Matsushita Electric Industrial Co., Ltd.

Matsushita Electronics Corporation

Morio Inoue

Kunio Itoh

Tamotsu Uragaki

Kunihiko Asahi

Yukio Takashima

Susumu Koike

Gota Kano

Genshu Fuse

Hitoo Iwasa

Shotaro Umebachi

Haruyoshi Yamanaka

Shingi Fujii

Shohei Fujiwara

Yoshimitsu Okuda

Tohru Ohkuma

Crystal evaluation apparatus is disclosed which includes a cell region having an anode and a cathode, a reservoir tank for supplying of an aqueous solution for forming an anodic oxide film in the cell region, a reservoir tank for supplying of an aqueous solution for removing the anodic oxide film and a scanning microprobe microscope having a scanning microprobe, installed inside the cell region. A crystal evaluation method is also disclosed which contains anodic oxidation on a semiconductor substrate, removal of an anodic oxide film developed. The semiconductor substrate is observed with a scanning probe microscope having a scanning microprobe. The oxide film is formed on the semiconductor substrate by the anodic oxidation method and then removed by a mixture of hydrofluoric acid and ammonium fluoride. The anodic oxidation method exerts no or little physical impact on the substrate. The hydrofluoric acid and ammonium fluoride mixture removes selectively only the oxide film so that secondary ion implantation defects are exposed to a surface of the substrate. The shape or configuration of the secondary ion implantation defects is observed with an atomic force microscope having a high resolution on the order of nano meter. Therefore, the shape of the defects on the order of nano meter may be observed. In addition, the distribution of impurity concentration over the surface of the substrate may be measured very accurately.

Crystal evaluation apparatus and crystal evaluation method

Disclosed is a method of forming a resist pattern by exposing a novolak type positive photoresist to ultraviolet light in a pattern, irradiating the entire surface with far ultraviolet light with wavelength of 200 to 320 nm in an atmosphere with inert gas partial pressure ratio of 90% or more, and developing it. According to this method, a specific gradient of solubility in developing solution becoming higher from the surface toward the depthwise direction is provided, and a contrast value of twice as high as in the conventional method can be obtained, and a resist pattern of high aspect ratio is formed.

Forming method of resist pattern

A method for growing semiconductor epitaxial layers for manufacturing semiconductor devices such as light emitting diodes, characterized by

Method for growing semiconductor epitaxial layers

A semiconductor laser is made by sequential liquid-phase epitaxial growths on an n-type GaAs substrate, thereby sequentially forming

Heterostructure semiconductor device having a top layer etched to form a

When a highly resistive GaAs film doped with a metal impurity such as Fe, Ni or Cr is epitaxially grown from the vapor phase, a metallocene of this metal impurity such as Fe(C.sub.5 H.sub.5).sub.2, Cr(C.sub.5 H.sub.5).sub.2 or Ni(C.sub.5 H.sub.5).sub.2 or a derivative of this metallocene is employed as a starting material of this impurity. Even at room temperature or a temperature lower than room temperature a metallocene or a derivative thereof has such a high vapor pressure as to permit the epitaxial growth of a semi-insulating film so that heating of a line for feeding an impurity into a reaction tube may be eliminated and consequently an epitaxial system may be much simplified. Furthermore introduction of the impurity into the reaction tube may be instantaneously started or stopped by opening or closing a stop valve inserted into the feed line so that the impurity distribution may be sharply changed from one semi-insulating epitaxially grown film to another.

Method for growing semiconductor crystal

In order to decrease threshold current of a semiconductor laser, and to obtain a single mode lasing suitable for use in light-communication, the semiconductor laser is formed in stripe type in which the light-emitting (i.e., active) layer and neighboring layers are formed in mesa-etched stripe type and low impurity-concentration (i.e., high resistivity) layers of GaAs, GaAsP or GaAlAs are situated to contact the mesa-etched side faces of the stripe-shaped part on the semiconductor device by vapor phase growth, vacuum deposition, sputtering, or molecular beam deposition. Since the wafer temperature can be kept fairly low (e.g. 400.degree.-700.degree. C.) in comparison with that (about 950.degree. C.) in a liquid phase growth, the stress introduced during the deposition is smaller than that in a liquid phase growth.

