JPH0783140B2 - Group 2-6 compound semiconductor p-type electrode structure - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device having a p-type 2-6 group compound semiconductor layer, and more particularly to a blue light emitting element, a light emitting diode and a semiconductor laser.

[0002]

2. Description of the Related Art As examples of conventional 2-6 group compound semiconductor devices, JP-A-1-296687 and JP-A-62-8 are known.
Although there are 8329, JP 61-46031, and JP 62-172766, a semiconductor device having a good electrode structure has not been realized.

Further, sulfur (S) or selenium (Se)
2-6 group compound semiconductor material containing (ZnSe, ZnS,
ZnSSe, ZnCdSSe, etc.) have a large forbidden band width and are used as materials for blue light emitting devices. The p electrode for injecting holes has a structure in which Au is vapor-deposited on p-type ZnSe. For example, Applied Physics Letters [Applied Physics Letter]
s] Vol. 59, para. 1272, 1991.

[0004]

However, since the energy position of the valence band edge of the 2-6 group compound semiconductor material containing sulfur or selenium is much lower than the Fermi level of the metal, the Schottky property of such a structure is not improved. There is a problem that it becomes an electrode and has a large resistance and a high rising voltage.

An object of the present invention is to reduce the resistance of an electrode of a p-type 2-6 group compound semiconductor.

[0006]

The p-type electrode structure of the present invention comprises a p-type 2-containing sulfur (S) or selenium (Se).
In a semiconductor device having a p-type 2-6 semiconductor layer made of a Group 6 compound semiconductor material, adjacent to the p-type 2-6 semiconductor layer, the lattice length is equal to or different from the critical thickness p-type _{In x Ga y Al z P (} x + y + z
= 1, 0 ≦ x <1, 0 ≦ y ≦ 1, 0 ≦ z ≦ 1) p-type 3-5 semiconductor layer made of semiconductor or superlattice,
A p-electrode is provided directly on the type 3-5 semiconductor layer or via a second p-type 3-5 semiconductor layer, and the energy position of the valence band edge of the p-type 3-5 semiconductor layer is at the p-electrode part. High, and decreases continuously or stepwise as it approaches the p-type 2-6 semiconductor layer, wherein the second p-type 3-5 semiconductor layer is a valence band edge of the p-type 3-5 semiconductor layer. The p-type 3-5 group compound semiconductor layer has one or more higher valence band edges than the energy position of 1.

[0007]

The energy position of the valence band edge of the 2-6 group compound semiconductor material containing sulfur or selenium is lower than the Fermi level of metal by 1 eV or more. Therefore, when holes are injected into the 2-6 semiconductor, 1 eV is applied to the hetero interface.
The above barrier exists, the resistance is large, and the rising voltage is 20 V or more. In addition, when a p-type 2-6 semiconductor layer is formed on p-type GaAs widely used as a semiconductor substrate and holes are to be injected from the GaAs layer, the energy at the valence band edge of the 2-6 semiconductor and GaAs is also reduced. There is a barrier of about 1 eV due to the difference in position, the resistance is large, and the rising voltage is 20 V or more.

The energy position of the valence band edge of the InGaAlP mixed crystal semiconductor is between the Fermi level of the metal and the valence band edge of the Group 2-6 compound semiconductor containing sulfur or selenium. By controlling the composition of the InGaAlP semiconductor, the position of the valence band edge can be made substantially equal to the Fermi level of the metal at the interface with the metal, and can be lowered as it approaches the 2-6 semiconductor layer. The barrier at the interface with the 2-6 semiconductor is greatly reduced, and holes are easily injected. Also, I
In the nGaAlP mixed crystal, the position of the valence band edge can be changed without changing the lattice length by changing the composition of Ga and Al, which is easy to manufacture.

[0009]

【Example】

(Embodiment 1) The present invention will be described with reference to the drawings.
FIG. 1 is a sectional view showing an embodiment of the first invention.

