US4309225A — Method of crystallizing amorphous material with a…

Claim 1

Independent Claim 105 words

A method of converting solid amorphous material to a more crystalline state comprising the steps of: (a) heating a portion of said material with energy from an energy beam to bring such portion to its crystallization temperature while maintaining the temperature below the melting temperature of the crystalline state of the material; and (b) moving said energy beam in relation to said material at a velocity V, which is less than or equal to V ac but fast enough to provide continuous controlled motion of the crystallization front; wherein V ac is the normalized boundary velocity of the transformation of the amorphous material to crystalline.

Claim 2

Independent Claim 105 words

A method of converting solid amorphous material to a more crystalline state comprising the steps of: (a) heating a portion of said material with energy from an energy beam to bring such portion to its crystallization temperature while maintaining the temperature below the melting temperature of the crystalline state of the material; and (b) moving said energy beam in relation to said material at a velocity V, which is less than or equal to V ac but fast enough to provide continuous controlled motion of the crystallization front; wherein V ac is the normalized boundary velocity of the transformation of the amorphous material to crystalline.

Claim 3

Dependent Claim 12 words

The method of claim 1 wherein said material comprises a semiconductor film.

Claim 4

Dependent Claim 25 words

The method of claim 2 wherein said energy beam is a laser beam, electron beam, ion beam, train of electrical pulses, or a combination thereof.

Claim 5

Dependent Claim 19 words

The method of claim 3 wherein said beam is shaped to a focused image having a large aspect ratio.

Claim 6

Dependent Claim 15 words

The method of claim 2 wherein said energy beam comprises a focused, shaped laser beam.

Claim 7

Dependent Claim 18 words

The method of claim 5 wherein said laser beam has an aspect ratio of greater than about 10.

Claim 8

Dependent Claim 25 words

The method of claim 6 wherein said semiconductor film comprises a germanium film and the laser beam employed originates from a continuous wave Nd:YAG laser.

Claim 9

Dependent Claim 14 words

The method of claim 5 wherein said laser beam is modulated spatially and temporally.

Claim 10

Dependent Claim 15 words

The method of claim 8 wherein said laser beam is focused to a slit image.

Claim 11

Dependent Claim 20 words

The method of claim 2 wherein said film is preheated with a source of heat other than said laser beam.

Claim 12

Dependent Claim 14 words

The method of claim 10 wherein said semiconductor film is supported on a substrate.

Claim 13

Dependent Claim 84 words

In the method of crystallizing an amorphous material by scanning it with an energy beam: providing continuous controlled motion of the crystallization front by (a) maintaining the background temperature of the amorphous material at a value which is between the temperature at which periodic structure occurs and the temperature which produces runaway crystallization and (b) modulating the beam and scanning a surface of the material with the beam at a rate less than or equal to the normalized boundary velocity of the crystallization front.

Claim 14

Dependent Claim 84 words

In the method of crystallizing an amorphous material by scanning it with an energy beam: providing continuous controlled motion of the crystallization front by (a) maintaining the background temperature of the amorphous material at a value which is between the temperature at which periodic structure occurs and the temperature which produces runaway crystallization and (b) modulating the beam and scanning a surface of the material with the beam at a rate less than or equal to the normalized boundary velocity of the crystallization front.

Claim 15

Dependent Claim 13 words

The improvement of claim 12 wherein said energy beam is a laser beam.

Claim 16

Independent Claim 94 words

A method for producing a crystalline semiconductor film, comprising: a. forming an amorphous film of a semiconductor on a substrate; and, b. scanning said amorphous film to crystallize it with a laser beam, said laser beam being modulated to provide continuous, controlled motion of the crystallization front, the scanning rate being less than or equal to the velocity of the crystallization front and the modulation of the laser beam being at an energy level to crystallize the material without achieving a temperature equal to or greater than the crystalline melting point of the material.

