JPS594193A - Semiconductor light emitting device - Google Patents

Abstract

PURPOSE:To obtain a light output waveform of high efficiency, low threshold, preferable linearity and high quality by arranging a semiconductor layer having a refractive index larger than a clad layer arranged selectively at least one of the first and second clad layers and the first hole drawn with a light emitting region in the active layers, and a semiconductor layer having a the second hole smaller than the first hole for drawing a current path on the clad layer between the previous semiconductor layer and the active layer. CONSTITUTION:A current path width S is specified by two current enclosure layers 9, and formed smaller than the light emitting width specified by two light enclosure layers 5. Accordingly, after the current passes the layer 9, the W, S and the thickness of the second clad layer 4 can be selected so that the current path width does not exceed the light emitting width W even if the width is slightly extended, thereby almost eliminating the reactive current component. Thus, even if the light emitting width S is reduced, the oscillating threshold current can be reduced, and the differentiated quantum efficiency can be increased. Accordingly, the area of the light emitting unit can be reduced. In this manner, moderating vibration in which speed characteristics can be suppressed, and preferable light output waveform can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to a semiconductor light emitting device, and more particularly to improvements in a semiconductor laser device.

(bl) Prior Art and Problems A semiconductor laser device having a double heterojunction structure made of InGaAsP/InP is seen as a promising light source for long-distance, large-capacity optical transmission using a single mode fiber.

The inventors of the present invention have developed a high
In order to reduce the rate and darkness value, in patent application No. 57-015617, light and current are confined in one layer (Self
-Aligned) structure of InGaAsP/InP
An application was filed for a double heterojunction semiconductor radar device. This semiconductor laser device is designed to achieve high efficiency coupling with an 11-mode fiber, and is designed to achieve a single transverse mode, stabilization, and low threshold. The main structure is shown below.

In the figure, 1 is a semiconductor substrate made of, for example, n-type 1nP, and 2 is a semiconductor substrate formed on the semiconductor substrate 1''.
3 is an active layer of e.g. InGaAsF grown on the first crat layer 2'; 4 is an active layer of e.g.
A second flano layer 1, 5 consisting of n I) is selectively disposed within the second flan F layer 4, for example, an n-type flano layer 5.
A high refractive index layer made of GaAsP, 6 is an ohmic contact layer made of, for example, p-type 1nGaAsl, grown on the second cladding layer 4''.

7 is a p-side electrode formed on the ohmic contact layer 6, for example, made of 1' i P I to u; 8 is made of, for example, AuGeN formed on the back surface of the semiconductor MJIi+.
This is an n-side electrode made of i-alloy.

The above semiconductor 1t1/-! As seen in the figure, at least one of the clamps l' IM 2 and IM 4 disposed on both sides (L:1''-lower in the figure) of the active it33, as seen in the figure, In the second clan 1j-4, a layer having a refractive index Jjr that is 1r11 higher than that of the second cladding layer 4 is selectively buried and formed. , the second j11 refractive index layer is the second
The light-emitting region 3' is defined in the active layer 3 and is selectively provided by setting a Z1 stripe. l! ll l-) In the same figure, the light emitting region 3° is defined in the shape of a strip with a width W by the existence of a high refractive index 1r+5.

On the other hand, the current flowing from the p fullll current 4tti 7 does not flow into the n-type high refractive index layer 5, and therefore the current path also has a width of approximately W due to the presence of the high refractive index layer 5. Defined in stripes.

According to the structure shown in FIG. 1 as in the above tree, the width of the current path and the width of the light emitting region are approximately equal due to the presence of the high refractive index layer 5. Therefore, there is no current and the J component is small, so 1) ii differential 117
7. A high-quality semiconductor laser device with excellent completion efficiency, low threshold value, and linearity can be obtained.

However, as a result of various experiments, it was found that there were still problems with the conventional structure as described in (U7) when the elements were miniaturized.

