High rate deposition of microcrystalline silicon solar cells using 13.56 MHz PECVD

Abstract

In this paper, the authors present microcrystalline silicon (/spl mu/c-Si:H) p-i-n solar cells prepared at high deposition rates using plasma-enhanced chemical vapour deposition (PECVD) at 13.56 MHz excitation frequency. They studied the deposition regime of high RF-power P/sub RF/ (40-100 W for a 150 cm/sup 2/ electrode) and high deposition pressure p/sub dep/ (1-11 Torr) at different silane concentrations and substrate temperatures. In this regime, the prepared i-layers were amorphous or microcrystalline depending on the deposition parameters. The shift between the two growth regimes was achieved by a variation of either deposition pressure, plasma power or silane concentration. The best /spl mu/c-Si:H solar cells were prepared close to the transition to amorphous growth. A high deposition pressure was a prerequisite for obtaining high quality material at a high growth rate. The best solar cell efficiency achieved was 8.0% at 5 /spl Aring//s for a /spl mu/c-Si:H single junction solar cell.