Method for improving the crystallinity of semiconductor films by laser beam scanning and the products thereof
AssigneeMassachusetts Institute of Technology
InventorsJohn C. C. Fan, Herbert J. Zeiger
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Abstract
A method is disclosed for improving the crystallinity of semiconductor films by scanning the surface of such films with a shaped, focused laser beam. The laser is matched to the film so that the beam delivers sufficient energy thereto to heat the film above a temperature at which crystallization occurs along the scan track.
Claims34
A method for improving the crystallinity of a semiconductor film by scanning it with a focused beam from a continuous wave laser having a wavelength at which the semiconductor film has an absorption coefficient sufficient to allow laser radiation to be absorbed over the semiconductor film thickness.
A method for producing a crystalline silicon film from an amorphous silicon film by scanning said amorphous film with a focused laser beam produced by a continuous wave Nd:YAG laser at a rate sufficient to produce crystallization within said amorphous film.
A method for fabricating a photovoltaic cell, comprising:
- a. forming a conductive layer on a substrate;
- b. depositing a semiconductor film on said conductive layer;
- c. scanning the semiconductor film with a focused beam from a laser to improve the crystallinity of said semiconductor film;
- and,
- d. forming a transparent rectifying contact with the scanned film.
A method for fabricating a photovoltaic cell, comprising:
- a. depositing a semiconductor film on a transparent, conductive substrate;
- b. forming a rectifying contact between the semiconductor film and substrate;
- c. scanning the semiconductor film with a focused beam from a laser to improve the crystallinity of said semiconductor film;
- and,
- d. forming a conductive layer on the scanned film.
A method for producing a crystalline semiconductor film, comprising:
- a. depositing an amorphous film of a semiconductor on a substrate;
- and,
- b. scanning said amorphous film to crystallize it with a laser beam having a wavelength which is significantly absorbed across the thickness of said amorphous film and significantly transmitted by the crystallized semiconductor film.
Dependencies are inferred from the claim text.