Claim 17

Independent Claim 94 words

A method for producing a crystalline semiconductor film, comprising: a. forming an amorphous film of a semiconductor on a substrate; and, b. scanning said amorphous film to crystallize it with a laser beam, said laser beam being modulated to provide continuous, controlled motion of the crystallization front, the scanning rate being less than or equal to the velocity of the crystallization front and the modulation of the laser beam being at an energy level to crystallize the material without achieving a temperature equal to or greater than the crystalline melting point of the material.

Claim 18

Dependent Claim 12 words

A method of claim 14 wherein said laser is a Nd:YAG laser.

Claim 19

Dependent Claim 14 words

A method of claim 15 wherein said amorphous film comprises an amorphous silicon film.

Claim 20

Dependent Claim 14 words

A method of claim 15 wherein said amorphous film comprises an amorphous germanium film.

Claim 21

Dependent Claim 15 words

A method of claim 15 wherein said amorphous film comprises an amorphous germanium/silicon alloy film.

Claim 22

Dependent Claim 15 words

A method of claim 15 wherein said amorphous film comprises an amorphous gallium arsenide film.

Claim 23

Independent Claim 56 words

A method of crystallizing an amorphous inorganic material in the solid phase comprising scanning said material with an energy beam sufficient to provide continuous, controlled motion of the crystallization front velocity but insufficient energy to reach the melting point of the crystalline material; the scanning rate being less than or equal to the crystallization front velocity.

Claim 24

Independent Claim 56 words

A method of crystallizing an amorphous inorganic material in the solid phase comprising scanning said material with an energy beam sufficient to provide continuous, controlled motion of the crystallization front velocity but insufficient energy to reach the melting point of the crystalline material; the scanning rate being less than or equal to the crystallization front velocity.

Claim 25

Dependent Claim 12 words

A method of claim 20 wherein said inorganic material comprises aluminum oxide.

Claim 26

Dependent Claim 12 words

A method of claim 20 wherein said inorganic material comprises silicon dioxide.

Claim 27

Independent Claim 97 words

A method of fabricating a photovoltaic cell, comprising: a. forming a conductive layer on a substrate; b. forming an amorphous semiconductor film on said conductive layer; c. scanning said amorphous semiconductor film with an energy beam at a rate which is less than or equal to the crystallization wavefront velocity and at an energy level high enough to provide continuous, controlled motion of the crystallization front to improve the crystallinity of said semiconductor film but below the melting temperature of the crystalline state of the film; and, d. forming a transparent rectifying contact with the scanned film.

Claim 28

Independent Claim 97 words

A method of fabricating a photovoltaic cell, comprising: a. forming a conductive layer on a substrate; b. forming an amorphous semiconductor film on said conductive layer; c. scanning said amorphous semiconductor film with an energy beam at a rate which is less than or equal to the crystallization wavefront velocity and at an energy level high enough to provide continuous, controlled motion of the crystallization front to improve the crystallinity of said semiconductor film but below the melting temperature of the crystalline state of the film; and, d. forming a transparent rectifying contact with the scanned film.

Claim 29

Dependent Claim 12 words

A method of claim 23 wherein said beam comprises a laser beam.

Claim 30

Independent Claim 99 words

A method of fabricated a photovoltaic cell, comprising: a. forming an amorphous semiconductor film on a transparent, conductive substrate; b. forming a rectifying contact between the amorphous semiconductor film and substrate; c. scanning said amorphous semiconductor film with an energy beam at a rate which is less than or equal to the crystallization wavefront velocity but at an energy level low enough to prevent reaching the crystalline melting point of the film to provide continuous, controlled motion of the crystallization front to improve the crystallinity of said semiconductor film; and, d. forming a conductive layer on the scanned film.

Claim 31

Independent Claim 99 words

A method of fabricated a photovoltaic cell, comprising: a. forming an amorphous semiconductor film on a transparent, conductive substrate; b. forming a rectifying contact between the amorphous semiconductor film and substrate; c. scanning said amorphous semiconductor film with an energy beam at a rate which is less than or equal to the crystallization wavefront velocity but at an energy level low enough to prevent reaching the crystalline melting point of the film to provide continuous, controlled motion of the crystallization front to improve the crystallinity of said semiconductor film; and, d. forming a conductive layer on the scanned film.

