JPH0837340A - Surface emission semiconductor element - Google Patents

Abstract

PURPOSE:To provide a surface emission semiconductor element, which can lower applied voltage for emission. CONSTITUTION:In a 0.9-1.1mum band surface emission semiconductor element with GaAs/In0.48Ga0.52P semiconductor multilayer reflection films 2a and 2b, which reflects light from an active layer 3, the GaAs/In0.48Ga0.52P semiconductor multi-layer reflection films 2a and 2b perform lattice matching with GaAs between a GaAs layer and an In0.48Ga0.52P layer, and is formed via a GaInAsP layer having a band gap which is intermediate between a band gap of GaAs and a band gap of In0.48Ga0.52P.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface emitting semiconductor device, and more particularly to a semiconductor multi-layer reflective film constituting the surface emitting semiconductor device.

[0002]

2. Description of the Related Art In a surface emitting semiconductor laser device or a surface emitting type semiconductor diode, a semiconductor multilayer reflective film is used to increase the reflectance in order to reduce the threshold value and improve the luminous efficiency. Conventionally, as a material of a semiconductor multi-layer reflective film that constitutes a 0.9 to 1.1 μm band surface emitting semiconductor laser device or a surface emitting semiconductor diode, for example, as shown in Document 1, GaAs (having a high refractive index) ( Or Ga having a composition having a band gap close to that of GaAs
_{A combination of 1-X} Al _X As, X <0.1) and AlAs (or a Ga _1-X Al _X As with a composition having a band gap close to AlAs, X> 0.9) having a low refractive index Widely used. This semiconductor multilayer reflective film has a thickness of λ ₀ / 4n ₁ and λ ₀ / 4n ₂ when the emission wavelength is λ ₀ and the refractive indices of GaAs and AlAs are n ₁ and n ₂ , respectively. Yes, these are alternating combinations of these layers. With such a configuration, the absorptance can be reduced and the reflectance can be increased at the wavelength λ ₀ .

By the way, in the above-mentioned semiconductor multilayer reflective film,
GaAs (lattice constant a ₁ = 0.56533 nm) and Al
During As (lattice constant a ₂ = 0.56605 nm), a value of 0.
There is a 13% lattice mismatch. Also, in the process of forming this multilayer reflective film into a circular or rectangular mesa, Al in AlAs exposed in the air is easily oxidized, which causes a problem in reliability, and when forming a buried hetero structure, AlAs is formed. There is a problem that it is difficult to re-grow the crystal on the side surface of the layer. Therefore, a GaAs / InGaP semiconductor multilayer reflective film has been studied as a semiconductor multilayer reflective film containing no Al. Reference 1: Electron. Lett., 1989, 25, pp.1123-1124

[0004]

However, in the above-mentioned GaAs / InGaP semiconductor multilayer reflective film, GaAs is used.
A large spike-like band gap exists at the / InGaP interface, and the value is as high as 0.35 eV. for that reason,
There is a problem that a high voltage needs to be applied in order for p-type holes to overcome this band gap.

[0005]

SUMMARY OF THE INVENTION The present invention provides a surface emitting semiconductor device that solves the above problems, and has a GaAs / In _0.48 Ga _0.52 P semiconductor multilayer reflective film that reflects light from an active layer. .9 to 1.1 μm surface emitting semiconductor device, the semiconductor multilayer reflective film comprises a GaAs layer and an In layer.
Ga between the _0.48 Ga _0.52 P layer is lattice-matched with GaAs,
GaInAsP having a band gap intermediate between the band gap of As and the band gap of In _0.48 Ga _0.52 P
It is characterized by interposing layers.

[0006]

As described above, the G which constitutes the semiconductor multilayer reflective film
Between the aAs layer and the In _0.48 Ga _0.52 P layer, lattice matching is performed with GaAs, and the band gap of GaAs and In _0.48 Ga
_When a GaInAsP layer having a bandgap in the middle of the bandgap of _0.52 P is interposed, a GaAs layer and an In layer are formed.
_Since the band gap between the _0.48 Ga _0.52 P layers changes gently and the spike-shaped band gap disappears, the applied voltage for light emission can be lowered.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the embodiments shown in the drawings. FIG. 1 is a sectional view of an embodiment of a surface emitting semiconductor laser device according to the present invention. In the figure, 1 is n
-GaAs substrate, 2a and 2b are n-type and p-type semiconductor multilayer reflective films, 3 is a multiple quantum well active layer (bandgap wavelength 0.9 to 1.1 [mu] m), 4 is a current blocking layer, and 5 is an n electrode. , 6 are p electrodes. Laser cavity
The semiconductor multilayer reflection films 2a and 2b sandwich the active layer 3 and oscillate in a direction perpendicular to the substrate 1.

