Indium tin oxide sputtering damage to catalytic chemical vapor deposited amorphous silicon passivation films and its recovery

Abstract

We investigated the influence of indium tin oxide (ITO) sputtering damage to various types of amorphous silicon (a-Si) passivation films deposited by catalytic chemical vapor deposition. Intrinsic (i-) a-Si, n-type (n-) a-Si/i-a-Si, and p-type (p-) a-Si/i-a-Si stacked films were prepared on crystalline Si, and ITO was sputtered at various temperatures and RF powers, followed by post-annealing at 200°C. Effective minority carrier lifetime (τeff) of almost all the samples decreases drastically after sputtering, while τeff of the samples with ITO sputtered at room temperature recovers significantly by post-annealing. Annealing before sputtering and sputtering at lower RF power leads to more effective recovery of τeff. The samples with ITO sputtered to an n-a-Si/i-a-Si stack show large τeff recovery, while the samples with ITO sputtered to a p-a-Si/i-a-Si stack show much smaller τeff recovery. τeff recovery after ITO sputtering thus depends on the types of a-Si passivation films, which may be related to the modification of band alignment by the existence of ITO.