TRANSPORT-PROPERTIES OF INTRINSIC HYDROGENATED AMORPHOUS-SILICON PRODUCED BY THE HOT-WIRE TECHNIQUE INVESTIGATED BY THE PHOTOMIXING TECHNIQUE

The transport properties of hydrogenated amorphous silicon (a-Si:H) wi th a hydrogen content ranging from 12% to less than 1%, which were pro duced by the hot-wire technique, varying the deposition substrate temp erature. 290 degrees C<T-S<400 degrees C, were systematically studied by the photoconductive frequency mixing technique. With an increase of the deposition substrate temperature, and consequent decrease of hydr ogen content, the photoconductivity, sigma(pc), and the drift mobility , mu(d), are found to decrease, while the width of the conduction band tail, epsilon, increases. Continuous degradations of photoconductivit y, drift mobility. and photomixing lifetime. tau, were found during li ght soaking experiments. In addition. it was found that the drift mobi lity increases and the photomixing lifetime decreases with an increase of the applied electric field, while the photoconductivity is essenti ally independent of the electric field within the range of 1000-10 000 V cm(-1). Furthermore, the electric field dependence of the drift mob ility in the annealed state is always larger than in the light-soaked state, The results for the electric field dependence are explained usi ng the model of long-range potential fluctuations, whose range can be determined by employing an analysis previously developed. (C) 1997 Ame rican Institute of Physics.