JPS5955085A - Semiconductor light emitting device - Google Patents

Abstract

PURPOSE:To obtain a basic zero order lateral mode having high quantum efficiency and high stability by arranging a striped semiconduct or layer, and further introducing a loss guide, thereby generating an ultrashort pulse light. CONSTITUTION:Both P type InP layers 15 and 14 have impurity density of 1X 10<18>cm<-3>, and an N type InGaAsP layer 16 has an impurity density of approx. 1X10<17>cm<-3>. Thus, the width Xn in the layer 16 of a depletion layer 20 expands approx. 10 times of the width Xp in the layers 15, 14, and if the applied voltage is maintained at the degree for causing an Avalanche breakdown when the thickness of the layer 16 between the layer 15 and the P type InGaAsP region 17 is 0.5-1mum, the layer 20 in the layer 16 reaches the P type region 17 to energize the pulse current. Since the layer 15 is striped, the current is effectively narrowed. Further, the forbidden band width of the layer 16 is narrower than the forbidden band width, and the loss guide that the light extended from the layer 13 is absorbed by the layer 16 is formed.

Description

Detailed Description of the Invention (a) Technical Field 1 of the Invention The present invention relates to a semiconductor light emitting device, particularly a semiconductor light emitting device, which generates sub-nanosecond ultrashort pulse light with excellent quantum efficiency, and which is stable and has a 9' fundamental zero-order transverse mode. The present invention relates to a semiconductor light emitting device that can be easily obtained. ■ (b) ``''', Background of the m technique ・1□ In optical technology, the direct high-speed modulation operation of semiconductor lasers and the high-speed response characteristics of photodiodes are utilized:
However, these operations are exactly below 1 to 2 GHz'(GHz')□. □On the other hand, the bisecond range has already been developed in fixed-short nizor and dye laser spectroscopy, and is playing a major role in fields such as measurement, physical properties, and nuclear fusion.

Semiconductor lens lasers have a wide gain bandwidth due to rounding using band-to-band transitions, a large gain, and a short cavity length, resulting in short photon lifetimes and cavity regularization l17. - L7 is extremely short between L7 and L7, which is essentially suitable for generating ultrashort pulse light, and the previous jF
In addition to the fields of application of 2, applications such as ultra-high-speed optical transmission are expected in the future.

(c) Conventional techniques and problems Semiconductors that generate ultrashort pulse light - the already known information
An example of this is shown in FIG. 1 as a sectional view 1.

In the figure, 1 is an n-type gallium arsenide (GaAs) substrate, 2 is an n-type potassium aluminum arsenide (GaAA) substrate, and 2 is an n-type potassium aluminum arsenide (GaAAs) substrate.
! As) layer, 3 is n-type or p-type GaAs active layer 1, 4 is I)! +1! JGaAIAs layer, 5 is n-type Ga
As7ff, 6 is a p-type GaAs region formed, for example, by zinc (Zn) diffusion, 7 is a p-side electrode, and 8 is an n-side electrode.

In the semiconductor laser of this conventional example, a PnP junction is formed by the p-type GaAs region 6, the n-type GaAs layer 5, and the p-type GaAlAs layer 4. If a negative voltage is applied between the electric current and the electric current,
The n-p junction between the n-type GaAs/@i 5 and the p-type GaAlAs m4 is reverse biased to form a depletion layer across this junction. When the applied voltage is large, this depletion layer becomes pffi! i'+ reaches the GaAs region 6, and p-
n-1) A sub-nanosecond pulse is applied to the junction, causing a flow of Ga.
Ultrashort pulse light is oscillated in the As active layer 3.

However, in the semiconductor laser of this conventional example, the current confinement depends only on the impurity diffusion width of the p-type GaAs layer 6, and the minimum impurity diffusion width is about 5 [μm]. Furthermore, since the transverse mode of the laser beam does not have a refractive index kit and only has a gain guide based on current concentration, the quantum efficiency is low and the transverse mode is unstable.

(d) Purpose of the Invention The present invention provides a half-unit light-emitting device that is equipped with a p-n-p junction, generates ultrashort pulse light, and provides a stable fundamental zero-order transverse mode with high quantum efficiency. The purpose is to

(e) Description of the Invention The object of the present invention is to form a first semiconductor three-integrated layer of the 14th electric type, and to form a semiconductor layer in contact with the first semiconductor layer such that the forbidden band width is smaller than that of the first semiconductor layer. a second semiconductor layer that is in contact with the second semiconductor layer and has a larger forbidden band width than the second semiconductor layer;
a conductive type third semiconductor layer and a striped semiconductor layer in contact with the third organic layer;
and a fifth semiconductor layer of a first conductivity type whose forbidden band width is smaller than that of the fourth semiconductor layer, and a fifth semiconductor layer disposed in a region corresponding to the fourth semiconductor layer via the fifth semiconductor layer. A semiconductor light-emitting device comprising two barrels and a sixth semiconductor region of the type υ
achieved.

