Surface photovoltage spectroscopy in hydrogenated amorphous silicon

Properties of the amorphous silicon Schottky barrier are investigated by surface photovoltage spectroscopy. A model of the recombination of carriers at the rectifying metal/amorphous silicon interface is presented, and tested by using it to calculate the surface photovoltage induced on a Schottky barrier by modulated light. A method is developed for the determination of the surface recombination velocity, surface recombination rate, built-in voltage of the barrier, and the junction ideality factor, using low frequencies of modulated light. Analysis of the data at intermediate frequencies yields the minority-carrier diffusion length. The junction capacitance and density of states near the Fermi level are deduced from high-frequency measurements.