JPS6257259A - Light emitting semiconductor element - Google Patents

Abstract

PURPOSE:To obtain light emitting semicoductor element which has good luminous power conversion efficiency and provides photo switching operation, by making the respective forbidden band widths of the first semiconductor layer and the fifth semiconductor layer llarger than either of the respective forbidden band widths of the second semiconductor layer, third semiconductor layer and fourth semiconductor layer. CONSTITUTION:A first semiconductor layer 1 of first conductivity type, second semiconductor layer 2 of second conductivity type, third semiconductor layer 3, fourth semiconductor layer 4 of the first conductivity type and fifth semiconductor layer 5 of the second conductivity type are formed in this order, and the respective forbidden band widths of the first semiconductor l ayer 1 and the fifth semiconductor layer 5 are made larger than either of the respective forbidden band widths of the second semiconductor layer 2, third semiconductor layer 3 and fourth semiconductor layer 4. For instance, on n-GaAs substrate 10, the crystal growth of n-type AlGaAs clad layer 1, p-type GaAs active layer 2, i-type GaAs active layer 3, n-type GaAs active layer 4, p-type AlGaAs clad layer 5 and GaAs cap layer 6 is performed. Then, an SiO2 film 7 is formed on the cap layer 6, a stripe region 12 is formed by means of the photoetching method, and thereafter a p-side electrode 8 and n-side electrode 9 are formed, thereby obtaining an element capable of laser oscillation in which the i-type active layer 3 is as thin as around 1,000Angstrom .

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a light-emitting semiconductor element that exhibits negative resistance and has functions such as light emission and optical switching.

[Prior art and problems to be solved by the invention] Conventionally, a device that exhibits this kind of negative resistance and has a light emitting function was published in the magazine "Sovlet Physics Semiconductor".
There is a photothyristor published in JIE volume 8, page 1127.

In a device using a PNPN junction, a switching operation is performed in which the PNPN junction is turned on by signal light and a large current flows to emit light. However, this device has a drawback in that the light emitting section is composed of a homojunction and the light emitting efficiency is extremely low.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate these drawbacks and provide a light-emitting semiconductor device that has good luminous efficiency and performs optical switching operation.

[Means to solve the problem]

The structure of the light emitting semiconductor device of the present invention includes a first semiconductor layer of the first conductivity type, a second conductor layer of the second conductivity type formed on the first semiconductor layer, and a second conductor layer of the second conductivity type formed on the first semiconductor layer. a third semiconductor layer formed thereon, a fourth semiconductor layer of the first conductivity type formed on the third semiconductor layer, and a fourth semiconductor layer of the second conductivity type formed on the fourth semiconductor layer. 5 semiconductor layers, each of the first semiconductor layer and the fifth semiconductor layer having a larger forbidden band width than each of the second semiconductor layer, the third semiconductor layer, and the fourth semiconductor layer. It is characterized by

〔Example〕

Next, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a sectional view of one embodiment of the present invention, and FIG. 2 is an energy band diagram of the main part of FIG. 1. In the figure, 1 is an n-type cladding layer (n-Al xn Ga 1-xnA@,
Q, 3≦xn≦08. Thickness: 0.2-3 μm Typical thickness: I It m , n-1X l 016-I X l
□tscIn-s Typical example is n”-1x 10”-5x
IQ17cm-1), 2 is the p-type active layer (p-GaA
s, thickness 30^~5oo^ Typical example is thickness 100A,
p=5 x 10? ~3 X 101'Cm - Hatake's typical example is p=5
"crn-"), 3 is an n-type active layer (non-doped Ga
A s, thickness 500^~3/Jm.

n or p≦5X10′σ″3), 4 is the n-type active layer (
n-GaAs, thickness 30A to 500A, typical thickness 10A
0A, n=5 x I Q17~3 x 1011
A typical example of 1cIni is (t=5 x 10"cm-"~t
xtots 1), 5 is a p-type cladding layer (p-AJ
xp Ga1-xp AseO, 3≦xp≦058
．． Thickness: 02-3μm Typical thickness: 1μmp=l x 1
0”~1 x 10”5cm4 Typical example is p=l x 1
0"~5XIQ"7m"), 6 is the cap layer (
p+-GaAa)7 is 8i0. 8 is an n-side electrode, 9 is an n-side electrode, 10 is an n-GaAs substrate, and 11 is an active layer including the entirety of each active layer 2, 3.4.

