Carrier emission from defects in intrinsic hydrogenated amorphous silicon studied by junction-capacitance methods

• We measure the capacitance transient in undoped amorphous silicon.
• We examine this transient measured at a wide range of temperature.
• We find that the transient curves which fit only with function represent a power low and squeeze exponential.
• These results were attributed to carrier transitions at localized states near the edge band.
• These localized states were attributed to filament structures formed at void surface.

Capacitance transient measurements have been performed on undoped hydrogenated amorphous silicon samples. The transient decays measured at wide range of temperatures and pulse durations cannot be fitted by power-law (as in the case of n-type) or by a sum of power-law and stretched-exponentials (as in the case of p-type) but with the sum of stretched and squeezed exponentials. The observed decays were attributed to carrier transition from localized states situated near the extreme edges of both band tails. These localized states are due to filamentary structure formed at void surfaces.