Effect of deposition temperature on the growth of nanocrystalline silicon network from helium diluted silane plasma

The effect of deposition temperature on nanocrystallization and, thereby, on different optical, electrical and structural properties of the Si : H network has been studied by radio frequency (RF)-plasma enhanced chemical vapour deposition, at a moderate RF-power (100 W) and moderate pressure (0.5 Torr), using silane as the source gas and helium as the only diluent, without hydrogen. Structural characterizations of the films have been performed by infrared absorption, x-ray diffraction and high-resolution transmission electron microscopy studies. Optical characterization has been performed by UV-VIS absorption and photoluminescence (PL) studies. Nanocrystallization has been initiated in the network at deposition temperatures above 150 degrees C, aided by helium in the plasma with its atomic, ionic and metastable species. The nc-Si : H films with well-identified lattice planes of mostly < 111 > orientation have been obtained with a reasonably high deposition rate (similar to 90 angstrom min(-1)). The nc-Si : H films demonstrate good electrical conductivity (sigma(D) similar to 10(-3) S cm(-1)) and exhibit room temperature PL.