JPS6062180A - Semiconductor light emitting element - Google Patents

Abstract

PURPOSE:To produce the title element with excellent light emitting efficiency eliminating any current leakage channel by a method wherein, in a buried type semiconductor light emitting device with buried layers at both sides of a double hetero structure, the buried layers are composed of a lower layer comprising mixed crystal of InP or GaInAsP and an upper semi-insulating AlxGa1-xAs layer formed by organic metallic vapor growing process. CONSTITUTION:An N type InP layer 7 as a lower clad layer is coated with an active layer 8 whereon an N type upper clad layer 9 is deposited to form a double hetero structured light emitting element. Next both sides of the layer 9 including a part of the layer 7 are removed from the surface leaving the central part as a stripe. Later, the removed parts at both sides are buried in buried layers 10 to be current strangulating layers. At this time, the layers 10 are composed of a laminated body of a lower layer comprising non-doped InP or GaAsP coming into contact with the substrate 7 and an upper layer comprising semi- insulating AlxGa1-xAs. Through these procedures, the energy gap of the layers 10 may be augmented to restrict the current flowing therein.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention relates to a buried type semiconductor light emitting device having a structure having buried layers as current confinement layers on both sides of a double heterostructure.

(Description of Prior Art) First, before entering into a description of the present invention, a conventional buried type semiconductor light emitting device of this type will be described using a semiconductor laser as an example.

FIG. 1 is a diagram showing the structure of a conventional InP-based semiconductor laser in a cross section taken along an arm opening. As shown in FIG. 1, the double heterostructure of this laser includes a lower cladding layer 1 made of n-1nP and an active layer 2 made of Ga1nAsP.
A reverse bias buried layer 4 to serve as a current confinement layer is formed outside this double heterostructure, and this buried layer 4 is connected to the lower p-InP layer. 5 and an upper n-InP layer 6. However, in this configuration, the lower p-1nP layer 5 extends over and is in contact with both the upper and lower cladding layers 1 and 3 with the active layer 2 at the center, so the cladding layer 5 is Layer 3 → P-I
There is a current leakage path from the nP layer 5 to the cladding layer l, which has the disadvantage that current leakage occurs in a high injection region where the injection current is large and the output is saturated.

Furthermore, in the InP system, epitaxial growth of semi-insulating crystals has not been achieved with conventional techniques, and there is a drawback that this semi-insulating crystal cannot be used as a buried layer.

(Object of the invention) The object of the present invention is to eliminate the current leakage path as described above,
Moreover, it is an object of the present invention to provide a semiconductor light emitting device having a semi-insulating crystal as a buried layer and having high luminous efficiency.

(Structure of the Invention) In order to achieve this object, in the semiconductor light emitting device of the present invention, the buried layer serving as the current confinement layer is made of InP.
Or semi-insulating An
1-XAS.

(Description of Embodiment) Hereinafter, one embodiment of the semiconductor light emitting device of the present invention will be described with reference to FIG.

FIG. 2 shows an example of the semiconductor light emitting device of the present invention.
1 is a schematic cross-sectional view taken along an open plane of the arm or a plane parallel thereto, showing an InAsP/InP-based buried semiconductor laser device. In this figure, the dimensional relationship, shape arrangement, etc. of each component are merely shown schematically to the extent that the present invention can be understood. Further, in the figure, only a portion is shown with hatching, and hatching in other portions is omitted.

In FIG. 2, 7 is an InP substrate as a base layer, and in this case, this substrate 7 also serves as a lower cladding layer. 8 is an active layer provided on this lower cladding layer 7;
Reference numeral 9 denotes an upper cladding layer provided on the active layer 8 and having a conductivity type opposite to that of the lower cladding layer. Each of these layers7.8
．． 9 constitutes a tuple heterostructure, and both side parts are removed from the surface of the upper cladding layer 9 to a part of the lower cladding layer 7 below the active layer 8, leaving the central part.
For example, it has a striped structure. Au x G is deposited on both sides of this stripe structure, that is, the double heterostructure, from the surface of the substrate, that is, the lower cladding layer 7 to the upper side, by metal organic vapor phase epitaxy along these both sides.
It is formed by growing ap-xAs 10 in a buried manner.

