Determining local state densities in spatially inhomogeneous samples from steady-state space-charge-limited currents

The effect of spatial inhomogeneity of the distribution of local levels on the reliability of the determination of the densities of these states from steady-state space-charge-limited current-voltage characteristics is discussed. Numerical calculations of correction factors show that experimentally determined apparent densities of local states are close to spatially averaged values. In some cases, information about their spatial distribution can be deduced from measurements of the thickness dependence of the apparent density of states.