Light induced degradation and structure of high efficiency a-Si:H, a-SiGe:H and a-SiC:H solar cells

Abstract

The electrical and optical properties of a‐Si:H, a‐SiGe:H and a‐SiC:H films prepared by d.c. glow discharge method have been characterized. High performance p‐i‐n devices have also been prepared. The relative stability as well as initial properties of these materials was examined as a function of growth rate. Notable solar cells include efficiencies of 9.36% for a‐Si:H deposited at 10Å/sec, 8.6% for a‐SiGe:H and 7% for a‐SiC:H. Cells employing I‐layers of a‐Si:H grown at rates greater than 10Å/sec were significantly less stable than standard material. Cells using I‐layers of either a‐SiGe:H or a‐SiC:H were stable (compared to standard a‐Si:H) when they were prepared at growth rates of less than 1.0Å/sec. An increase in the infrared absorption at 845 cm−1 was associated with an increase in the rate of light induced degradation. Absorption at 845 cm−1, is usually associated with the bending modes of (SiH2)n polymeric chains.