Method of making a semiconductor light-emitting device utilizing

A mesa region of a stripe geometry is formed by mesa-etching a surface of a GaAs crystal substrate, forming a crystal layer of higher resistivity than the abovementioned crystal substrate so as to fill the abovementioned mesa-etched recesses in a manner that the stripe shaped mesa region is buried in the higher resistivity regions making top faces of the mesa region and the higher resistivity regions flush with each other, then forming, on the abovementioned flush surface, several epitaxial growth regions of semiconductor crystal including a light emitting region, for instance, an active region for lasing, subsequently forming contact isolation region having an opening of the stripe geometry corresponding to and above said mesa region. The current flow in the active region is confined in a narrow stripe region.

Solidstate light-emitting device

In a semiconductor laser with light guide, wherein an active region to form the Fabry-Perot cavity is formed in a mesa part on a semiconductor substrate and mixed crystal semiconductor parts formed to fill the mesa-etched parts constitute light guides. The improvement is that a crystal semiconductor of the active region has the composition of Ga.sub.1-x Al.sub.x As (0.ltoreq.x&lt;1) and a mixed crystal of the light guide has the composition of GaAs.sub.1-y P.sub.y (0&lt;y&lt;1) or Ga.sub.1-z Al.sub.z As (0&lt;x&lt;z&lt;1) of sufficiently high (for instance, 10.sup.4 .OMEGA.cm) specific resistivity with respect to that of the active region, the value of y or z being selected to be smallest at a depth of the light guide where the lasing light is incident, and the energy gap of the mixed crystal part being selected to be larger than that of said active region, so that light loss in the light guide is decreased.

Semiconductor laser with light guide

When gallium phosphide is etched with hot phosphoric acid from the surface of a crystal having a (1 1 1) plane, the etched surface becomes a flat and smooth plane inclined at an angle of 45.degree. to 55.degree. to the (1 1 1) plane. Accordingly, when an electroluminescent diode is manufactured by forming a p-n junction on a gallium phosphide crystal having a (1 1 1) plane and etching the crystal with a hot concentrated phosphoric acid etching solution to form a mesa structure, the side faces of the resulting crystal becomes inclined to the plane of the junction at an angle of nearly 45.degree. so that the visible rays generated in the p-n junction are totally reflected on the side faces, thus markedly increasing the intensity of emitted rays in the direction of the optical axis perpendicular to the principal plane of the p-n junction.

Process for manufacturing a gallium phosphide electroluminescent device

The invention discloses a heterojunction Type GaAs field-effect transistor of the type in which a channel region consists of an n-type GaAs layer with a higher mobility and a gate region consists of a p-type Ga.sub.1-y Al.sub.y As layer which is grown heteroepitaxially. The length of the gate is of the order of microns, and a gate, source and drain electrodes are self-aligned. The gate region is etched in the form of a mushroom with the use of an etchant which etched the GaAlAs layer and the Ga-As layer at different etching rates so that the gate, source and drain electrodes may be formed by only one vacuum deposition of a metal such as aluminum.

Junction gate type GaAs field-effect transistor and method of forming

Double-hetero-structure injection laser can be improved to have low threshold current in room-temperature continuous-wave operation. The improvement is obtained in one case wherein an n-type Ga.sub.1.sub.-y Al.sub.y As region (1.gtoreq.y&gt;0) is first formed, a Ga.sub.1.sub.-z In.sub.z As is grown thereon as an active region and a p-type Ga.sub.1.sub.-y Al.sub.y As region is then formed on the active region and the value of z is so selected as to make the lattice constants of the active region smaller than those of the first and third regions.

Semiconductor laser

A double-heterostructure injection laser can be improved to have a low threshold current. The improvement is obtained when the active region of GaAs or Ga.sub.l-y Al.sub.y As consists of several component layers wherein the central layer has the highest carrier concentrations and the layers on both sides of the central layer have lower carrier concentrations and the farther the outer layers are apart from the central layer, the lower are their carrier concentrations. By forming the active region in this manner, the light generated in the active region is well confined in the region without undesirable leaking, resulting in a considerable lowering of the threshold current.

Growing community of inventors

Takatsuki, Japan

Morio Inoue