Figure 2 (a) is a band diagram in a thermal equilibrium state with an applied voltage O, and Figure 2 (b) is a band diagram when a voltage is applied in the forward direction of k′i and not much current flows through the device (OFF
FIG. 2C is a band diagram when a voltage is applied in the forward direction, current flows, and the active layer 11 emits light (ON state).

In the thermal equilibrium state, the type 1 temperature layer 3 is completely a depletion layer, resulting in the band diagram shown in FIG. 2(a). When a voltage is applied in the forward direction, most of the voltage is applied to the n-type active layer 3, resulting in the band diagram shown in Figure 2 (bl).A voltage can be applied further to increase the implantation, or light can be incident from outside. When the active layer is excited, 1
Carriers drift in the type temperature layer 3 due to the electric field, and electrons drift in the n-type active layer 4. The holes reach the p-type active layer 2. Since these carriers lower the potential barrier formed by the n-type active layer 4 and the p-type active layer 2, the injection becomes even larger. This type of positive feedback loop results in a band diagram as shown in FIG. 2(c), resulting in an ON state. The above operation is exactly the same as the turn-on phenomenon of a PNPN junction.

If this PNPN junction is divided into a PNP transistor and an NPN transistor, these transistors have the same configuration as a wide gap emitter transistor, so each transistor has a large gain and can be turned off even in response to weak optical signals. It is possible to move from the state to the ON state. In addition, since the light emitting section has a double heterostructure, good light emitting efficiency can be obtained.

In this embodiment, when the thickness of the n-type active layer 3 is as thin as about 1000A, laser oscillation can be performed, whereas when the type 1 temperature layer 3 is thicker, the laser oscillation is not performed and the ON state is turned on. It can emit light in the same way as a light emitting diode.

Next, a method of fabricating a device in which the n-type active layer 3 of this embodiment is thin, approximately 100 OA, and is capable of laser oscillation will be described. First, on an n-GaAs substrate 10, an n-type cladding layer 1+p-type active layer 2. ! Temperature layer 31 N-type active layer 41 P-type cladding layer 5. Cap layer 6 is crystal grown. Next, 8
An i01 film 7 is formed on the cap layer 6, and a stripe region 12 is formed by photoetching. Next, n
The process is completed by forming the side electrode 8 and the n-side electrode 9.

In this example, GaAs was used as the active layer 11, but
The material is not limited to this, and other materials such as AlGaAs mixed crystal or superlattice may be used. In this embodiment, the electrode structure is 810.
Although the membrane stripe structure is used, the structure is not limited to this, and may include a planar stripe structure, a ridge uniee, etc. 6- to 1. Other stripe structures such as an embedded eight guide structure may also be used. Further, in this example, the cladding layers were formed directly on both sides of the active layer, but the present invention is not limited to this, and a light guide layer may be provided between the active layer and the cladding layer. Furthermore, in this example, AIG a A s /G a A is used as the material.
s system was used, but the invention is not limited to this, and InGa A s P
Other materials such as /I n P type and TnGaAJA@/InP type may also be used.

〔Effect of the invention〕

As explained above, according to the present invention, the luminous efficiency is good,
Moreover, a light emitting semiconductor element capable of switching operation can be realized.

FIG. 1 is a sectional view of an embodiment of the present invention, and FIG. 2(a).

(b) and (c) are band diagrams explaining the imperial edict 1 diagram. In the figure, 1 is an n-type cladding layer, 2 is a p-type cladding layer, and 2 is a p-type cladding layer.
type hot column layer, 3 is n-type active layer, 4 is n-type active layer, 5 is n-type cladding layer, 6 is cap layer, 7 is 8401 film, 8kenn
9 is an n-side electrode, 10 is a P-hair aA8 substrate, 11 is an active layer, and 12 strip regions.

No. 11! r Figure 2

Claims (1)

[Claims] a first semiconductor layer of a first conductivity type; a second semiconductor layer of a second conductivity type formed on the first semiconductor layer; a third semiconductor layer formed on the second semiconductor layer; a fourth semiconductor layer of the first conductivity type formed on the third semiconductor layer; and a fifth semiconductor layer of the second conductivity type formed on the fourth semiconductor layer; A light emitting semiconductor device, wherein each of the forbidden band widths of the third semiconductor layer and the fifth semiconductor layer is larger than the forbidden band widths of the second semiconductor, the third semiconductor, and the fourth semiconductor.