That is, as shown by the arrow in FIG. 2 (IT-H sectional view), the current flowing from the n-side electrode 7 has a high refraction 4=lW5 after passing through the region sandwiched by the high refractive index j-5. bottom B [i to i
(2) When the channel reaches the active layer 3, the width of the channel is equal to the W
It becomes slightly wider, and becomes W+2ΔW. The current flowing in this portion of ΔW becomes an ineffective component that does not contribute to light emission, but when the channel width is large, its influence is relatively small and can be ignored. However, when the channel width W is narrowed to, for example, 5 [μm], the proportion within 1 of this infinite h component becomes large. Therefore, there is a problem that the 11' Y-sensitivity decreases and the dark value current increases. 1-Conventional structure &(
It takes a lot of trouble! , occurs when the channel width is approximately 7 (11 m3 or less) or less.

(C]) The 1:1 aspect of the invention is to provide a semiconductor light emitting device that has high efficiency, low threshold value, good linearity 2 and high quality optical output waveform even when the pattern is miniaturized. It is about providing.

(di Structure of the Invention The characteristics of the present invention include a semiconductor substrate, a semiconductor layer forming a first cladding layer formed on the semiconductor substrate 1-, and a semiconductor layer formed on the semiconductor layer forming the first cladding layer. life)
a semiconductor layer constituting 11 layers, a semiconductor layer constituting a second crat layer on the semiconductor layer constituting the active layer, and at least one of the semiconductor layers constituting the first and second crat layers. A first layer having a refractive index thicker than the selectively disposed crat layer and defining a light emitting region that reaches the active layer.
a semiconductor layer having an opening of !, and defining the light emitting region! 1 (a second opening smaller than the first opening defining a current path in the cladding layer between the conductor layer and the active layer);
A semiconductor layer having an opening I] is disposed.

[Ql Embodiments of the Invention In the present invention, the problem with narrowing the -1 series current path width is that in conventional semiconductor light emitting devices, the current path width and the light emission width are the same in the high refractive index layer 5. This was done from the perspective that this is due to the fact that it is defined by the (confinement layer). Therefore, in the present invention, the conventional high refractive index layer 5 is used as an optical confinement layer, and a current confinement layer is provided directly below the optical confinement layer, and the width of the current confinement layer is made smaller than the width of the optical confinement layer. By doing so, the light emitting region lN11 and the current path width in the active layer are made approximately equal to each other, thereby attempting to eliminate the conventional problem when the pattern is made finer.

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 3 shows an n-type 1nP waveform (radiation using a plate, 1.3 Cμm IA) 4tFIn as an embodiment of the present invention.
FIG. 2 is a sectional view of a main part of a GaAsP/I n PL/-41' device.

In this figure, parts that are the same as those in FIG. 1 are designated by the same reference numerals. That is, I-, l is a semiconducting substrate made of n-type 1nP and has a thickness of about 100 (#m), 2 is a first flannel 1-1m1 made of n-type 1nP and has a thickness of about 2 (l1m), and 3 is a Photoluminescence wavelength λpl = 1.3[:μm
] and the activity 1m consisting of the AND θ month nG + 1Asr'
1 has a thickness of approximately 0.2 (#m), 4 is a second cradle IN made of p-type 1+P and has a thickness of approximately 0.1 [μm], 5
For example, the photoluminescence wave 14λpl=1.3Cμ selectively arranged and formed in the second clan 1j-4
mll n-type InGaAs1'' to IC
i refractive index In (light confinement layer) and thickness approximately 0.8 (
Met m, 'l, G is -1- second crat layer 4
) A1-luminescence wavelength λp1-
1.3(〆zn) n-type 1nGaAsP layer for ohmic contact, 7 and 8 respectively p-side electrode and n(
It is an IllI electrode.

Further, in this embodiment, a photoluminescence wavelength λpl=1.0 is provided immediately below the high refractive index layer 5 made of n-type 1nGaAsP and in contact with the high refractive index layer 5. A current confinement layer 9 made of r1 type 1nGa sieve P of I Cpm) and having a thickness of approximately 0.2 (umll) was disposed and formed. The width S of the stripe-shaped region sandwiched between the two optical confinement layers 5 is made smaller, and the thickness of the current confinement layer 9 is made smaller by about 0. 5(me!m') or less.