Claim 32

Dependent Claim 12 words

A method of claim 25 wherein said beam comprises a laser beam.

Claim 33

Independent Claim 100 words

A method of fabricating a photovoltaic cell, comprising: a. depositing an amorphous semiconductor layer; b. scanning said amorphous semiconductor layer with an energy beam at a rate which is less than or equal to the crystallization wavefront velocity and at an energy level low enough to avoid the crystalline melting point of the layer thereby to provide a continuous, controlled motion of a crystallization front to form a crystalline semiconductor substrate; c. forming an active semiconductor film on said substrate; d. forming a p-n junction in said active film; and, e. forming an ohmic contact to said active semiconductor film.

Claim 34

Independent Claim 100 words

A method of fabricating a photovoltaic cell, comprising: a. depositing an amorphous semiconductor layer; b. scanning said amorphous semiconductor layer with an energy beam at a rate which is less than or equal to the crystallization wavefront velocity and at an energy level low enough to avoid the crystalline melting point of the layer thereby to provide a continuous, controlled motion of a crystallization front to form a crystalline semiconductor substrate; c. forming an active semiconductor film on said substrate; d. forming a p-n junction in said active film; and, e. forming an ohmic contact to said active semiconductor film.

Claim 35

Dependent Claim 12 words

A method of claim 27 wherein said amorphous semiconductor layer comprises germanium.

Claim 36

Dependent Claim 13 words

A method of claim 28 wherein said active semiconductor layer comprises gallium arsenide.

Claim 37

Dependent Claim 13 words

A method of claim 29 wherein said p-n junction comprises a shallow homojunction.

Claim 38

Dependent Claim 19 words

A method of claim 30 including the additional step of applying an antireflection coating over said active semiconductor layer.

Claim 39

Dependent Claim 86 words

In the fabrication of a shallow homojunction solar cell from a semiconductor layer: The improvement wherein said layer is formed from an amorphous semiconductor layer scanned with an energy beam at a rate which is less than or equal to the crystallization wavefront velocity and at an energy level low enough to prevent the temperature of the layer to reach its crystalline melting point thereby to provide continuous, controlled motion of the crystallization front to form a crystalline semiconductor layer for said shallow homojunction solar cell.

Claim 40

Dependent Claim 86 words

In the fabrication of a shallow homojunction solar cell from a semiconductor layer: The improvement wherein said layer is formed from an amorphous semiconductor layer scanned with an energy beam at a rate which is less than or equal to the crystallization wavefront velocity and at an energy level low enough to prevent the temperature of the layer to reach its crystalline melting point thereby to provide continuous, controlled motion of the crystallization front to form a crystalline semiconductor layer for said shallow homojunction solar cell.

Claim 41

Dependent Claim 11 words

The improvement of claim 32 wherein said amorphous substrate comprises germanium.

Claim 42

Dependent Claim 66 words

In the method of crystallizing an amorphous material with a moving energy beam: The improvement of modulating said energy beam in conjunction with heating said material to an elevated temperature at a rate which is less than or equal to the crystallization wavefront velocity and at an energy level low enough to prevent liquifying or vaporizing the material thereby to provide a controlled, continuous crystallization front.

Claim 43

Dependent Claim 66 words

In the method of crystallizing an amorphous material with a moving energy beam: The improvement of modulating said energy beam in conjunction with heating said material to an elevated temperature at a rate which is less than or equal to the crystallization wavefront velocity and at an energy level low enough to prevent liquifying or vaporizing the material thereby to provide a controlled, continuous crystallization front.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1985-01-04	1985-07-06	1986-01-05	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1989-01-04	1989-07-06	1990-01-05	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1993-01-04	1993-07-06	1994-01-05	$7700.00	Window Closed / Lapsed

Method of crystallizing amorphous material with a moving energy beam

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