In particular, by making the forbidden band width of the fifth semiconductor layer smaller than the forbidden band width of the second semiconductor layer, a lateral loss guide is formed in the optical waveguide.

Furthermore, by making the impurity concentration of the fifth semiconductor layer smaller than the impurity concentrations of the third and fourth semiconductor layers, it is possible to reduce the thickness of the third semiconductor layer. Therefore, the effect of the loss guide can be fully utilized.

(f) Embodiments of the Invention The present invention will be specifically described below by way of embodiments with reference to the drawings.

FIG. 2 is a sectional view showing a first embodiment of the present invention.

In the figure, 11 is the impurity concentration 1×10"'Cc1n"
12 is an n-type InP substrate with an impurity concentration of about 5×10'm[m-'', :I].
/ijN, 13 is an n-type or p-type indium-gallium-arsenic-phosphorus (InGaAsP) active layer, 14 is a p-type InP layer with an impurity concentration of about IXIQn (m-''), 15
is a striped p-type InP layer, which in this embodiment has the same composition and impurity concentration as the Ni14.

A narrower composition has been selected. 17 is the impurity concentration I
A p-type InGaAsP region of about 10"(cm-"), 18 is a p-side electrode, and 19 is an n-side electrode.

In this example, an n-type InP layer 12 is formed on an n-type InP substrate 11 to a thickness of 1 to 2 μm (E&i degrees), and an InGaAs P active layer 13 is formed to a thickness of 0.1 μm, for example, on an n-type InP substrate 11 by liquid phase epitaxial growth. Then, the layers 14 and 15 are integrated to form a p-type InP layer with a thickness of, for example, about 1.5 to 2 [μm'1].

Next, a photolithography method and a chemical etching method are used to make the cross-sectional shape of the p-type InP layer convex. The flat part of the p-type InP layer constituting the layer 14 of this embodiment has a thickness of about 0.2 to 0.5 [μm''1], and the striped curved part constituting M15 has a width of 2 to 5 [μm]. That's about it.

Next, n-type In was grown again by liquid phase epitaxial growth.
After forming the GaAsP layer 16 to a thickness of, for example, 2 to 3 [μm] in the thickest region, silicon dioxide (S
Using a film of silicon nitride (SijN4) or silicon nitride (SijN4) as a mask, an acceptor impurity such as zinc (Zn) is thermally diffused from the surface of the previous H-bin type InGaAsP layer 16 to form a p-type InGaAsP region 17. .

However, in this embodiment, the p-type InGaAsP region 17
and the n-type InGa-A left between the p-type InP layers 15 and 9.
The thickness of the sP layer 16 is approximately 0.5 to 1 [μm''1], and the width of the p-type layer nGaAsP region 17 (length in the width direction of the striped p-type InP layer 15) is 5 to 20 [μm''.
Iku] degree. And p-side electrode 18 and n-side electrode 19
is formed by conventional techniques. In this embodiment, the p-type InGaAsP region 17 is made of n-type InGaAsP by diffusion.
Formed within the aAsP layer 16, n-type In nGaAsP
p-type InGaAsP selectively or entirely on Jfi 16
It is also possible to stack layers.

In the semiconductor light emitting device of this embodiment described above, the p-side electrode 18
If a voltage V is applied that makes n-side electrode 19 positive and n-side electrode 19 negative, n
The type InGaAsP layer 16 and the puInPffi 15 and 14 are not in a reverse bias state, and a depletion layer 20 shown by the line W is formed across the interface therebetween. The width of this depletion layer 20 is expressed as WS width W, the width in the p-type layer is expressed as Xp, and the width in the n-type layer is expressed as Xn. Concentration k: It is already known that it is a proportionality constant.

In this example, the impurity concentration and NA of the p-type InP layers 15 and 14 are 1xLo''(m-'')t n-type InP layers 15 and 14.
The impurity concentration ND of the GaAaP layer 16 is 1xlO" (cm
-”), empty: two-layer 20 n-type InGa
The width Xn of AsP layer 16 is equal to the width Xp of p-type InP layers 15 and 14.