[0010] ZnS ₀ that Cl was added on the substrate 10 made of n-type _{GaAs. 0 7 Se 0. 9} 3 n -type 2-6 consisting
Semiconductor layer 11 (thickness 1 μm, n = 1 × 10 ¹⁸ c
m ^{_-.. 3)} and N ZnS ₀ was added _{0 7} Se _{0 9 3} p-type 2-6 semiconductor layer 12 made of (thickness 1 [mu] m, p = 5x1
^{_{0 1 7 cm -.. 3}} ) was grown by molecular beam epitaxy (MBE) method, an In ₀ addition of Zn ₅ Al _{0 5} P
(Thickness 100 nm, p = ¹ × 10 ¹⁸ cm ⁻³ ) and In
_{0. 5 Ga 0. 5 P} ( thickness 100nm, p = 1 × 10
^The p-type 3-5 semiconductor layer 13 made of ¹⁹ cm ⁻³ ) is grown by the gas source MBE method, and the p-electrode 14 made of AuZn (thickness 300 nm) and the n-electrode 15 made of AuGeNi (thickness 300 nm) are vacuum-deposited. After being formed by the method, a light emitting diode was manufactured by heating at 300 ° C. for 10 minutes. p-type 2-6 semiconductor layer 12 and p-type 3-5 semiconductor layer 1
The lattice lengths of 3 were equal, and a good semiconductor layer having no lattice defect was formed.

By introducing the p-type 3-5 semiconductor layer 13, p-
The applied voltage required to pass a current in the forward direction of the n-junction is 5V
It was low, and good emission characteristics were obtained. This is because the barriers at the interface between the p-type 2-6 semiconductor layer 12 and the p-type 3-5 semiconductor layer 13 and the interface between the p-type 3-5 semiconductor layer 13 and the p-electrode 14 became smaller.

[0012] While using the same material for the p-type 2-6 semiconductor layer and the grating length as p-type 3-5 semiconductor layer in the above-described embodiment is not limited thereto, Be added _{In 0. 3 Ga 0. 7} P
(Thickness 5 nm, p = 1 × 10 ¹⁹ cm ⁻³ ) such as InGa having a lattice length equal to or less than the critical film thickness different from that of the p-type 2-6 semiconductor layer.
An AlP mixed crystal may be used.

(Embodiment 2) FIG. 2 is a sectional view showing an embodiment of the second invention.

[0014] n-type _{In 0. 0 4 Ga 0.} 9 6 on the substrate 20 made of As, n-type 2 consisting of Cl added the ZnSe
-6 semiconductor layer 21 (thickness 1 μm, n = 1 × 10 ¹⁸ cm
^{_-.. 3)} and Zn _{0 8} Cd ₀ consisting ₂ Se active layer 22
(Thickness 10 nm), p-type 2 consisting of N-doped ZnSe
-6 semiconductor layer 23 (thickness 1 μm, p = 5 × 10 ¹⁷ cm
^-3 ) was grown by the molecular beam epitaxy (MBE) method and Be-added In _0.54 Al _0.46 P / In
_{0. 5 4} Ga _{0 a. 4 6} P p-type 3-5 semiconductor layer 24 made of super lattice grown by gas source MBE, AuZn
P-electrode 25 (thickness 300 nm) made of AuGeNi
An n-electrode 26 (thickness: 300 nm) composed of was formed by a vacuum vapor deposition method to produce a light emitting diode. The superlattice structure of the p-type 3-5 semiconductor layer 24 is In _0.54 Al _0.46
A thickness of P layer is 3nm constant, In _{0. 5 4} Ga
_0.4 thickness of ₆ P layer is 0.5nm at the interface between the p-type 2-6 semiconductor layer 23, and wider 0.5nm increments in each cycle as the proximal get to the p-electrode 25, the p-electrode It is 20 nm at the interface with 25.

The applied voltage required to pass a current in the forward direction of the pn junction was as low as 4 V, and strong blue light emission was obtained. This is because the valence band edge of the p-type 3-5 semiconductor layer 24 continuously changes and becomes lower as it approaches the p-type 2-6 semiconductor layer 23, and holes are easily injected. is there.

In the above-mentioned embodiment, the p-type 3-5 semiconductor layer is made of a material having the same lattice length as that of the p-type 2-6 semiconductor layer. However, the material is not limited to this, and In 0.5 Al doped with Be can be used <sub>.
0. 5 P / In 0.</sub> 5 8 Ga 0. 4 2 P strained superlattice such as a grating length is below the critical thickness which is different from the p-type 2-6 semiconductor layer In
A GaAlP superlattice may be used.

(Embodiment 3) FIG. 3 is a sectional view showing an embodiment of the third invention.

