Spin-dependent conductivity in amorphous hydrogenated silicon

Additional results concerning spin-dependent transport (photoconductivity and dark conductivity) in undoped, doped, and compensated amorphous hydrogenated silicon are reported. Undoped samples show, in addition to the known dangling-bond and tail-state resonances, a broad line which is attributed to excitonic states and is demonstrated to be involved in light-induced degradation. In n-type and compensated samples, trapping and hopping in donor states is directly identified in spin-dependent conductivity. Implications of these results for recombination models are discussed.