Spectroscopic study of polysilicon traps by means of fast capacitance transients

The energy distribution of polysilicon traps is studied by means of a simple methodology based on the measurement of fast capacitance transients observed after disturbing metal/oxide/poly-Si/Si structures with positive and negative gate voltage pulses. This methodology relies on the well-known deep-level-transient spectroscopy technique. Amorphous silicon presents two defect bands at 0.31 and 0.58 eV below the conduction band whose magnitudes are significantly reduced after spike anneal. An increasing defect tail is observed toward the valance band whose magnitude can be drastically suppressed by a proper postdeposition anneal.