Research Development Corporation of Japan

Other

Mitsubishi Materials Corporation

Mitsubishi Metal Corporation

Zaidan Hojin Handotai Kenkyu Shinkokai

Koichi Sassa

Kenji Tomizawa

Keiji Shirata

Yasushi Shimanuki

Mino Green

Stuart A Solin

Takashi Atami

Richard A Stradling

Shin Tsuchiya

Nobuyuki Uchida

Taizo Ohmura

Mesoscopic magnetic field sensors which can detect weak magnetic fields (typically 0.05 Tesla) over areas as small as tens of thousands of square nanometers (e.g. 40 nm&times;400 nm). The combination of enhanced magneto-resistance in an inhomogeneous high mobility semiconductor, having special electrode arrangements, with the use of island lithography, enables the production of special semiconductor/metal nano-composite structures, and has made possible the fabrication of an entirely new type of magnetic field sensor which exhibits very superior magneto-resistive behavior.

Mesoscopic non-magnetic semiconductor magnetoresistive sensors fabricated with island lithography

Method and apparatus for producing compound semiconductor single crystal

The present invention relates to a method and apparatus for mono-crystalline growth of a dissociative compound semiconductor. The method, which is based on the Czochralski method, includes the following steps. First, a first volatile component material and second material of the dissociative compound semiconductor are prepared. The first material is placed on the bottom of an inner air-tight vessel which is contained in the outer air-tight vessel. The second material is contained in a crucible in the inner vessel. The crucible is supported by a lower shaft extending from the inside to the outside of the inner vessel. The first material is, next, heated for evaporating so as to react with the second material in the crucible. Therefore, the dissociative compound semiconductor is synthesized in the crucible. Then, a single crystal is pulled up from the melt by an upper shaft. The upper shaft extends from inside to outside of the inner vessel, thereby the single crystal is grown. The improvement is that the pulling-up process includes the steps of, after the heating step: measuring the weight of the melt in the crucible, the weight of the melt being influenced by a difference between the interior pressure of the inner vessel and a pressure outside of the inner vessel; correcting the measured weight of the melt for the error due to the pressure difference, thereby obtaining an accurate data of the weight of the melt; and controlling at least one of a composition and a diameter of the growing crystal on the basis of the weight data of the melt.

Method for monocrystaline growth of dissociative compound semiconductors

In a single-crystal growth method disclosed herein, a melt is first prepared in a container having a cylindrical wall. The container is such that at least the inner peripheral surface of the cylindrical wall is formed of a material which is not wettable to the melt. A seed is then immersed in the melt and a single crystal rod formed on the seed is pulled in such a manner as to be coaxial with the cylindrical wall. The distance between the single crystal rod and the inner peripheral surface is set to a prescribed value G, so that the melt adjacent to the inner peripheral surface is formed into a prescribed meniscus shape. The temperature distribution at the melt surface is controlled to maintain the meniscus shape between the single crystal rod and the inner peripheral surface at an equilibrium state to thereby control the diameter of the single crystal rod.

Method for growing single crystal

The present invention relates to a method and apparatus for mono-crystalline growth of a dissociative compound semiconductor. The method, which is based on the Czochralski method, includes the following steps. First, a first volatile component material and second material of the dissociative compound semiconductor are prepared. The first material is placed on the bottom of an inner air-tight vessel which is contained in an outer air-tight vessel. The second material is contained in a crucible supported in the inner vessel by a lower shaft extending from the inside to the outside of the inner vessel. The first material is, next, heated for evaporating so as to react with the second material. Therefore, the dissociative compound semiconductor is synthesized in the crucible. Then, temperature of a furnace installed on the inner vessel is adjusted so that the pressure of the gas of the first volatile component material in the inner vessel is controlled. A single crystal is pulled up from the melt by an upper shaft extending from inside to outside of the inner vessel, thereby the single crystal is grown. The improvement is that the pulling-up step includes the steps of: measuring the weight of the growing crystal, the weight influenced by a difference between the interior pressure of the inner vessel and a pressure outside of the inner vessel; correcting the measured weight of the crystal for the error due to the pressure difference, thereby obtaining an accurate estimate of the weight of the crystal; and controlling a diameter of the growing crystal on the basis of the weight estimate of the crystal.

Method for monocrystalline growth of dissociative compound semiconductors

A method for growing single crystals of a dissociative compound semiconductor which are pulled in an atmosphere of a gas of a volatile component of the dissociative compound filled in an inner chamber sealed within a growth apparatus is provided wherein the space of the inner chamber is divided into different parts by means of partition wall, which is disposed in the inner chamber and the lower part of which is immersed in a melt contained in a crucible, thereby high quality single crystals with a correct stoichiometric composition can be grown under the constant conditions of temperature and pressure without detrimental effects due to thermal convection in the crystal growth region and the melt. The partition wall may be made either of a monolithic structure or a composite structure capable of being divided into two parts, an upper member and a lower member like a float, the upper part of the lower member is vertically movably inserted into upper member.

Method for growing single crystals of dissociative compound semiconductor

An apparatus for pulling single crystals of dissociative compounds, with a volatile component gas sealed in a growth chamber at a controlled pressure thereof, is disclosed, wherein the chamber is made of one or more materials selected from the group consisting of ceramics, gas-tight carbon, heat-resistant metallic materials, ceramic-coated carbon and ceramic-coated heat-resistant metallic materials, the chamber can be divided, with a structure of the divided portion of the chamber capable of being sealed by making use of a sealing material with a pressure exerted on the seal, and an optical window is disposed in the chamber through which the growing state of the crystal in the chamber can be observed.

Apparatus for growing single crystals of dissociative compounds

The present invention provides a method for growing single crystals of a dissociative compound by pulling with a volatile component gas of the dissociative compound sealed at a controlled pressure in a heated growth chamber in which the single crystals are pulled, wherein a partition pipe having a lower density than the density of melt of the dissociative compound is disposed so as to immerse its lower end in the melt and the melt is covered with B.sub.2 O.sub.3 at either one of the inside or outside of the partition pipe. The method of the present invention enables the precise, appropriate control of the melt composition during the course of growing and thereby provides single crystals free from any detrimental contamination and undesirable dislocation problems. The thus obtained crystals are especially desirable for use as substrates for high speed and/or optical devices, because of their excellent semi-insulating properties.

Growing community of inventors

Omiya, Japan

Koichi Sassa