Wedged Channel Vertical Junction Silicon Solar Cell.
DEPARTMENT OF THE AIR FORCE WASHINGTON DC
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The present invention provides a novel vertical junction solar cell structure comprising a silicon chip having in one surface a plurality of short, wedge-shaped channels closely spaced in an array and separated by thin vertical ribs which are configured to substantially eliminate any rib fracture problems. The junction is diffused over the rib surfaces and chip surfaces between the ribs. The cell is fabricated from a chip having the surface parallel to the 110 crystallographic planes, and the channels are aligned along the 111 planes following conventional technique. Unconventional control of the length 1 of the channel forming the vertical junctions, however, allows substantial control of channel depth d, approximately according to the relationship d 12 square root of 3. Vertical junction cells according to the present invention are thus characterized by deeper channel construction which results in substantially increased light utilization at end-of-life condition, and improved fabrication process control, as well as improved radiation resistance, conversion efficiency and mechanical integrity. It is therefore an object of this invention to provide an improved efficiency silicon solar cell. It is a further object of this invention to provide a vertical junction solar cell having improved mechanical strength and light-absorbing characteristics.
- Electric Power Production and Distribution