Kabushiki Kaisha Kobe Seiko Sho

Kobe Steel Usa, Inc.

Kozo Nishimura

Koji Kobashi

Koichi Miyata

Kimitsugu Saito

Takeshi Tachibana

Shigeaki Miyauchi

Kazuo Kumagai

Rie Kato

Hisashi Koyama

Yoshihiro Yokota

Yoshihiro Shintani

Brian Rhys Stoner

Kazushi Hayashi

Hiroyuki Takamatsu

Hiroyuki Tachibana

Yoshiro Nishimoto

Norio Suzuki

Yutaka Kawata

Takuya Kusaka

Yasuhide Nakai

Yoshio Kawate

Kiyotaka Ishibashi

Akimitsu Nakaue

Yoshihiko Onishi

Takayoshi Inoue

Yasuji Yoneda

Rie Nakamura

Hiroshi Kajikawa

Shigeki Tojyo

Rie Katoh

Hisahi Koyama

Shinichi Imaoka

Disclosed is a method of forming electrodes on diamond comprising the steps of: forming a mask pattern on diamond or diamond film; performing a treatment of the diamond surface by a plasma of inert gases; forming an electrode film on the whole surface of the specimen; and removing the mask, thereby forming a specified pattern of the electrodes. By this method, it is possible to form electrodes having high adhesion to diamond and diamond film for electronic devices.

Method for forming electrode on diamond for electronic devices

A method is related to grow monocrystalline diamond films by chemical vapor deposition on large area at low cost. The substrate materials are either bulk single crystals of Pt or its alloys, or thin films of those materials deposited on suitable supporting materials. The surfaces of those substrates must be either (111) or (001), or must have domain structures consisting of (111) or (001) crystal surfaces. Those surfaces can be inclined within .+-.10 degree angles from (111) or (001). In order to increase the nucleation density of diamond, the substrate surface can be scratched by buff and/or ultrasonic polishing, or carbon implanted. Monocrystalline diamond films can be grown even though the substrate surfaces have been roughened. Plasma cleaning of substrate surfaces and annealing of Pt or its alloy films are effective in growing high quality monocrystalline diamond films.

Methods for manufacturing monocrystalline diamond films

Disclosed is planar and vertical cold cathode emitter elements including an semiconducting diamond emitter portion having a high thermal resistance and a high breakdown voltage, thereby suppressing the deterioration of the electron emission characteristics and enabling the operation with a high electric power.

Cold cathode emitter element

A method is presented to manufacture substrates for growing monocrystalline diamond films by chemical vapor deposition (CVD) on large area at low cost. The substrate materials are either Pt or its alloys, which have been subject to a single or multiple cycle of cleaning, roller press, and high temperature annealing processes to make the thickness of the substrate materials to 0.5 mm or less, or most preferably to 0.2 mm or less, so that either (111) crystal surfaces or inclined crystal surfaces with angular deviations within .+-.10 degrees from (111), or both, appear on the entire surfaces or at least part of the surfaces of the substrates. The annealing is carried out at a temperature above 800.degree. C. The present invention will make it possible to markedly improve various characteristics of diamond films, and hence put them into practical use.

Methods for manufacturing substrates to form monocrystalline diamond

Disclosed is a diamond film field effect transistor incorporating a p-type semiconducting diamond layer of a specific thickness and B-doping concentration, which has a sufficiently large modulation of the gate voltage dependent current flowing between the source electrode and the drain electrode and whose transistor characteristics are not deteriorated even if adsorption of moisture occurs. Specifically, the diamond film field effect transistor includes; an active layer formed of a p-type semiconducting diamond wherein the concentration of a p-type impurity in the range between 10.sup.17 /cm.sup.3 and 10.sup.20 /cm.sup.3 and the film thickness is 0.14 .mu.m or less; and a gate electrode formed on the p-type semiconducting diamond active layer through an insulating layer. Further, conductive diamond layers are respectively formed between the p-type semiconducting diamond active layer and a source electrode, and between the p-type semiconducting diamond active layer and a drain electrode; and the electrically insulating diamond layer is deposited such that it also covers part of the conductive diamond layers.

Diamond film field effect transistor

A diamond film field effect transistor, excellent in characteristics and a method of manufacturing the transistor, in which a contact resistance between electrodes and respective source and drain region is small. The transistor has a channel layer of a p-layer made of semiconducting diamond, an i-layer made of high resistance diamond as a gate insulating layer, which is formed on the channel layer, a gate electrode film formed on the i-layer and a source region and a drain region formed on the surface of the i-layer in self-alignment to the gate electrode film by ion implantation using the gate electrode film, side walls and a protective film as masks.

Diamond film field effect transistor with self aligned source and drain

The highly-oriented diamond film is a diamond film formed by chemical vapor deposition, with at least 95% of its area consisting of either (100) or (111) crystal planes, and the differences {.DELTA..alpha., .DELTA..beta., .DELTA..gamma.} of the Euler angles {.alpha., .beta., .gamma.} between the adjacent crystals satisfying (.vertline..DELTA..alpha..vertline..ltoreq.1.degree., .vertline..DELTA..beta..vertline..ltoreq.1.degree. and .vertline..DELTA..gamma..vertline..ltoreq.1.degree.) simultaneously. Thus obtained highly-oriented diamond film has few grain boundaries and high carrier mobility. And the area of the diamond film can be large.

