Optoelectronic properties of hydrogenated amorphous silicon films grown using a modified pulsed plasma discharge

Hydrogenated amorphous silicon (a-Si:H) films were deposited by a modified pulsed plasma decomposition of silane and disilane in which a nonzero low power level was maintained throughout the discharge. Deposition rate (r(d)), optical band gap (E(g)), dark and photoconductivity (sigma(D) and sigma(ph)), and photosensitivity (sigma(ph)/sigma(D)) were investigated as a function of pulse parameters. By combining dwell time (tau) and the high power level (HPL) it has been shown that E(g) can be tailored over a fairly wide range. Similarly, sigma(D) and sigma(ph)/sigma(D) have been shown to depend, in addition to HPL, on tau as well, thereby proving the possibility of using tau as an additional process parameter. High band-gap a-Si:H material of quality (sigma(ph) = 4.4 X 10(-6) Omega(-1) cm(-1), sigma(ph)/sigma(D) approximate to 10(5)) comparable to that of device quality a-Si:C:H has been deposited by this technique. (C) 1996 American Institute of Physics.