Sony Corporation

Mitsubishi Materials Corporation

Sony Chemicals Corporation

Mitsubishi Materials Silicon Corporation

Etsuo Morita

Hiroji Kawai

Hiroyuki Okuyama

Goshi Biwa

Akira Ishibashi

Masato Doi

Toyoharu Oohata

Shigetaka Tomiya

Yousuke Murakami

Masaharu Nagai

Kazushi Nakano

Satoshi Ito

Satoshi Matsumoto

Takeshi Matsushita

Hiroyuki Hasegawa

Masao Ikeda

Tadashi Yamamoto

Jun Suzuki

Takayuki Shingyouji

Tsuneo Nakajima

A crystal foundation having dislocations is used to obtain a crystal film of low dislocation density, a crystal substrate, and a semiconductor device. One side of a growth substrate () is provided with a crystal layer () with a buffer layer () in between. The crystal layer () has spaces (), () in an end of each threading dislocation Delongating from below. The threading dislocation Dis separated from the upper layer by the spaces (), (), so that each threading dislocation Dis blocked from propagating to the upper layer. When the displacement of the threading dislocation Dexpressed by Burgers vector is preserved to develop another dislocation, the spaces (), () vary the direction of its displacement. As a result, the upper layer above the spaces (), () turns crystalline with a low dislocation density.

Crystal film, crystal substrate, and semiconductor device

Crystal firm, crystal substrate, and semiconductor device

A crystal substrate and a crystal film of a III-V compound of the nitride system which are manufactured easily and have few dislocations as well as a method of manufacturing a crystal and a method of manufacturing a device with the use thereof are disclosed. On a basal body, formed in order are a base crystal layer of, for example, gallium nitride (GaN), a first mask pattern of, for example, silicon dioxide (SiO), an intermediate crystal layer of, for example, gallium nitride, a second mask pattern of, for example, silicon dioxide, and a top crystal layer of, for example, gallium nitride. The first and second mask patterns have stripes arranged at least in one direction at unequally spaced intervals. The stripes are different in pitch from pattern to pattern. Thus, the mask patterns at least partly overlie one another in the direction of the thickness of the crystal layers.

Method of manufacturing crystal of III-V compound of the nitride system, crystal substrate of III-V compound of the nitride system, crystal film of III-V compound of the nitride system, and method of manufacturing device

A crystal substrate and a crystal film of a III-V compound of the nitride system which have no defects in the surfaces. A method of manufacturing a crystal of a III-V compound of the nitride system, and a method of manufacturing a device. A base crystal layer is formed over a basal body. After etching the base crystal layer using a first mask pattern, an intermediate crystal layer is formed. After etching the intermediate crystal layer using a second mask pattern, a top crystal layer is formed. The crystal growth of the intermediate crystal layer starts at the walls of grooves formed by etching in the base crystal layer. This reduces the possibility that dislocations develop into the intermediate crystal layer. No dislocations occurring above the first mask pattern propagate through the top crystal layer since the dislocations are removed by etching using the second mask pattern.

To improve crystallographic property of a nitride III-V compound semiconductor layer grown on a sapphire substrate, a plurality of recesses are made on a major surface of the sapphire substrate, and the nitride III-V compound semiconductor layer is grown thereon. At least a part of the inner surface of each recess makes an angle not less than 10 degrees with respect to the major surface of the sapphire substrate. The recesses are buried with nitride III-V compound semiconductor crystal having a higher Al composition ratio than the nitride III-V compound semiconductor layer, such as AlGaN crystal whose Al composition ratio x is 0.2 or more, for example. Each recess has a depth not less than 25 nm and a width not less than 30 nm. The recesses may be made either upon thermal cleaning of the sapphire substrate or by using lithography and etching, thermal etching, or the like.

Method of crystallizing a nitride III-V compound semiconductor layer on a sapphire substrate

A semiconductor light emitting device includes a crystal layer formed on a substrate, the crystal layer having a tilt crystal plane tilted from the principal plane of the substrate, and a first conductive type layer, an active layer, and a second conductive type layer, which are formed on the crystal layer in such a manner as to extend within planes parallel to the tilt crystal plane, wherein the device has a shape formed by removing the apex and its vicinity of the stacked layer structure formed on the substrate. Such a semiconductor light emitting device is excellent in luminous efficiency even if the device has a three-dimensional device structure. The present invention also provides a method of fabricating the above semiconductor light emitting device.

