JPS6386483A - Semiconductor light-emitting diode - Google Patents

Abstract

PURPOSE:To enable an end face light emission which is stable against the temperature and has small temperature dependency of output light by sequentially stacking in part of the current injection region, contacting with an active layer having a low band gap energy value (E value), a semiconductor layer of the same conductivity type having a high E value, then a semiconductor layer having a moderate E value, and a semiconductor layer of a different conductivity type having a high E value. CONSTITUTION:This semiconductor light-emitting diode has a double hetero junction structure in which an active layer of a first conductivity type is formed on a substrate. The active layer has a band gap energy Eg=Eg. The diode also includes a striped light emitting region. In part of the current injection region, there is provided a semiconductor structure comprised of, sequentially stacked and contacted with the active layer, a semiconductor layer of the first conductivity type and Eg=Eg2 (Eg2>Eg1), a semiconductor layer of the first conductivity type and Eg=Eg3 (Eg1<Eg3<Eg2) and a semiconductor layer of a second conductivity type and Eg=Eg4 (Eg4>Eg3). This LED has a high fiber coupling output and the temperature stability of the optical output is remarkably high.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a semiconductor light emitting diode (hereinafter referred to as LED) suitable for optical fiber communication. In brightness,
A high fiber coupling power is important. Conventionally,
As an LED with high fiber output, an edge-emitting LED has been developed that has a striped light emitting region and does not take out light from the edge of the stripe (Optical Communication Device Engineering. Kogaku Tosho, (1983) p. 12g-134). . Edge emission L
In the ED, since the light emitting region is striped, the gain region length is long and the stimulated emission light component is large, making it easy to increase the output.

(Problems to be Solved by the Invention) However, the above-mentioned conventional LED has a drawback that the stimulated emission light component is large, so that the temperature dependence of the light output is large. Since devices equipped with LEDs are used under various environmental temperatures, the large temperature dependence of the light output of LEDs has been a serious problem in practice. Therefore, it was necessary to control the temperature with a cooler such as a Bertier element, or to compensate for the temperature with an electronic circuit. However, coolers have the drawbacks of being expensive and large in size. In addition, compensation using an electronic circuit is difficult to sufficiently compensate for large changes in optical output, and the circuit becomes complicated.

SUMMARY OF THE INVENTION An object of the present invention is to provide an edge-emitting LED whose light output is stable with respect to temperature and whose temperature dependence is small.

(Means for Solving the Problems) Means provided by the present invention in order to solve the above-mentioned problems and achieve the above-mentioned objects is to provide a first conductivity type on a semiconductor substrate,
The band gap energy (hereinafter referred to as Eg) is E g
, -E g I is provided with a double hetero stacked structure having an active layer, and has a stripe-shaped light emitting region, the semiconductor light emitting diode having a stripe-shaped light emitting region, wherein a part of the current injection region is in contact with the active layer. Eg-Egg (Egx
>Egs) and a semiconductor layer of Eg-E with the first conductivity type.
gs (Eg□<E ga <E ga ) and the second conductivity type, Eg” Ega (Ega>Egs
) are sequentially laminated to form a semiconductor structure.

(effect) The operation of the present invention will be explained below with reference to the drawings.

FIGS. 2(a) and 2(b) are cross-sectional views of the device in a plane parallel to the stripes for explaining the principle of the LED of the present invention;
and the energy band diagram, respectively, and the bandgap energy E g in a portion of the stripe.
” A p-type semiconductor J!1 of Egz (Egx > Eg+) is in contact with the p-type semiconductor active layer 11 of Eg, t.
12, Eg-Egs (Eg+ < Egg < Egg
) p-type semiconductor layer 13, and Eg-Ega (Ega>
Egj) n-type semiconductor layers 14 are formed in this order. Hereinafter, this area will be referred to as the output control area 15. - The other part of the horizontal drive is in contact with the active layer 11, and E g > E g
One n-type semiconductor layer 16 is formed.

Hereinafter, this area will be referred to as the main light emitting area 17.

q') When a current is passed in the forward direction to the LED, the main light emitting area 1
7, active J! At 11, light emission occurs due to recombination of electrons and holes. On the other hand, in the output control region 15, first the semiconductor 7
At 113, recombination of electrons and holes occurs, and some of the electrons become
It flows into the active layer 11 over the heterobarrier of the semiconductor 1113 and the semiconductor J'1i12, and recombines with holes. The leakage current flowing across this heterobarrier increases with increasing temperature. Therefore, the light emission in the active layer within the output control region 15 increases as the temperature rises.

