JPH0821757B2 - Semiconductor light emitting device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor light emitting device, and particularly to a structure capable of inexpensively providing an InGaAlP-based light emitting element represented by a visible light semiconductor laser.

2. Description of the Related Art AlGaAs or InGaAsP semiconductor lasers have been used as conventional semiconductor lasers, and GaAs or InP has been used as a substrate. Since a semiconductor laser has a high photo-electric field due to high current injection, high electric-to-light conversion efficiency is required, and a high-quality thin film multilayer epitaxial growth technique with few impurities and defects is required. Therefore, the substrate crystal needs to have few defects and good crystallinity, and further, the lattice mismatch of the layer grown thereon needs to be 10 ⁻³ or less. However, due to advances in crystal growth technology, GaAs single crystals have recently been obtained on a Si substrate via a buffer layer that alleviates irregularities in the lattice constant, and the oscillation of an AlGaAs laser can be confirmed. Typical low-temperature grown GaAs layers and superlattice layers such as GaP and GaAs have been tried as buffer layers in the epitaxial growth of GaAs layers on Si (Electronics Letters 20.No.22.916). (1984)).

Problems to be Solved by the Invention However, the GaAs crystal thus obtained also has many crystal defects, and a lattice pattern is generated due to lattice irregularity or a difference in expansion coefficient. Not up to.

Therefore, the present invention provides a method for obtaining a good quality crystal growth film on a Si substrate, and further provides a semiconductor laser and a light emitting diode using this good quality crystal layer structure.

Means for Solving the Problems The present invention is intended to obtain a good crystal film of InGaP, InGaAlP, InGaAsP, etc. by interposing an In _x Ga _1-x P layer on a Si substrate. . That is, the first layer containing In _x Ga _1-x P (0x1) is provided on the Si substrate, and the AlGaInP, InGaP or InGaAsP layer is used as the carrier recombination active region for light emission on the first layer. A semiconductor light-emitting device having two layers, further comprising:
_x Ga _1-x P The first layer is a layer having a composition gradient in which the composition x is sequentially changed, or In _x Ga _1-x P, In _y Ga _(1-y) P (0y
It is intended to obtain a good light emitting device by improving the crystallinity of the light emitting region formed on the layer by forming a multi-layered stack of a plurality of compositions such that 1, y ≠ x).

Such a layer is formed by a growth method using an organic metal, a chloride method, a vapor phase growth method such as an MBE method.

Action The present invention is a layered growth of different materials such as Si single crystal and InGaP, AlGaInP, InGaAsP, and yet, the lattice constant is greatly different, the layered single crystal growth of the material having a different thermal expansion coefficient,
It can be performed in a state of good crystallinity.

As this method, a lattice relaxation layer called InGaP is formed on Si to improve the crystallinity of the growth layer thereon, and is further applied to a light emitting device.

Example FIG. 1 shows a sectional structure of an example of the semiconductor light emitting device of the present invention. In the figure, 1 is an n-type Si substrate, 2 is a n-type In _x Ga _1-x P graded layer (lattice relaxation layer), 3 and 5 are n-type And p-type
AlGaInP clad layer, 4 In _x Ga _1-x P active layer, 6 p-type Al
GaInP buried layer, 7 is an n-type AlGaInP buried layer. 8 and 9 are p-type and n-type electrodes.

Due to the forward bias applied to the 8 and 9 electrodes, a current flows through the layers 3, 4 and 5, and electrons and holes recombine in the active region 4 to emit light. Part of the emitted light is confined in the 3,5,6,7 layer, which has a lower refractive index than the active region,
FIG. 1 Emit in a direction perpendicular to the sectional structure.

Each composition of the structure in this example is shown in FIG. Figure 2 shows the phase diagram of the InP-GaP-InAs-GaAs quaternary system and AlP-
The phase diagram of an InP-GaP ternary system is shown, and the composition with a constant lattice constant in an Example is shown by CBADE.

This device is grown by epitaxial growth on a (100) Si substrate by metalorganic vapor phase epitaxy. First, the graded layer 2 formed on the Si substrate is shown in FIG.
The composition was sequentially shifted from the P composition toward the composition A point, and compositions 3 and 5 were compositions at the point B in which the lattice constant was the same as that at the point A. Further, 4 is an InGaAs layer having a composition of point A. Layers 6 and 7 are A with B point or C point composition
lGaInP or AlInP layer. With such a structure, a light emitting device having a center wavelength of 620 nm could be received. Furthermore, a semiconductor laser can be obtained by forming a resonator by cleaving the re-facet of this device.

