AC electrical properties of Schottky diode based on nanocrystalline silicon thin films

Thin film of hydrogenated amorphous silicon has been deposited with plasma enhanced chemical vapor deposition technique. The obtained samples were thermally annealed at 700 degrees C and 900 degrees C to get nanocrystalline silicon. The energy band gap has been determined using the Tauc's model for indirect transitions. The band gap of the layer increases from 1.75eV to 2.1 eV as the annealing temperature increases and indicates a structure change from amorphous to nanocrystalline phase. The electrical characterization of the Au/nc-Si:H Schottky diodes was performed using conductance-voltage-frequency (G/omega-V) and capacitance-voltage (C-V) measurements. The presence of a peak in C-V characteristic and the increase of capacitance with decreasing frequency is a signature of a continuous distribution of interface states. According to characteristic analysis, the amorphous region and nanocrystalline phase dominated over distinguishable frequency scales. The response of the former one emerges at low frequencies whereas the other stands out at extremely high frequencies.