Structural order of thin film silicon made at 100 °C

Abstract

Spectroscopic ellipsometric measurements showed that amorphous silicon thin films made by very high frequency plasma enhanced chemical vapour deposition at 100 °C using an optimum H2 dilution has denseness (A parameter) and structural order (C parameter) that are comparable to the sample made at 200 °C. The materials made by hot wire chemical vapour deposition (HWCVD) at low hydrogen dilution conditions have a less dense structure and higher roughness compared to the plasma deposited samples. The C parameter reaches the lowest value (C=1.67) for the HWCVD sample made at an optimum H2/SiH4 ratio of 20, even though it was made only at 100 °C. The importance of filament to substrate distance in HWCVD process in suppressing the undesirable species reaching at the growing surface has been put forward to achieve materials with very small structural disorder and fabrication of thin film silicon solar cells with high stability