Method of producing multi-wavelength semiconductor laser device

Abstract

Disclosed herein is a method for producing a multi-wavelength semiconductor laser device. The method comprises the steps of: forming first and second nitride epitaxial layers in parallel on a substrate for growth of a nitride single crystal; separating the first and second nitride epitaxial layers from the substrate; attaching the separated first and second nitride epitaxial layers to a first conductivity-type substrate; selectively removing the first and second nitride semiconductor epitaxial layers to expose a portion of the first conductivity-type substrate and to form first and second semiconductor laser structures, respectively; and forming a third semiconductor laser structure on the exposed portion of the first conductivity-type substrate.

Description

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to a multi-wavelength semiconductor laser device, and more particularly to a multi-wavelength semiconductor laser device capable of simultaneously or selectively oscillating laser light of three different wavelengths (e.g., 460 nm, 530 nm and 635 nm), and a method for producing the multi-wavelength semiconductor laser device. [0003] 2. Description of the Related Art [0004] In general, a semiconductor laser device is one that produces light amplified by stimulated emission of radiation. The light produced by the semiconductor laser device has a narrow frequency width (one of short-wavelength characteristics), superior directivity and high output. Due to these advantages, the semiconductor laser device is used as a light source for an optical pick-up apparatus of an optical disc system, such as a CD (compact disc) or DVD (digital video disc) player, as well as, is widely applied to a wide...

AI Technical Summary

Benefits of technology

[0021] In addition, the separation of the first and second nitride epitaxial layers from the substrate can be performed by irradiating the bottom surface of the substrate with laser light to lift-off the first and second nitride epitaxial layers. More preferably, the method of the present invention may further comprise the step of lapping the bottom surface of the substrate for growth of a nitride single crystal, before the laser irradiation, to decrease the thickness of the substrate.

[0028] In order to integrate the semiconductor laser structures composed of the respective epitaxial layers, which are grown under different conditions, into one chip, the multi-wavelength semiconductor laser device of the present invention is produced by forming the respective nitride epitaxial layers for the first and second semiconductor laser structures oscillating light of short wavelengths, separating the nitride epitaxial layers from each other, attaching the separated epitaxial layers to the first conductivity-type substrate, and forming the third semiconductor laser structure on the first conductivity-type substrate. Particularly, according to the method of the present invention, since the nitride epitaxial layers grown at a relatively high temperature are formed, separated from the substrate and attached to the first conductivity-type substrate, unwanted effects (diffusion of dopants, thermal shock, etc.) of the other layers during the subsequent epitaxial growth step are reduced. In addition, since etching is performed to form the semiconductor laser structures on the same substrate, a multi-wavelength semiconductor laser device in which the respective laser structures are highly aligned, can be produced.

Problems solved by technology

As explained earlier in FIGS. 1a to 1g, the conventional method is limited to the two-wavelength (650 nm and 780 nm) semiconductor laser device, and thus cannot be applied to a three-wavelength (further including light of a short wavelength) semiconductor laser device.

In this connection, there is a problem that since GaN-based epitaxial layers are particularly required to produce a semiconductor laser device oscillating light at wavelengths of 460 nm and 530 nm, they cannot be formed on the same substrate, together with a semiconductor laser structure oscillating light at a wavelength of 635 nm.

More specifically, since there is a large difference in the lattice constant between the AlGaInP epitaxial layer (about 5.6 Å) and the GaN epitaxial layer (about 3.2 Å) for the semiconductor laser structure oscillating light at a wavelength of 635 nm, it is difficult to grow the AlGaInP and GaN epitaxial layers on the same substrate.

Consequently, a multi-wavelength semiconductor laser device oscillating three-color light, for example, at wavelengths of 460 nm, 530 nm and 635 nm, cannot be substantially produced by the conventional method for producing a two-wavelength semiconductor laser device.

Images