In this case, the central striped double heterostructure is
It may be formed by any epitaxial growth method such as wave phase, gas phase, organometallic vapor phase, or molecular beam. However, each layer forming this double heterostructure7.8.9
It is necessary to make the region of the buried layer 10 and the region of the buried layer 10 lattice mismatched so that the resistance at the interface between the inner regions is high, and the resistance of this buried layer 10 itself also needs to be high. There is. Therefore, in the present invention, material A sentence x Gap-xA
s as the material of the buried layer 10, this AJI
The lower cladding layer 7 is made of Ga1-xAs and is an InP substrate.
Secondly, this A pattern x Ga is grown by organometallic vapor phase epitaxy.
Make I-XAS non-doped.

Next, the operation will be explained. Electrons and holes injected into the active layer 8 through the upper and lower Clara 1ζ layers 9 and 7 recombine to emit light, causing stimulated emission. In the case shown in FIG. 2, the light is repeatedly reflected at the arm opening surface and oscillates as a laser in the Fabry-Perot mode. Also, this laser can be used as a DF
In the case of a B, DBI'l structure, this light oscillates as a laser using Bragg reflection.

In this case, since the InP end layers 9 and 7 have a lower refractive index than the active layer 8 in the vertical direction of this structure,
Light confinement is performed well, and in the lateral direction, A sentence x
Ga1nA whose refractive index of Ga + -xAs is active layer 8
By setting the value of X to be smaller than the refractive index of sP, it is possible to achieve good light confinement.

Next, we will discuss current confinement. AfLx GaI-x
As As has a much larger energy gap than InP and Ga InAsP, this Aix Gap-
Current does not easily flow into the xAs buried layer region 10 from the cladding layer 9.7 and the active layer 8. Also, Ill x G
Since the a r-xAs region 10 and the InP regions 7 and 9 are not lattice matched, high resistance occurs at the interface between the inner regions. Furthermore, by making A-pattern x Gap-x non-doped, a high-resistance layer can be easily selected, so that almost no current injected flows into the buried layer 10, but only in the double heterostructure region. Concentrate on and flow,
Increases luminous efficiency.

In this example, a semiconductor laser element has been described, but the end face of this element can also be operated as a light emitting diode without having an arm opening.

Further, the base layer mentioned above does not necessarily have to be the substrate itself, and may be another layer formed on the substrate, but in any case, it must be formed from a mixed crystal material of InP or Ga InAsP. is necessary.

Further, the conductivity types of these layers can be selected in an appropriate combination.

Furthermore, this laser may have a superlattice structure.

(Effects of the Invention) As is clear from the above description, according to the semiconductor light emitting device of the present invention, A or - Since a semi-insulating buried layer of xAs is provided and there is a lattice mismatch at the interface between the two, this buried layer works well as a current confinement layer, and the current confinement layer passes through this interface as in a conventional semiconductor light emitting device. No current leakage path is formed.

Therefore, there is no possibility that the output will be saturated during high injection, and there are advantages in that the luminous efficiency is improved and the oscillation threshold can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a sectional view for explaining the structure of a conventional embedded semiconductor light emitting device, and FIG. 2 is a schematic enlarged sectional view showing an embodiment of the semiconductor light emitting device of the present invention. 7... Base layer (substrate or lower cladding layer) 8... Active layer, 9... Upper cladding layer 10... Buried layer (
current confinement layer).

Claims (1)

[Claims] In a buried type semiconductor light emitting device having a buried layer on both sides of a double heterostructure, the buried layer is a semi-insulating semiconductor light-emitting device grown by organometallic vapor phase epitaxy on a base layer made of a mixed crystal of InP or GaInAsP. A9LX Gat-
A semiconductor light emitting device comprising ++As.