METHOD FOR SELECTIVE UNDER-ETCHING OF POROUS SILICON

摘要

A method for making a solar cell is disclosed. In accordance with the method of the present invention a composite wafer is formed. The composite layer includes a single crystal silicon wafer, a silicon-based device layer and sacrificial porous silicon sandwiched therebetween. The composite wafer is treated to an aqueous etchant maintained below ambient temperatures to selectively etch the sacrificial porous silicon and release or undercut the silicon-based layer from the single crystal silicon wafer. The released silicon device layer is attached to a substrate to make a solar cell and the released single crystal silicon wafer is reused to make additional silicon device layer.

主权项

1. A method of selectively etching a silicon wafer, the method comprising:
a) providing a sacrificial porous silicon layer on a single crystal silicon wafer; and b) selectively etching the sacrificial porous silicon layer with an aqueous etchant; wherein the aqueous etchant is maintained at a temperature in a range of 0° C. to 10° C. during step b) and the aqueous etchant comprises one or more of potassium hydroxide, sodium hydroxide and hydrogen fluoride.