It spreads about 10 times, and the p-type InP layer 15 and p, m I
n'IJI In between nGa-AsP region 17
When the thickness of the GaAsP conductor 16 is 0.5 to 1 [μm], the applied voltage is set to 2.5 to 5 [V] and maintained at that value, that is, the voltage is maintained to the extent that avalanche breakdown occurs. Then, the depletion layer 20 in the n-type InGaAaP layer 16 reaches the p-type InGaAsP region 17, and a pulsed current flows through this semiconductor light emitting device.

8- If the stripe width of the p-type InP layer 15 is 80, the width S through which this current flows is So + 2Xn-i= So +
2 W, for example 50=3 [μm], W-0.5
If it is [μm], it is S+4 [μm], and the current confinement is effectively performed.

In this example, the forbidden band width of the n-type InGaAs P layer 16 is narrower than the forbidden band width of the InGaAsP active layer 13 (the light seeping out from the InGaAsP active layer 13 does not exist in the p-type InP layer 15! In the area n 壓 InGa
The AsP layer 16 constitutes a loss guide that can be absorbed. In particular, if the impurity concentration NA of p-type InP [14] is high as shown earlier in 2015, depletion within the p-type InP [10. Since the width Xp of the P By Xnp layer 14 is small, it is possible to reduce the thickness of the P By Xnp layer 14 to, for example, about 0.2 [μm], and the effect of the loss guide is fully exhibited.

FIG. 3 is a sectional view showing a second embodiment of the present invention, and the same reference numerals as in FIG. 2 indicate the same parts.

The second example of this year is a striped p-type semiconductor, 4
[15' is p type tnPJ even 14 means composition spectroscopy - p
It is formed of type InGaAsP.

That is, in this embodiment EO, the h height of the p-type InP layer 14 is set to 0.2 to 0.3 μm during epitaxial growth.
m], and then a p-type InGaAsP layer 15' is gradually grown to a thickness of, for example, 1.2 to 1.5 [pm].
Due to the difference in composition between both layers, p-type InGaAsP j
The shape of both layers is stabilized by etching the layer 15' in a stripe pattern. s'i InGaAaP layer 15'? request
In order to prevent the light seeping out from 113 from being absorbed, it is desirable that the

As described in the detailed description of the invention, according to the present invention, the arrangement of the striped half-layers (15, 15') is sufficient to limit the spread of the depletion layer turned on. The current confinement is performed to increase the quantum efficiency, and it is possible to generate high-output pulsed light with a small amount of current.

The gain guiding effect also increases for the t & transverse modes, but
Furthermore, the transverse mode can be changed to 1 by introducing the above-mentioned ``kite''. It is stable [-, and the zero-order transverse mode of two swords can be easily realized.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view showing a conventional example of the short-pulse Eiji one-body laser, Fig. 2 is a cross-sectional view showing four examples of the present invention, and Fig. 3 is a cross-sectional view showing four examples of the present invention.
This is a cross-sectional view showing an example of one Shu and Ming immortal fruit. In the figure, 11 is an n-type InP substrate, ]2 is n-)I
nP scrap, 13'ti InGaAsP active layer, 14 p-type InI) layer, 15 p-type InP layer, 15' p-type I
nGaA+qP JH 116 is an n-type InGaAsP layer, 17 is a p-type InGaAs P region, 18 is a p-side electrode, 19 is an n-side electrode, and 20 is a depletion layer. Sawa Sukiko 422-

Claims (1)

[Claims] (A first semiconductor layer of a first conductive layer and a first semiconductor layer in contact with the first semiconductor layer) Prohibited @ 76 with a small width
$2 semiconductor layer, a third semiconductor layer of a second conductivity type that is in contact with the second semiconductor layer and has a larger forbidden band width than the second semiconductor layer, and is in contact with the third semiconductor layer. a fourth semiconductor layer of the second ≠ electric type, which has a second semiconductor layer and has a larger forbidden band width than the second semiconductor layer, and covers the third and fourth semiconductor layers; and the third and fourth semiconductor layers have a predetermined band width of Φ,
A fifth semiconductor of the a^1 conductivity type '/fi with a small
A semiconductor/body light-emitting device characterized by □ a '6th semiconductor region of a second conductivity type disposed through a layer, as shown on the left. □(2) The forbidden band width of the semiconductor layer of 5 above is equal to that of the second semiconductor layer.
The semiconductor light emitting device according to claim 1, wherein the forbidden band width of the semiconductor layer is smaller than that of the semiconductor layer. (3) Claim (1) or (2), characterized in that the impurity concentration of the fifth semiconductor layer is lower than the impurity concentration of the third and fourth semiconductor layers. semiconductor light emitting device.゛