Conductance fluctuations in undoped intrinsic hydrogenated amorphous silicon films prepared using several deposition techniques

Coplanar conductance fluctuations in a range of device quality undoped hydr ogenated amorphous silicon (a-Si:H) films prepared using different depositi on systems were measured in the temperature range of 440-505 It for frequen cies from 2 Hz to 3 kHz. The 1/f(x) type noise spectra had two different po wer law dependencies, one at lower frequencies with slope alpha(1) dose to unity and a second region at higher frequencies with slope alpha(2) around 0.60. The noise power density decreases with increasing temperature in the high frequency region, but only increases much less with temperature at low frequencies. The results indicate that the noise in undoyed intrinsic a-Si :H films is due to two independent noise mechanisms operating simultaneousl y. (C) 2000 Elsevier Science B.V. All rights reserved.