Directional solid phase crystallization of thin amorphous silicon for solar cell applications
First Claim
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1. A method of heat treating a crystalline silicon substrate, comprising:
- depositing an amorphous silicon film on a first surface of the crystalline silicon substrate, wherein the first surface of the crystalline silicon substrate is opposite to a second surface of the crystalline silicon substrate, a first surface of the amorphous silicon film is opposite to a second surface of the amorphous silicon film, and an interface is formed between the first surface of the crystalline silicon substrate and the second surface of the amorphous silicon film; and
heating the crystalline silicon substrate and the amorphous silicon film to a temperature that is sufficient to crystallize the amorphous silicon film by solid phase crystallization, wherein the heating creates a temperature gradient in which the temperature at the second surface of the crystalline silicon substrate is greater than the temperature at the first surface of the amorphous silicon film, and the temperature gradient is between about 2°
C. and about 10°
C.
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Abstract
Embodiments of the present invention provide a method for converting a doped amorphous silicon layer deposited onto a crystalline silicon substrate into crystalline silicon having the same grain structure and crystal orientation as the underlying crystalline silicon substrate upon which the amorphous silicon was initially deposited. Additional embodiments of the present invention provide depositing a dielectric passivation layer onto the amorphous silicon layer prior to the conversion. A temperature gradient is provided at a temperature and for a time period sufficient to provide a desired p-n junction depth and dopant profile.
44 Citations
20 Claims
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1. A method of heat treating a crystalline silicon substrate, comprising:
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depositing an amorphous silicon film on a first surface of the crystalline silicon substrate, wherein the first surface of the crystalline silicon substrate is opposite to a second surface of the crystalline silicon substrate, a first surface of the amorphous silicon film is opposite to a second surface of the amorphous silicon film, and an interface is formed between the first surface of the crystalline silicon substrate and the second surface of the amorphous silicon film; and heating the crystalline silicon substrate and the amorphous silicon film to a temperature that is sufficient to crystallize the amorphous silicon film by solid phase crystallization, wherein the heating creates a temperature gradient in which the temperature at the second surface of the crystalline silicon substrate is greater than the temperature at the first surface of the amorphous silicon film, and the temperature gradient is between about 2°
C. and about 10°
C. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method of heat treating a crystalline silicon substrate to form a p-n junction, comprising:
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depositing an amorphous silicon film on a first surface of the crystalline silicon substrate, wherein the first surface of the crystalline silicon substrate is opposite to a second surface of the crystalline silicon substrate, a first surface of the amorphous silicon film is opposite to a second surface of the amorphous silicon film, and an interface is formed between the first surface of the crystalline silicon substrate and the second surface of the amorphous silicon film; depositing a dielectric layer over the amorphous silicon film; and heating the crystalline silicon substrate and the amorphous silicon film to a temperature that is sufficient to crystallize the amorphous silicon film by solid phase crystallization, wherein the heating creates a temperature gradient between the second surface of the crystalline silicon substrate and the first surface of the amorphous silicon film in which the temperature at the first surface of the crystalline silicon substrate is greater than the temperature at the first surface of the amorphous silicon film, and the temperature gradient is between about 2°
C. and about 10°
C. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18)
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19. A method of heat treating a crystalline silicon substrate, comprising:
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depositing an amorphous silicon film on an upper surface of the crystalline silicon substrate during a plasma enhanced chemical vapor deposition process within a deposition chamber, wherein the upper surface of the crystalline silicon substrate is opposite to a lower surface of the crystalline silicon substrate, an upper surface of the amorphous silicon film is opposite to a lower surface of the amorphous silicon film, and an interface is formed between the upper surface of the crystalline silicon substrate and the lower surface of the amorphous silicon film; and heating the crystalline silicon substrate and the amorphous silicon film to a temperature that is sufficient to crystallize the amorphous silicon film by solid phase crystallization within the deposition chamber, wherein the heating creates a temperature gradient in which the temperature at the lower surface of the crystalline silicon substrate is greater than the temperature at the upper surface of the amorphous silicon film. - View Dependent Claims (20)
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Specification