FIG. 2 is a diagram showing a band diagram of the semiconductor multilayer reflective films 2a and 2b. Semiconductor multilayer reflective film 2
a, 2b includes a GaAs layer 8 having a refractive index n _1, take a GaAs lattice matching, is configured by alternately stacking the In _0.48 Ga _0.52 P layer 7 having a high refractive index n ₂ than GaAs. Further, the In _0.48 Ga _0.52 P layer 7 and the GaAs layer 8 are lattice-matched to GaAs, and the band gap of GaAs (E _g : 1.42 eV) and the band gap of In _0.48 Ga _0.52 P (E _g : 1 A GaInAsP layer 9 having an intermediate bandgap of .91 eV) is interposed. GaI
The composition of the nAsP layer 9 changes stepwise in the thickness direction,
From the GaAs layer 8 side, Ga _0.62 In _0.38 As _0.27 P _0.73
(E _g : 1.55 eV), Ga _0.72 In _0.28 As _0.47 P
_0.53 (E _g : 1.65 eV), Ga _0.85 In _0.15 As
_0.71 P _0.29 (E _g : 1.77 eV). as a result,
The band gaps of the In _0.48 Ga _0.52 P layer 7 and the GaAs layer 8 are smoothly connected in a step shape, and the spike-shaped band gap disappears.

The thickness of each layer is set as follows, for example. 1) The layer thickness d ₁ of the GaAs layer 8 is λ ₀ / 4n ₁ (λ ₀ : oscillation wavelength), In _0.48 Ga _0.52 P layer 7 thickness d ₂ + GaInA
sP layer 9 thickness d ₃ is _{λ 0 / 4n a (n a} : n 2 and GaIn
The average of the refractive index of AsP). 2) Alternatively, d ₂ = λ ₀ / 4n ₂ , d ₁ + d ₃ = λ ₀
/ 4n _b (n _b : the average of the refractive indices of n ₁ and GaInAsP). 3) _{Furthermore, d 2 + d 3/2} = λ 0 / 4n a, d 1 +
and _{d 3/2 = λ 0 /} 4n b. In such a semiconductor multilayer reflective film 2a, 2b, In _0.48
Since the band gap between the Ga _0.52 P layer 7 and the GaAs layer 8 changes gently and there is no portion that changes in a spike shape, the semiconductor multilayer reflective films 2a and 2b are doped with an n or p-type impurity to increase the current. When flowing, the printing pressure voltage can be reduced as compared with the case where the GaInAsP layer 9 is not interposed.

The element of this embodiment is manufactured as follows. That is, first, n-type In _0.48 Ga in which the above-mentioned GaInAsP layer 9 is interposed on the substrate 1 by the metal organic chemical vapor deposition (MOCVD) method or the molecular epitaxy (MBE) method.
_0.52 P / GaAs semiconductor multilayer reflective film 2a, active layer 3, and p-type In _0.48 Ga with the GaInAsP layer 9 interposed therebetween.
_{A 0.52} P / GaAs semiconductor multilayer reflective film 2b is sequentially grown. Next, a circular or rectangular mesa including the active layer 3 is formed, and this mesa is embedded with the current block layer 4 to form the n electrode 5 and the p electrode 6. In this case, since the semiconductor multilayer reflective films 2a and 2b do not contain AlAs or GaAlAs, the mesas are not oxidized. Although the band gap of the GaInAsP layer 9 was changed stepwise in the above-mentioned embodiment, it may be changed continuously.

[0011]

As described above, according to the present invention, GaAs / In _0.48 Ga _0.52 P that reflects light from the active layer is obtained.
In a 0.9 to 1.1 μm band surface emitting semiconductor device having a semiconductor multilayer reflective film, the semiconductor multilayer reflective film is GaAs.
GaI lattice-matched to GaAs and having a bandgap intermediate between the bandgap of GaAs and the bandgap of In _0.48 Ga _0.52 P between the In layer and the In _0.48 Ga _0.52 P layer.
Since the nAsP layer is interposed, there is an excellent effect that the applied voltage for emitting light can be lowered.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment of a surface emitting semiconductor device according to the present invention.

FIG. 2 is a diagram showing a band diagram of a semiconductor multilayer reflective film used in the above-mentioned examples.

[Explanation of symbols]

1 Substrate 2a, 2b Semiconductor Multilayer Reflective Film 3 Active Layer 4 Current Blocking Layer 5 n Electrode 6 p Electrode 7 In _0.48 Ga _0.52 P Layer 8 GaAs Layer 9 GaInAsP Layer

Claims (1)

[Claims] 1. A GaAs / I that reflects light from an active layer.
n _0.48 Ga _0.52 P having a semiconductor multilayer reflective film 0.9 to
In the 1.1 μm band surface emitting semiconductor device, the semiconductor multilayer reflective film is formed between the GaAs layer and the In _0.48 Ga _0.52 P layer.
It is lattice-matched with GaAs and has a band gap I
A surface emitting semiconductor device characterized in that a GaInAsP layer having a bandgap in the middle of the bandgap of n _0.48 Ga _0.52 P is interposed.