Process for preparing diamond thin film

Claim 2

A process for preparing a diamond thin film which is characterized in that a top surface of a plate substrate is maintained at a temperature of at least more than 400 degrees c in an atmosphere of a mixed gas of a hydrogen and a hydrocarbon in a reduced pressure, while said top surface is subjected to electron bombardments and charged-up electrons are removed, thereby diamond crystal nucleuses are caused to form and growth to a thin film on said top surface of the plate substrate.

Claim 3

A process according to claim 1, wherein the temperature of said top surface of the plate substrate is maintained at 400 to 900 degrees C.

Claim 4

A process according to claim 1, wherein the volume ratio of the hydrocarbon and the hydrogen is 1/1 to 1/200 and said atmosphere of said mixed gas is maintained at a pressure of 10 -5 to 50 Torr.

Claim 5

A process according to claim 1, wherein the electron current density bombarded on said top surface of the plate substrate is 1 to 200 mA/cm 2 .

Claim 6

A process according to claim 1 or 3, wherein the hydrocarbon consists of one or more lower hydrocarbons which are saturated or unsaturated and chain or cyclic compounds.

Claim 7

A process according to claim 5, wherein the hydrocarbon is methane, acetylene or benzene.

Claim 8

A process according to claim 1, wherein said substrate consists of a haet-resisting inorganic material having a melting point of at least more than 600 degrees C.

Claim 9

A process according to claim 7, wherein said heat-resisting inorganic material consists of an elemental metal, an alloy, a ceramics, a glass, a carbon or these composite materials.

Claim 10

A process according to any one of the preceding claims, wherein a holder of a plate substrate is fixed in a heating cylinder arranged in an evacuated container, said plate substrate is mounted on said holder, a heating material for an electron emission is positioned in a predetermined space opposite to said plate substrate, electron bombardments are subjected to said top surface of the plate substrate, said electrons being emitted from the heating material loaded an electric current and by an impressed voltage of a negative charge to said heating material and a positive charge to said holder through a direct current source, while a charged-up electron on said top surface is removed through an earthed circuit of the positive and negative terminals of said direct current source and the earth, a mixed gas of a predetermined volume ratio of a hydrogen and a hydrocarbon is introduced through a pipe opened in said heating cylinder by penetrating the wall of said container with a maintenance of the inner pressure of said container at a predetermined pressure, said top surface of the plate substrate is heated by said heating cylinder with a maintenance of a predetermined temperature and thereby diamond crystal nucleuses are caused to form and growth to a thin film on said top surface of said plate substrate.

Claim 11

A process according to claim 9, wherein the earthed circuit is connected with another earthed circuit removing the charged-up electrons through the negative terminal of the direct current source, a capacitor and a high-frequency generator and the earth.

Claim 12

A process according to any one of claims 1 to 8, wherein a holder of a plate substrate is arranged in an evacuated container, said plat substrate is mounted on said holder, an indirect heating means is arranged to heat the top surface of the plate subsrate from.the side of said top.surface and maintain a predetermined temperature of said top surface, a mixed gas of a predetermined volume ratio of a hydrogen and a hydrocarbon is introduced in said container through a pipe with a maintenance of the inner pressure of said container at 10 -5 to 10 -2 Torr, an electron gun is arranged in said container to bombard the top surface of the plate substrate with electrons, said holder is connected with a charged-up electron removing means and thereby diamond crystal nucleuses are caused to form and growth to a thin film on said top surface of the plate substrate.

Claim 13

A process according to claim 11, wherein said electron gun is arranged over the top surface of the plate substrate to bombard said top surface with electron beams.

Claim 14

A process according to claim 12, wherein said electron beams are scanned on said top surface.

Claim 15

A process according to claim 11, wherein said electron gun is arranged on the side of said plate substrate and the electron beam orbit is diffusionally deflected with a deflection magnet to bombard a predetermined range of the top surface with electrons.

Claim 16

A process according to claim 11, wheren said charged-up electron removing means consists of an earthed cirucit through the holder, a capacitor, a high-frequency generator and the earth, or a earthed circuit through the holder, positive and negative teminals of a direct current source and the earth, or the combination of both said earthed circuits.

Claim 17

A process for preparing a p-type diamond semiconductor which is characterized in that a top surface of a plate substrate is maintained at a temperature of at least more than 400 degrees C in an atmosphere of a mixed gas of hydrogen and a hydrocarbon and a diborane, while said top surface is subjected to electron bombardments and charged-up electrons are removed, therby diamond crystal nucleuses are caused to form and growth to a thin film of the p-type diamond semiconductor on said top surface of the plate substrate.

Claim 18

A process for preparing a p-type diamond semiconductor which is characterized in that a top surface of a plate substrate is maintained at a temperature of at least more than 400 degrees C in an atmosphere of a mixed gas of hydrogen and a hydrocarbon and a diborane, while said top surface is subjected to electron bombardments and charged-up electrons are removed, therby diamond crystal nucleuses are caused to form and growth to a thin film of the p-type diamond semiconductor on said top surface of the plate substrate.

Claim 19

A process according to claim 16, wherein the volume ratio of the hydrocarbon and the hydrogen is 1/1 to 1/200 and the diborane is added in 1 p.p.m. to 1 p.p.b to the volume of the hydrocarbon.

Claim 20

A process according to claim 16 or 17, wherein the mixed gas is introduced to 10 -5 to 50 Torr in the container.

Claim 21

A process according to claim 16, 17 or 18, wherein the top surface of the plate substrate is maintained at 400 to 900 degrees C.

Claim 22

A process according to any one of claims 16 to 19, wherein an electron current density on the top surface is 1 to 200 mA/cm 2 .

Claim 23

A process according to: claim 16, wherein charged-up electrons are removed through an earthed circuit of the holder, positive and negative terminals of a direct current source and the earth, or an earthed circuit of the holder, a capacitor, a high-frequency generator and the earth, or the combinations of both said earthed circuits.

Claim 24

An abrasive material for a high cooling consits of the diamond thin film adhered to the surface of the plate substrate according to the process of claim 1.

Claim 25

An electrical insulating material for a high cooling consists of the diamond thin film adhered to the surface of the plate substrate according to claim 1.

Claim 26

A hardwearing material for a high cooling consists of the diamond thin film adhered to the surface of the plate substrate according to claim 1.