting blue or green light having excellent voltage-current characteristics can be realized.

Although one embodiment of the present invention has been specifically described above, the present invention is not limited to the above embodiment, and various modifications can be made based on the technical idea of the present invention. .

For example, although the case where the present invention is applied to the semiconductor laser has been described in the above-mentioned one embodiment, the present invention can also be applied to the light emitting diode, and more generally, the bonding interface. It is possible to apply to various semiconductor devices having a pp junction in which band discontinuity exists in the valence band.

[0039]

As described above, according to the semiconductor device of the present invention, the first p-type II-VI group compound semiconductor having the band discontinuity in the valence band at the junction interface and the second p-type compound semiconductor. The voltage-current characteristics of the junction with the type II-VI compound semiconductor can be improved.

[Brief description of drawings]

FIG. 1 is a sectional view showing a semiconductor laser according to an embodiment of the present invention.

FIG. 2 is a graph showing an example of a profile of N doping concentration [N] in a portion extending from the p-type ZnSe contact layer to the p-type ZnTe contact layer in the semiconductor laser according to the embodiment of the present invention.

FIG. 3 is an energy band diagram of a portion extending from the p-type ZnSe contact layer to the p-type ZnTe contact layer in the semiconductor laser according to the embodiment of the present invention.

FIG. 4 is a graph showing the relationship between the effective carrier concentration in ZnSe and the N doping concentration in ZnSe.

FIG. 5 is an energy band diagram of a p-type ZnSe / p-type ZnTe junction.

[Explanation of symbols]

 1 n-type GaAs substrate 2 n-type ZnMgSSe clad layer 3 active layer 4 p-type ZnMgSSe clad layer 5 p-type ZnSe contact layer 6 p-type ZnTe contact layer 7 p-side electrode 8 n-side electrode 9 p-type ZnTe / ZnSeMQW layer

Claims (5)

[Claims] 1. A junction between a first p-type II-VI compound semiconductor and a second p-type II-VI compound semiconductor, the first p-type II being present at an interface of the junction. -V
In the semiconductor device, the energy at the top of the valence band of the group I compound semiconductor is lower than the energy at the top of the valence band of the second p-type II-VI compound semiconductor. The impurity concentration of a portion of the group VI compound semiconductor in the vicinity of the interface is higher than that of other portions, and the impurity is formed on the side of the first p-type II-VI compound semiconductor. The second p-type II-VI is formed in the depletion layer of the junction.
Of a quantum well layer made of a group compound semiconductor and the first p
A multiple quantum well layer having a barrier layer made of a type II-VI compound semiconductor, the thickness of each quantum well layer is such that the quantum level of each quantum well layer is the first p-type. A semiconductor device, wherein the energy is set to be substantially equal to the energy at the top of the valence band of the II-VI group compound semiconductor and the second p-type II-VI group compound semiconductor. 2. The semiconductor device according to claim 1, wherein the impurity concentration continuously increases toward the interface. 3. The first p-type II-VI group compound semiconductor is p-type ZnSe, and the second p-type II-V compound semiconductor.
The group I compound semiconductor is p-type ZnTe, and the impurity concentration of a portion of the p-type ZnSe near the interface of the junction between the p-type ZnSe and the p-type ZnTe is higher than the impurity concentration of other portions. In addition, in the depletion layer of the junction formed on the p-type ZnSe side, the quantum well layer made of the p-type ZnTe and the p-type Z
A multiple quantum well layer having a barrier layer made of nSe is provided, and the thickness of each quantum well layer is such that the quantum level of each quantum well layer is the p-type ZnSe and the p-type ZnSe.
3. The semiconductor device according to claim 1, wherein the energy is set to be substantially equal to the energy at the top of the valence band of ZnTe type. 4. The semiconductor device according to claim 1, wherein the impurity is N. 5. The semiconductor device according to claim 1, wherein the semiconductor device is a light emitting element.