Journal of Vacuum Science & Technology A, Vol.18, No.2, 661-664, 2000
1/f noise in p-type amorphous silicon
We have measured conductance fluctuations in four samples of p-type hydrogenated amorphous silicon, two doped at 10(-4) and the other two at 5 x 10(-2), at temperatures between 22 and 200 degrees C, The noise power density varies for the most part as 1/f(alpha) in the frequency range 2 Hz to 1 Wt, although deviations from a strict power law are observed. In all samples, the magnitude of the noise trends higher with temperature typically increasing by a factor of 5 over the temperature range. alpha also increases with temperature from near unity to over 1.4. The magnitude of the noise decreases as the Fermi level moves toward the valence band with increased doping. The dependence on doping and temperature is inconsistent with generation-recombination noise. Above 180 degrees C for the 10(-4) doped samples, the noise fails to scale as the square of the bias current at low frequencies.