Solar cell
AssigneeGeneral Electric Company
InventorsThomas R. Anthony, Harvey E. Cline, Donald M. Winegar
Life of this patent
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Abstract
A solar cell with improved efficiency is provided with a convoluted P-N junction whereby a higher proportion of carriers produced by exposure of the solar cell to a source of radiation will be collected by the P-N junction rather than being lost by recombination. The solar cell has an increased resistance to radiation damage. The solar cell is made from a body of semiconductor material in which two regions of opposite type conductivity are formed. The material of one region is substantially the same as the body and the material of the other region is recrystallized material of the first region having solid solubility of a metal therein to impart a selective type conductivity and resistivity thereto.
Claims44
A solar cell comprising
- a body of semiconductor material having two opposed major surfaces substantially parallel to each other and a plurality of side surfaces;
- at least one of the surfaces having a preferred planar orientation which is one selected from the group consisting of <
- 100 >, <
- 110 >
- and <111 >;
- the body having a lamellar structure of integral alternate first and second regions of opposite type conductivity and a selected level of resistivity, the material of the second regions comprising recrystallized semiconductor material of the body having solid solubility of a dopant material therein to impart thereto the type of conductivity and the level of resistivity;
- a plurality of first P-N junctions, each P-N junction being formed by the contiguous surfaces of each pair of mutually adjacent first and second regions and extending between and terminating in at least two opposed surfaces of the body;
- means for electrically connecting all layers of the same type conductivity semiconductor material together into an electrical circuit arrangement, and
- means for electrically connecting the regions of like conductivity into an electrical circuit external to the solar cell.
A method for making a solar cell comprising a lamellar structure of a plurality of integral regions of alternate and opposite type conductivity and a selective resistivity, the method comprising the process steps of:
- a. selecting a body of semiconductor material having two opposed surfaces substantially parallel to each other, at least one of the surfaces having a preferred planar orientation which is one selected from the group consisting of <
- 100 >, <
- 110 >
- and <
- 111 >;
- b. etching selectively the at least one surface having a preferred planar orientation to form at least one depression in the etched surface;
- c. vapor depositing a layer of substantially oxygen free metal in the depression, the metal comprising at least one dopant material to dope the semiconductor material of the body to a specific type conductivity and a selected level of resistivity;
- d. heating the body and the vapor deposited metal to an elevated temperature to form a melt of the semiconductor material and the metal;
- e. establishing a temperature gradient substantially along a preferred crystallographic axis of the body, the selectively etched surface being at the lower temperature, and
- f. migrating the melt of semiconductor material and metal through the body substantially aligned with the preferred crystallographic axis of the body from the selectively etched surface to the opposed surface to form a region of recrystallized semiconductor material of the body having solid solubility of at least the dopant material therein to impart a selected type conductivity and a selected level of resistivity thereto and a first P-N junction at the contiguous surfaces of each pair of regions of opposite type conductivity.
Dependencies are inferred from the claim text.