Highly-oriented diamond film

A method of forming a highly oriented diamond film having a reduced thickness with a high quality at a low cost. Surface of a single crystal substrate is cleaned, and is then left in a high vacuum of 10.sup.-6 Torr or less at a temperature between room temperature and 800.degree. C. for 15 min for releasing gas molecules absorbed on the surface of the substrate. The surface of the substrate is then processed using carbon-containing plasma for forming a barrier of obstructing a carbon component within the substrate. After that, an electric field is applied across the substrate and plasma for allowing a current to flow thereacross for a specified time, to form nuclei of diamond for synthesis of a diamond film. Thus, highly oriented diamond particles or films, in which crystal orientations thereof are epitaxial to the substrate, are synthesized.

Formation of highly oriented diamond film

A method for forming diamond films by vapor phase synthesis comprising a process of forming the diamond films on a substrate by direct current discharge plasma, in an atmosphere of a reaction gas including a gas containing at least carbon and hydrogen, or in an atmosphere of a mixed gas containing at least a carbon-containing gas and a hydrogen gas, at a gas pressure between 0.1 and 5 Torr and a substrate temperature between 300.degree. and 1000.degree. C.

Method for forming diamond films by vapor phase synthesis

A diamond Schottky diode including an electrically conductive substrate, a multi-layer structure of a semiconducting diamond layer and an insulating diamond layer, and a metal electrode. This diode has a greater potential barrier under a reversed bias and hence exhibits better rectifying characteristics with a smaller reverse current.

Diamond Schottky diode with oxygen

A is a heat-resisting ohmic electrode on diamond film, including: a p-type semiconducting diamond film; a boron-doped diamond layer provided on the semiconducting diamond film; and an electrode element made of p-type Si selectively formed on the boron-doped diamond layer; wherein the boron concentration in the boron-doped diamond layer is from 1.0.times.10.sup.19 to 1.8.times.10.sup.23 cm.sup.-3, and at least one impurity selected from the group consisting of B, Al and Ga is doped in the electrode element with a concentration from 1.0.times.10.sup.20 to 5.0.times.10.sup.22 cm.sup.-3. The ohmic electrode on diamond film is applicable for electronic devices operative at high temperature.

Diamond films with heat-resisting ohmic electrodes

Disclosed herein is a diamond Schottky gate type field effect transistor (FET) comprising: an insulating diamond under layer; a doped semiconducting diamond layer as an active layer, which has electrode areas formed by ion implantation such that the interface level is formed near the surface thereof; an insulating diamond layer formed on a portion of the semiconducting diamond layer; a source electrode made of a degenerate diamond film provided in one of the electrode areas of the semiconducting diamond layer, to form an ohmic contact between the same and the semiconducting diamond layer; a drain electrode made of a degenerate diamond film provided in the other of the electrode areas of the semiconducting diamond layer, to form an ohmic contact between the same and the semiconducting diamond layer; and a gate electrode made of a degenerate diamond film formed on the insulating diamond layer, to form a Schottky junction between the same and the semiconducting diamond layer through the diamond insulating layer.

Diamond Schottky gate type field-effect transistor

A diamond heterojunction diode having an improved rectifying characteristics with a small reverse current and a large forward current. Three layers are formed on a low-resistance p-type silicon substrate by the microwave plasma CVD in the order of a B-doped p type semiconducting diamond layer, an insulating undoped diamond layer (thinner than 1 .mu.m), and an n-type semiconducting silicon layer. Ohmic electrodes are formed on the front side of a n-type semiconducting silicon layer and the back side of a substrate. Under a forward bias, the electric field is applied to the intermediate insulating layer to accelerate the transport of holes and electrons. Under a reversed bias, the energy band has a notch as well as a potential barrier due to the intermediate layer thus preventing holes from transporting from the n-type semiconducting diamond layer to the p-type semiconducting diamond layer, resulting in the improved rectifying characteristics.

Diamond heterojunction diode

A plasma reactor for diamond synthesis includes a microwave generator, a waveguide connected to the microwave generator, an antenna disposed within the waveguide to direct the microwaves propagated along the waveguide toward the interior of a reaction chamber, a microwave window provided above the upper wall of the waveguide, a reaction chamber defined by (a) a cylindrical bottom member hermetically joined to the microwave window and the waveguide, (b) a reaction gas inlet port and a gas outlet port in the side wall thereof, and (c) a substrate holder disposed within the reaction chamber in facing opposition to the microwave window so as to be moved toward and away from the microwave window to adjust the distance between the microwave window and the substrate holder to generate a desired microwave resonance mode. A plasma is produced only in the central portion of the reaction chamber, so that the etching of the microwave window and the resulting contamination of the diamond film by impurities produced by etching the microwave window are prevented. The plasma reactor for diamond synthesis is capable of forming a high-quality diamond film on a large surface of a substrate at a high growth rate in a range of 1 to 2 .mu.m/hr.

Growing community of inventors

Kobe, Japan

Kozo Nishimura