Theory of photoconductivity in amorphous semiconductors containing relatively narrow trap bands

Abstract

For a constant rate G of generation of electron-hole pairs, lg J_ph (J_ph is the photocurrent) increases as T^-1 at high temperatures and reaches a maximum value of J_m at T=T_m. Thereafter, lg J_ph decreases as T^-1 with further decrease in temperature and finally, at low temperatures, J_ph becomes independent of temperature. The lg J_ph against T^-1 characteristics scale to high current and T_m increases with increasing G. At constant temperature, say T₁, J_ph is a linear function of G up to the value of J_m corresponding to T₁, and in this range the curves scale to higher currents levels with decreasing T. For J_ph>J_m, J_ph increases as G¹2/, and in this range the curves scale to high current levels with increasing T. At very high light levels or at low temperatures, corresponding to the case where J_ph is temperature independent, the J_ph against G curves for different constant temperatures all merge and J_ph is found to be linearly proportional to G.