At low temperatures, the amount of light emitted from the active layer in the output control region 15 is small, so light guided in the active layer in the stripe direction is largely absorbed in the output control region 15. However,
As the temperature increases, the light emission in the active layer in the power control region 15 increases, so the absorption in this region 15 decreases. This change in absorption cancels the temperature change in the emission intensity in the active layer of the main light emitting region 17, reduces the temperature change in the output light intensity of the LED, and provides stable operation.

(Example) Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows a device according to an embodiment of the present invention, and is a sectional view taken in a plane parallel to striped light emitting regions. p-type I
On the nP substrate 10, p-type 1nP151B, p-type InGa
AsP active layer 11 (E g r = 0.95e'/
), then the n-type InP layer 16 is formed in order.
After partially removing the P layer 16, selectively p-type InGaAs
PJI (E gt ” 1.3eV) 12, p-type I
nGaAsPJ! (E gs = 1. let/
) 13. Form an n-type InP layer 14 in order. n-type In
510. on the surfaces of the P layers 14 and 16. A film is formed, 5 lots are selectively removed in a stripe pattern, and the n-type electrode 19 is made of Au.
Zero-order p-type InP substrate 10 formed by GeNi vapor deposition
After polishing, a p-type electrode 20 is formed by vaporizing AnZn. Among the striped current injection regions, n-type InPW1
16 is the main light emitting region 17, which is made of p-type InGaAs
The area including PJi 12 becomes the output control area 15.

A forward current is applied to this LED. First, at low temperatures, as described in the (effect) section, the electron leakage current injected into the active layer in the output control region 15 is small, so the active layer in this portion becomes an absorption region with large absorption. As the temperature rises, the electron leakage current injected into the active layer in the output control region 15 increases, and the absorption decreases accordingly. As a result, the temperature change in the emission intensity in the active layer in the main light emitting region 17 was canceled out, and the temperature dependence of the output light of the LED was significantly reduced as shown in FIG.

(Effects of the Invention) As explained above, the LED of the present invention has high fiber-coupled output and extremely high temperature stability of the optical output. The present invention has such effects.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing one embodiment of the present invention, and FIG.
) is a sectional view showing the principle structure of the present invention, FIG. 2(b)
3 is a diagram showing the bandgap energy Eg in the structure of FIG. 1A, and FIG. 3 is a temperature characteristic diagram of the embodiment shown in FIG. 1 and the conventional edge-emitting LED. In the figure, 10 is a semiconductor substrate, 11 is an active layer, and 12 is Eg-
Egg semiconductor layer, 13, Egg-Egg semiconductor layer, 1
4 indicates a semiconductor layer where Eg=Ega. 10 n-1nP, 1IL17 Main emission/91 sense 1
1 p-1nGaAsP, 55ji layer (Eg=Eg+
) 18 pJnP412 p-1nGaAsP
4 (E9=E92) 19 n-7y413
P-1nGaAsP4 (E9=EQ3)
20 P'f&14 n -1nP4 (E
9=E94) 15 pupuru/control insert pawl 16 n-1nPJ Fig. 1 11 ρ9! Shin conductor 3S outer layer (Eg=Eg+) 12
pi! ll'F4(Eg=Eg2)13 ρwy
4 rows (E9/E93) 14 n4tJI↓warehouse 4 (
Eg = Eg &) 15 Muka ← Control inclination + 6 n type + 14-no book / 1) 171 Starting extension and healing 19 n electric b 20 ρ electrode 2nd figure field /L (@C) Fig. 3

Claims (1)

[Claims] In a semiconductor light emitting diode having a stripe-shaped light emitting region, a double hetero stack structure having an active layer of a first conductivity type with Eg=Eg_1, where band gap energy is Eg, is provided on a semiconductor substrate, and A semiconductor layer of the first conductivity type with Eg=Eg_2 (Eg_2>Eg_1) and a semiconductor layer of the first conductivity type with Eg=Eg_3 (Eg_1<Eg_1).
_3<Eg_2) and a semiconductor layer of the second conductivity type, Eg=
A semiconductor light emitting diode characterized in that a semiconductor structure in which semiconductor layers Eg_4 (Eg_4>Eg_3) are laminated in order is provided in a part of a current injection region in contact with the active layer.