ANALYSIS OF TCO P(A-SI-C-H) HETEROJUNCTION AND ITS INFLUENCE ON P-I-NA-SI-H SOLAR-CELL PERFORMANCE

The ASPIN computer simulator, which enables analysis of transparent co nducting oxide (TCO)/a-Si:C:H/a-Si:H/TCO heterostructures, was used to examine the influence of different front TCO/p(a-Si:C:H) heterojuncti ons on TCO/p-i-n/TCO/metal a-Si:H solar cell performance. Separate ana lysis of TCO/p(a-Si:C:H) structure for both SnO2 and ZnO indicates tha t the mismatch between the high contact potential and the measured pot ential barrier at the p-layer surface can be resolved by a large densi ty of interface defect states, causing a steep potential decrease in t he interface. Analysis of the detrimental effects of a-Si:C:H chemical oxidation in SnO2/p(a-Si:C:H), which were simulated by the increased surface state density in the a-Si:C:H, showed that the potential barri er in a p-layer with oxidized surface is increased. The impact of both TCO/p(a-Si:C:H) interface states and a-Si:C:H surface states on the p hotoelectric properties of p-i-n a-Si:H solar cells is discussed, and a possible improvement of V infinity is envisaged.