Second p-type 3-5 made of p-type GaAs substrate
On the semiconductor layer 30 (thickness 350 .mu.m), In0 was added _{Be. 5 Ga 0. 5 P} ( thickness 100nm, p = 1 × 1
^{_{0 19 cm -.. 3)}} , In 0 5 Ga 0 2 5 Al
_{0. 2 5} P (thickness ^{100nm, p = 1 × 10 1} 8 cm
^{_{-.. 3), In 0}} 5 Al 0 5 P ( thickness 100 nm, p
= 1 × 10 ¹⁸ cm ⁻³ ), the p-type 3-5 semiconductor layer 31 is grown by the gas source MBE method, and then the p-type 2-6 semiconductor layer 32 (thickness: 2) made of N-doped ZnSe.
μm, p = 5 × 10 ¹⁷ cm ⁻³ ), Zn _0.8 Cd
_0. The active layer 33 (thickness 10 nm) consisting of ₂ Se, Cl
The n-type 2-6 semiconductor layer 34 (thickness 2 μm, n = 1 × 10 ¹⁸ cm ⁻³ ) made of ZnSe added was grown by the molecular beam epitaxy (MBE) method, and the n-electrode 35 made of In (thickness) was formed. P-electrode 3 made of AuZn)
6 (thickness 300 nm) was formed by a vacuum vapor deposition method, and a reflection surface was formed by cleavage to manufacture a blue light emitting semiconductor laser.

The holes injected from the p-electrode 36 are injected from the second p-type 3-5 semiconductor layer 30 through the p-type 3-5 semiconductor layer 31 into the p-type 2-6 semiconductor layer 32. Second p-type 3
-5 The valence band edge of the semiconductor layer 30 is the p-type 2-6 semiconductor layer 3
Higher than 2, holes are easily injected. The rising voltage was as low as 4 V, and laser oscillation was obtained at room temperature.

In the above-mentioned embodiment, one p-type GaAs layer is used as the second p-type 3-5 semiconductor layer, but the present invention is not limited to this, and the p-type I whose valence band edge is higher than that of the InGaAlP mixed crystal.
Other p-type 3-5 semiconductor materials such as nP or p-type InGaAsP or multiple p-type 3-5 semiconductor layer structures may be used.

(Embodiment 4) FIG. 4 is a sectional view showing an embodiment of the fourth invention.

Second p-type 3-5 made of p-type GaAs substrate
On the semiconductor layer 40 (thickness 350 .mu.m), an In ₀ addition of _{Be. 4 Al 0. 6 P} / In 0. 6 Ga
After growing the p-type 3-5 semiconductor layer 41 composed of _(0.4-z) Al _z P strained superlattice by the gas source MBE method,
P-type 2-6 semiconductor layer 42 made of N-doped ZnSe
(Thickness 1 μm, p = 5 × 10 ¹⁷ cm ⁻³ ), an n-type 2-6 semiconductor layer 43 (thickness 1 made of ZnSe added with Cl)
^{μm, n = 1 × 10 1} 8 cm - 3) and was grown by molecular beam epitaxy (MBE) method, n electrode 4 made of In
4 (thickness 300 nm), p-electrode 45 made of AuZn
(Thickness 300 nm) was formed by a vacuum vapor deposition method to manufacture a blue light emitting diode. superlattice structure of p-type 3-5 semiconductor layer 41, a constant thickness of each layer is between 1 nm, an In _{0. 6}
Ga _(0.4-z) Al _z The Al composition z of the P layer is p-type 2-
It is 0.4 at the interface with the No. 6 semiconductor layer 42, decreases by 0.02 every cycle, and becomes zero at the interface with the second p-type 3-5 semiconductor layer 40. In this structure, the valence band edge is continuously changed, is low at the interface of the p-type 2-6 semiconductor layer 42, and is high at the interface of the second p-type 3-5 semiconductor layer 40, and the holes are easily formed in the p-type 2 -6 is injected into the semiconductor layer 42.

The rising voltage of the manufactured light emitting diode was as low as 5 V, and strong blue light emission was obtained.

Although a strained superlattice having a critical film thickness or less is used as the p-type 3-5 semiconductor layer in the above-mentioned embodiment, the present invention is not limited to this, and a superlattice having a lattice length equal to that of the p-type 2-6 semiconductor layer is used. You may use.

