Influence of Hydrogen Dilution on Properties of Silicon Films Prepared by D.C. Saddle-Field Glow-Discharge: Observation of Microcrystallinity

ABSTRACT In the D.C. saddle field glow discharge deposition the transition from amorphous to microcrystalline silicon thin films occurs when the silane concentration in the gas phase drops below 10%. We report here the results of Raman spectroscopy, SEM, TEM, and HRTEM studies of the film morphology. We estimate the average crystallite size to be in the range of 5 to 7 nm and the crystalline volume fraction of 25 to 35%. INTRODUCTION Amorphous Si is widely used for large area photovoltaic and microelectronic applications [1]. The use of microcrystalline Si is expected to improve stability against light-induced degradation and provide more efficient doping over that offered by amorphous silicon. Recently, we reported on the growth of mixed phase amorphous-microcrystalline silicon using the D.C. saddle field glow discharge deposition method [2]. The films were grown using hydrogen dilution of silane during the deposition. We were able to identify the growth conditions and the types of substrates that promote microcrystallinity. In this work we present the structural properties of saddle field glow discharge deposited microcrystalline Si films as a function of hydrogen dilution. The films were studied using Raman spectroscopy, SEM, TEM and high-resolution TEM.