Toyoda Gosei Co., Ltd.

Akira Kojima

Masayoshi Koike

Seiji Nagai

Yuta Tezen

Toshio Hiramatsu

Toshiya Uemura

Shiro Yamazaki

Shiro Yamasaki

Kazuyoshi Tomita

Masanobu Ando

Takayoshi Yajima

Koji Kaga

A method of making a light emitting element, the light emitting element with a semiconductor layer represented by: AlInGaN (0&#x2266;X&#x2266;1, 0&#x2266;Y&#x2266;1, 0&#x2266;X+Y&#x2266;1), has the step of wet-etching a surface of the semiconductor layer by using an etching solution to have a roughened surface on the semiconductor layer. The wet-etching is conducted without irradiating the surface of the semiconductor layer with a light with a wavelength region corresponding to energy higher than bandgap energy of the semiconductor layer.

Method of making a light emitting element

A light-emitting semiconductor device provides an active layer which comprises thirteen (13) layers that includes six (6) pairs of quantum barrier layers made of AlInN and quantum well layers made of AlInN, which are laminated together alternately. The semiconductor device may also comprise a quantum well layer having a high composition ratio of indium (In). Forming the quantum barrier layer and the quantum well layer to have a high composition ratio of indium (In) increases the lattice constant of the active layer of the semiconductor device.

Light-emitting device using group III nitride group compound semiconductor

A seed layer as a laminate of a GaN layer (second seed layer) and an AlN buffer layer (first seed layer) is formed on a sapphire substrate. A front surface thereof is etched in the form of stripes with a stripe width (seed width) of about 5 &#x3bc;m, a wing width of about 15 &#x3bc;m and a depth of about 0.5 &#x3bc;m. As a result, mesa portions each shaped like nearly a rectangle in sectional view are formed. Non-etched portions each having the seed multilayer as its flat top portion are arranged at arrangement intervals of L&#x2248;20 &#x3bc;m. Part of the sapphire substrate is exposed in trough portions of wings. The ratio S/W of the seed width to the wing width is preferably selected to be in a range of from about &#x2153; to about &#x2155;. Then, a semiconductor crystal A is grown to obtain a thickness of not smaller than 50 &#x3bc;m. The semiconductor crystal is separated from the starting substrate to thereby obtain a high-quality single crystal independent of the starting substrate. When a halide vapor phase epitaxy method is used in the condition that the V/III ratio is selected to be in a range of from 30 to 80, both inclusively, a semiconductor crystal free from cracks can be obtained.

Method for producing semiconductor crystal

By using a mask , a first Group III nitride compound semiconductor layer is etched, to thereby form an island-like structure such as a dot-like, striped-shaped, or grid-like structure, so as to provide a trench/post. Thus, without removing the mask formed on a top surface of the upper layer of the post, a second Group III nitride compound layer can be epitaxially grown, vertically and laterally, with a sidewall/sidewalls of the trench serving as a nucleus, to thereby bury the trench and also grow the layer in the vertical direction. The second Group III nitride compound layer does not grow epitaxially on the mask . In this case, propagation of threading dislocations contained in the first Group III nitride compound semiconductor layer can be prevented in the upper portion of the second Group III nitride compound semiconductor that is formed through lateral epitaxial growth and a region having less threading dislocations can be formed in the buried portion of the trench.

Method for producing group III nitride compound semiconductor and group III nitride compound semiconductor device

A semiconductor laser comprises a sapphire substrate , an AlN buffer layer , Si-doped GaN n-layer , Si-doped Al Ga N n-cladding layer , Si-doped GaN n-guide layer , an active layer having multiple quantum well (MQW) structure in which about 35 &angst; in thickness of GaN barrier layer and about 35 &angst; in thickness of Ga In N well layer are laminated alternately, Mg-doped GaN p-guide layer , Mg-doped Al Ga N p-cladding layer , and Mg-doped GaN p-contact layer are formed successively thereon. A ridged hole injection part B which contacts to a ridged resonator part A is formed to have the same width as the width w of an Ni electrode . Holes transmitted from the Ni electrode are injected to the active layer with high current density, and electric current threshold for laser oscillation can be decreased. Electric current threshold can be improved more effectively by forming also the p-guide layer to have the same width as the width w of the Ni electrode

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Aichi, Japan

Akira Kojima