New method of definition of mobility of nonequilibrium carriers in semiconductors

A radically new method is suggested for drift mobility determination in semiconductors; this method is based on the measurement of how much time it takes to attain a peak value of the diffusion-drift current of nonequilibrium charge carriers excited by short pulses of light from a high-absorption region through one of the contacts. The estimations show that the method is applicable if the drift flow exceeds the diffusion flow. This condition is satisfied at voltages exceeding those corresponding to the highest rate of tmax(U) decay. Mobility μ can be calculated by the formula μ=d2(2Utmax)-1, where d is the distance between contacts, U is the applied voltage, and tmax is the time the peak value of the photocurrent is attained.