Semiconductor laser, semiconductor device and nitride series III-V group compound substrate, as well as manufacturing method thereof

Abstract

A semiconductor laser, a semiconductor device and a nitride series III-V group compound substrate capable of obtaining a crystal growth layer with less fluctuation of the crystallographic axes and capable of improving the device characteristics, as well as a manufacturing method therefor are provided. The semiconductor laser comprises, on one surface of a substrate used for growing, a plurality of spaced apart seed crystal layers and an n-side contact layer having a lateral growing region which is grown on the basis of the plurality of seed crystal layers. The seed crystal layer is formed in that a product of width w1 (unit: μm) at the boundary thereof relative to the n-side contact layer along the arranging direction A and a thickness t1 (unit: μm) along the direction of laminating the n-side contact layer is 15 or less. This can decrease the fluctuation of the crystallographic axes in the n-side contact layer. Accordingly, crystallinity of the semiconductor layer including from n-type clad layer to a p-side contact layer laminated on the n-side contact layer is improved. A semiconductor laser and a semiconductor device capable of decreasing dislocation density and improving device characteristics, as well as a manufacturing method therefor are provided. A semiconductor layer comprising a nitride series III-V group compound semiconductor is laminated on a substrate 11 comprising an n-type GaN. Protruded seed crystal portions are formed and a growth suppression layer having an opening corresponding to the seed crystal portion is disposed to the substrate. The semiconductor layer grows on the basis of the seed crystal portion and has a lateral growing region of low dislocation density. When a current injection region is disposed corresponding to the lateral growing region, the light emission efficiency can be improved. Further, when the growth suppression layer is provided with a function of reflecting or absorbing light generated in the semiconductor layer, it is possible to prevent leakage of light or intrusion of stray light from the substrate to suppress generation of noises.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention concerns a semiconductor device having a seed crystal layer and a crystal growth layer grown on the basis of the seed crystal layer, a semiconductor laser and a nitride series III-V group compound substrate, as well as a manufacturing method thereof. This invention also relates to a semiconductor laser and a semiconductor device having a substrate comprising a nitride series III-V group compound and a semiconductor layer comprising a nitride series III-V group compound grown on the basis of the substrate as well as a manufacturing method thereof. 2. Description of the Related Art Nitride series III-V group compound semiconductors such as GaN, AlGaN mixed crystals or GaInN mixed crystals are direct transition semiconductor materials and have a feature in which the forbidden band gap ranges from 1.9 eV to 6.2 eV. Accordingly, the nitride series III-V group compound semiconductors can provide emission from a visi...

AI Technical Summary

Benefits of technology

This invention has been accomplished in view of the foregoing problems and intends to provide a semiconductor laser, a semiconductor device and a nitride series III-V group compound substrate capable of obtaining a crystal growth layer with less fluctuation of the crystallographic axes and capable of improving the device characteristics, as well as a manufacturing method therefor.

This invention also intends to provide a semiconductor laser and a semiconductor device capable of decreasing the dislocation density and improving the device characteristics, as well as a manufacturing methods therefor.

In another semiconductor laser or another semiconductor device according to this invention, the seed crystal layer is adapted in that the product of the width (unit: μm) at the boundary of the seed crystal layer relative to the crystal growth layer along the direction perpendicular to the extending direction thereof and a thickness (unit: μm) along the direction of laminating the crystal growth layer is 15 or less. Accordingly, fluctuation of the crystallographic axes in the crystal growth layer is decreased.

In the method of manufacturing the semiconductor laser, the method of manufacturing the semiconductor device or the method of manufacturing the nitride series III-V group compound substrate according to this invention, the crystal growth layer is grown on the basis of a plurality of seed crystal layers formed in that a product of the width (unit: μm) at the upper surface on the growing side along the direction of arrangement and a thickness (unit: μm) along the growing direction is 15 or less. Accordingly, fluctuation of the crystallographic axes in the crystal growth layer is decreased.

In the semiconductor laser and the semiconductor device according to this invention, since the semiconductor layer is grown on the basis of the seed crystal portions of the substrate, dislocation density in the semiconductor layer is decreased.

Problems solved by technology

However, since lattice mismatching or difference of heat expansion coefficient is large between sapphire or silicon carbide and the nitride series III-V group compound semiconductor, lattice defects such as dislocations are formed for moderating strains in the nitride series III-V group compound semiconductor layer.

However, the first method involves a problem that defects are increased by the dislocation generated in the crystal growth layer if there is fluctuation of the crystallographic axes in the crystal growth layer.

Further, it has a problem that the dislocation tends to propagate while extending in the lateral direction.

Further, the second method involves a problem that the dislocation density is as high as about 1×108 cm−2 to 1×1011 cm−2 since the substrate comprising the nitride series III-V group compound is prepared, for example, by growing on a substrate comprising sapphire or the like.

Accordingly, the dislocation density also increases in the layer of the nitride series III-V group compound semiconductor to be grown on the substrate, failing to improve the device characteristics.

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