Properties of sputtered amorphous silicon/crystalline silicon solar cells

Abstract

DC magnetron sputtering of amorphous silicon (a-Si), using an n-type silicon target, onto p-type crystalline silicon (c-Si) substrates was found to result in heterojunction solar cells. The process yielded 10.7% efficient solar cells, having a short-circuit current density (j/sub sc/) of 34 mA/cm/sup 2/ and an open circuit voltage (V/sub oc/) of 0.55 volts. The a-Si/c-Si structure had good junction characteristics, having a zero bias depletion width of 0.65 /spl mu/m in c-Si. The photovoltaic (PV) properties of the devices have been investigated for a-Si thickness, c-Si resistivity and substrate temperature. The amorphous/crystalline interface was found to be a limiting factor in device performance, and this was studied by both processing and electrical tests. The effect of interface traps due to sputtering induced damage has been studied by thermally stimulated capacitance (TSCAP) measurements.