The current path 11m1S is defined by the two current confinement layers 9, and is formed to be smaller than the emission width defined by the two light confinement layers 5. Therefore, even if the current expands slightly after passing through the current confinement layer 9, the width of the current 1-6 should not exceed the emission width W.

It becomes possible to select the thickness, etc. of the second crank F' and set the second crank F' (4), and the reactive current component is almost eliminated.

Therefore, even if the emission width S is made small, the oscillation dark value current can be made small and the differential quantum 'lJJ rate can be corrected. Therefore, since the area of the light emitting section can be made small, the relaxation oscillation that occurs at high speeds is suppressed, and a good optical output waveform can be obtained.

FIG. 4 is a curve diagram that does not show the characteristics of the semiconductor light emitting device of the above-mentioned example, and as shown by the solid line, the dark value current is approximately 50 (mA),
A differential quantum efficiency of 0.25 (mW/mA) was obtained,
The optical output-current characteristics have good linearity.

Note that the broken line indicates the characteristics of the semiconductor light emitting device of the conventional structure excluding the current confinement layer in the tenth embodiment, and the effects of the present invention will be easily understood when compared with this.

The present invention is not limited to the above-mentioned embodiments, but can be implemented with various modifications.

For example, the composition of the current confinement layer 9 is selected so that the refractive index is smaller than that of the active layer 3 and larger than that of the second ground layer 4 in the embodiment described in -. The composition of the ingredients is not limited. The refractive index of the current confinement layer 9 may be equal to or lower than the refractive index of the active layer 3 and equal to or greater than the refractive index of the ground layer in which the current confinement layer 9 is provided.

Therefore, the current confinement N9 is not limited to InGaAs P shown in the second embodiment, but may be made of InP.

In addition, the current confinement layer 9 is written as in the embodiment.
It may be formed in contact with the two-layered optical confinement layer 5 or separated from it, and in short, it is necessary to be disposed close to the active layer 3. That is, in order to effectively confine light, it is necessary that the distance between the light confinement layer 5 and the active layer 3 be equal to or less than the above-described distance (<0.5ClJm). The current confinement It+f 9 should be formed within this range.

21' conductor light emitting device according to the present invention.
It is also possible to implement using an IAs-based compound semiconductor.

In addition, when carrying out the present invention, the p-type and n-type of the above-mentioned embodiment
You can also reverse the pattern entirely.

Furthermore, it is unnecessary to particularly explain that the conductivity type of the optical confinement layer 5 may be either p-type or n-type.

if) Effect of the invention 0 1u-1-As explained in 7, according to the semiconductor light emitting device of the present invention, even if the emission width is made finer, the height 1 rate, the low threshold value, and the good straight line 171 are maintained, and the H A high quality optical output waveform can be obtained.

[Brief explanation of the drawing]

1 and 2 are a perspective view and a sectional view of a main part for explaining the problems of a conventional semiconductor light emitting device, FIG. 3 is a sectional view of a main part showing an embodiment of the invention, and FIG. FIG. 3 is a curve diagram showing the effects of IL-Example. In the figure, ■ is a semiconductor substrate, 2 is the first cluster, and 7 is the semiconductor substrate.
H53 is an active 11J double layer, 4 is a second clan layer, 5 is an optical confinement layer, 6 is a layer for ohmic contact, and 9 is a current confinement layer. Agent Patent Attorney Hiroshi Matsuoka Department 1 Figure 1 Figure 2

Claims (1)

[Claims] a semiconductor substrate; a semiconductor layer forming a first cladding layer formed on the semiconductor substrate; a semiconductor layer forming an active layer formed on the semiconductor layer forming the first cladding layer; A semiconductor layer constituting a second cladding layer on a semiconductor layer constituting an active layer, and the cladding layer selectively disposed on at least one of the semiconductor layers constituting the first and second cladding layers. a semiconductor layer having a large refractive index and a first opening that defines a light emitting region in the active layer, and a current path is provided in a cladding layer between the semiconductor layer that defines the light emitting region and the active layer. defining said first
1. A semiconductor light emitting device comprising: a semiconductor layer having a second opening smaller than the second opening;