Semiconductor light emitting device and fabrication method thereof

A base crystal layer is formed on the surface of a basal body by growing, e.g., GaN comprising a III-V compound by MOCVD and then the base crystal layer is etched. An intermediate crystal layer is formed by laterally growing GaN from windows formed in the base crystal layer by etching. In the intermediate crystal layer, an inner layer made of, e.g., AlGaN is formed. Then, the intermediate crystal layer is further etched and a top crystal layer is formed by laterally growing GaN from windows formed in the intermediate crystal layer by etching. An inner layer made of, e.g., AlGaN is formed in the top crystal layer. Development of dislocations is suppressed to some extent by the lateral growth when forming the intermediate crystal layer and the top crystal layer. Further, development of dislocations is suppressed by the inner layers.

METHOD OF MANUFACTURING CRYSTAL OF III-V COMPOUNDS OF THE NITRIDE SYSTEM, CRYSTAL SUBSTRATE OF III-V COMPOUNDS OF THE NITRIDE SYSTEM, CRYSTAL FILM OF III-V COMPOUNDS OF THE NITRIDE SYSTEM, AND METHOD OF MANUFACTURING DEVICE

There are provided a semiconductor substrate and a semiconductor laser using the semiconductor substrate which promises smooth and optically excellent cleaved surfaces and is suitable for fabricating semiconductor lasers using nitride III-V compound semiconductors. Using a semiconductor substrate, such as GaN substrate, having a major surface substantially normal to a &lcub;0001&rcub;-oriented face, e.g. &lcub;01-10&rcub;-oriented face or &lcub;11-20&rcub;-oriented face, or offset within &plusmn;5&deg; from these faces, nitride III-V compound semiconductor layers are epitaxially grown on the substrate to form a laser structure. To make cavity edges, the GaN substrate is cleaved together with the overlying III-V compound semiconductor layers along high-cleavable &lcub;0001&rcub;-oriented faces.

Semiconductor substrate made of a nitride III-V compound semiconductor having a wurtzite-structured crystal structure

To improve crystallographic property of a nitride III-V compound semiconductor layer grown on a sapphire substrate, a plurality of recesses are made on a major surface of the sapphire substrate, and the nitride III-V compound semiconductor layer is grown thereon. At least a part of the inner surface of each recess makes an angle not less than 10 degrees with respect to the major surface of the sapphire substrate. The recesses are buried with nitride III-V compound semiconductor crystal having a higher Al composition ratio than the nitride III-V compound semiconductor layer, such as Al,Ga,N crystal whose Al composition ratio x is 0.2 or more, for example. Each recess has a depth not less than 25 nm and a width not less than 30 nm. The recesses may be made either upon thermal cleaning of the sapphire substrate or by using lithography and etching, thermal etching, or the like.

Semiconductor device on a sapphire substrate

A semiconductor light emitting device is provided, which does not deteriorate in luminance, maintains a high reliability, permits more free choice of an adhesive, and promises effective extraction of light to the exterior even when it is bonded to a lead frame or other support with the adhesive in practical use. In a GaN light emitting diode, GaN compound semiconductor layers are stacked sequentially on a front surface of a sapphire substrate to form a light emitting diode structure, and a reflective film is formed on a rear surface. Alternatively, the GaN compound semiconductor layers forming the light emitting diode structure are selectively removed by etching to define an inverted mesa-shaped end surface, and the reflective film is formed on the end surface. Both the p-side electrode and the n-side electrode are formed on a common side of the substrate where the GaN compound semiconductor layers are formed.

Semiconductor light emitting device

A semiconductor device such as a semiconductor layer is formed of a compound semiconductor layer of III-V group such as GaN. In the case where the substrate has not any planes that are easy to cleave which coincides with an easy-to-cleave plane of a semiconductor layer grown on the substrate or the substrate easily succumbs to cleavage, then the semiconductor layer together with the substrate can be broken into chips in an easy-to-cleave plane. The cleaved surface of the semiconductor layer can be positively formed as an optically superior surface. A compound semiconductor layer 2 containing at least one of the elements {Ga, Al, In} and N is formed on the substrate 1. This compound semiconductor layer 2 has a pair of facets of {11-20} plane substantially perpendicular to the substrate 1.

Method for manufacture of cleaved light emitting semiconductor device

A semiconductor light emitting device ccomprises a first cladding layer, an active layer and a second cladding layer which are stacked on a semiconductor substrate. At least a part of the first cladding layer and the second cladding layer has a superlattice structure comprising II-VI compound semiconductor. Another semiconductor light emitting device comprises a first cladding layer, a first guide layer, an active layer, a second guide layer and a second cladding layer which are stacked on a semiconductor substrate. At least a part of the first cladding layer, the first guide layer, the second cladding layer and the second guide layer has a superlattice structure. Still anothr semiconductor light emitting device comprises a defect decomposing layer, a defect blocking layer, a first cladding layer, an active layer, a second cladding layer which are stacked on a semiconductor substrate. The defect decomposing layer and the defect blocking layer comprise a superlattice structure.

Growing community of inventors

Kanagawa, Japan

Etsuo Morita