Effect of the depletion layer capacitance on the mobility determination using transient current extraction of doping-induced charge carriers

Abstract

We use drift-diffusion simulations to clarify the effect of a steady-state depletion layer on the mobility determination using the charge extraction by linearly increasing voltage (CELIV) technique in case of extraction of doping-induced charge carriers. Accounting for the steady-state depletion layer gives rise to a saturation of the extraction current transients to a capacitive regime limited by the depletion layer capacitance. As a consequence of this saturation effect, the standard mobility formulas can overestimate the mobility by several orders of magnitudes if the voltage ramp-up rate is not sufficiently large. Based on the simulations, we present an expression to extract the mobility from CELIV, which takes the displacement current of the depletion layer into account.