Low-Frequency Noise of nc-Si:H/c-Si Heterojunction Diodes

Low-frequency noise (LFN) measurements were performed on hydrogenated nanocrystalline silicon (nc-Si:H)/crystalline-silicon heterojunction diodes for the forward- and reverse-biased currents I . The 1/ f γ noise with γ ~ 1.3 (for low I ) or 0.6 (for high I ) was observed to dominate the LFN, and the noise power spectral density Si showed a power-law behavior ( Si ~ I α , where α ~ 2). This quadratic behavior may indicate the 1/ f γ noise to stem from the carrier number fluctuations mediated by deep trap states (for γ ~ 1.3) or band tail states (for γ ~ 0.6) of nc-Si:H. Also, the band tail width of nc-Si:H was estimated to be ~ 65 meV.