In the above-mentioned embodiment, one p-type GaAs layer is used as the second p-type 3-5 semiconductor layer, but the present invention is not limited to this, and the p-type I whose valence band edge is higher than that of the InGaAlP mixed crystal.
Other p-type 3-5 semiconductor materials such as nP or p-type InGaAsP or multiple p-type 3-5 semiconductor layer structures may be used.

[0026]

As described above, according to the present invention, holes can be easily injected into the p-type 2-6 semiconductor layer, the resistance at the p-electrode is reduced, and a good blue light emitting device can be realized.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an embodiment of the first invention.

FIG. 2 is a sectional view showing an embodiment of the second invention.

FIG. 3 is a sectional view showing an embodiment of the third invention.

FIG. 4 is a sectional view showing an embodiment of the fourth invention.

[Explanation of symbols]

 10 substrate 11 n-type 2-6 semiconductor layer 12 p-type 2-6 semiconductor layer 13 p-type 3-5 semiconductor layer 14 p-electrode 15 n-electrode 20 substrate 21 n-type 2-6 semiconductor layer 22 active layer 23 p-type 2- 6 semiconductor layer 24 p-type 3-5 semiconductor layer 25 p-electrode 26 n-electrode 30 second p-type 3-5 semiconductor layer 31 p-type 3-5 semiconductor layer 32 p-type 2-6 semiconductor layer 33 active layer 34 n-type 2 -6 semiconductor layer 35 n electrode 36 p electrode 40 second p-type 3-5 semiconductor layer 41 p-type 3-5 semiconductor layer 42 p-type 2-6 semiconductor layer 43 n-type 2-6 semiconductor layer 44 n-electrode 45 p-electrode

Claims (4)

[Claims] 1. A semiconductor device having a p-type 2-6 semiconductor layer made of a p-type 2-6 group compound semiconductor material containing sulfur (S) or selenium (Se), adjacent to the p-type 2-6 semiconductor layer. Then, the p-type In _x Ga _y Al _z P having a lattice length equal to or different from the critical thickness is not more than the critical film thickness.
(X + y + z = 1, 0 ≦ x <1, 0 ≦ y ≦ 1, 0 ≦ z ≦
1) It has a p-type 3-5 semiconductor layer made of a semiconductor,
The p-type 3-5 semiconductor layer has a p-electrode, the Al composition of the p-type 3-5 semiconductor layer is zero or a specific value in the p-electrode part, and approaches the p-type 2-6 semiconductor layer. A p-type electrode structure characterized by increasing continuously or stepwise as 2. A semiconductor device having a p-type 2-6 semiconductor layer made of a p-type 2-6 group compound semiconductor material containing sulfur (S) or selenium (Se), wherein the p-type 2-6 semiconductor layer is adjacent to the p-type 2-6 semiconductor layer. Then, a p-type In _{x 1} Ga _{y 1} Al having a lattice thickness equal to or different from the critical film thickness is used.
_{z 1} P / In _{x 2} Gay ₂ Al _{z 2} P superlattice (x1 + y
1 + z1 = 1, 0 ≦ x1 <1, 0 ≦ y1 ≦ 1, 0 ≦ z1
≦ 1, x2 + y2 + z2 = 1, 0 ≦ x2 <1, 0 ≦ y2
≦ 1, 0 ≦ z2 ≦ 1), a p-type 3-5 semiconductor layer, and a p-electrode on the p-type 3-5 semiconductor layer.
The energy position of the valence band edge of the type 3-5 semiconductor layer is high at the p-electrode portion, and becomes lower continuously or stepwise as it approaches the p-type 2-6 semiconductor layer. P-type electrode structure. 3. The p-type electrode structure according to claim 1, wherein a valence electron is located between the p-type 3-5 semiconductor layer and the p-electrode rather than an energy position at a valence band edge of the p-type 3-5 semiconductor layer. A p-type electrode structure having a second p-type 3-5 semiconductor layer comprising one or more p-type 3-5 group compound semiconductor layers having a high band edge. 4. The p-type electrode structure according to claim 2, wherein a valence electron is located between the p-type 3-5 semiconductor layer and the p-electrode rather than an energy position at a valence band edge of the p-type 3-5 semiconductor layer. A p-type electrode structure having a second p-type 3-5 semiconductor layer comprising one or more p-type 3-5 group compound semiconductor layers having a high band edge.