When the active layer has a composition of B point and the 3, 5, 6, 7 layers have a C point, light having a shorter wavelength can be obtained.

As the second embodiment, an InGaAsP light emitting device and a laser can be obtained with the same structure as the first embodiment. It is the same that the InGaP graded layer is formed on the Si substrate as No. 1 to alleviate the mismatch of the lattice constant, but the active region of No. 3 has the composition at point D in FIG. The composition is point A. By doing so, light having a wavelength of about 600 nm can be obtained even in the InGaAsP active layer.

Change the lattice constant of each epitaxial layer on the Si substrate to the third
Shown in the figure. In the above example, the lattice constant is changed by shifting the composition of the two layers to the InP side in sequence, but instead of the graded change, the GaP, InGaP composition or the InGaP superlattice with a different composition can be used to form a layer on it. A good quality epitaxial film can be obtained.

FIG. 4 shows an example in which the lattice relaxation layer 2 in FIG. 1 has a superlattice structure. About 50 Å of GaP layer 11 is formed on Si substrate 1, and about 5 InGaP layer 12 of point A composition in FIG. 2 is formed thereon.
0Å form. In addition, each of these 10 turns back as well
Form the layers. On the lattice relaxation layer 2 thus formed, 3,4,5 layers are epitaxially grown in the same manner as in FIG. 1 to form a laser. It is possible to form a good single crystal epitaxial film even with crystals on the lattice relaxation layer having a superlattice structure, and laser oscillation is realized.

Further, not only GaP / InGaP as the relaxation lattice but also GaP as the first layer and a superlattice having a different composition of InGaP can obtain a similar good quality film.

Although the embodiment has been described with reference to the semiconductor laser, it goes without saying that it can be applied to a light emitting diode.

EFFECTS OF THE INVENTION As described above, according to the present invention, a good epitaxial layer is formed on a Si substrate by adopting an InP-GaP system lattice relaxation layer and having a graded composition change or a superlattice structure. It has become possible to form. Thus, by introducing the InP-GaP-based lattice relaxation layer, (1) it becomes possible to form a good AlP-GaP-InP-based epitaxial layer without introducing As-based.

It is a reduction of the control component in the growth, and the growth condition becomes simple.

(2) It becomes possible to grow an AlGaInP, InGaP, InGaAsP layer having a wide composition range having a lattice constant different from that of Si on a Si substrate.

(3) It becomes possible to construct a light emitting diode and a semiconductor laser using InGaP, AlGaInP, InGaAsP as an active layer on a Si substrate.

[Brief description of drawings]

FIG. 1 is a sectional view of a light emitting device according to an embodiment of the present invention, FIG. 2 is an InGaAsP and AlGaInP system phase diagram, FIG. 3 is a characteristic diagram showing each growth layer and its lattice constant change, and FIG. 4 is the present invention. FIG. 6 is a cross-sectional view of a superlattice type lattice relaxation layer of another example. 1 ... Si substrate, 2 ... n-type InGaP graded layer, 4 ...
… InGaP active layer, 8,9 …… electrode.

Front page continuation (72) Inventor Jun Otani 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Tomoaki Uno 1006 Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd. (72) Invention Person Hiroaki Yamamoto 1006 Kadoma, Kadoma-shi, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) Reference JP-A-63-155781 (JP, A)

Claims (2)

[Claims] 1. A first layer containing In _X Ga _1-X P (0 ≦ x ≦ 1) is formed on a Si substrate, and an AlGaInP layer and InGaP are formed on the first layer.
A semiconductor light emitting device having a second layer having a layer or an InGaAsP layer as a carrier recombination active region for light emission, wherein the first layer containing In _X Ga _{1 -X} P has a composition x A layer with a composition gradient that changes in sequence, or In _X Ga
_A semiconductor light emitting device, which is a layer formed by a multi-layer stack of a plurality of compositions of _1-X P, In _Y Ga _1-Y P (0 ≦ y ≦ 1, y ≠ x). 2. The semiconductor light emitting device according to claim 1, wherein the In _X Ga _1-X P layer is composed of a layer grown from a vapor phase containing each element.