Explanations of inconsistencies in capacitance–voltage profiles of normal and inverted heterostructures

The carrier distributions, obtained from capacitance–voltage measurements on semiconductor heterojunctions, are widely different, depending on whether the Schottky barrier is on the higher band gap semiconductor or on the lower band gap semiconductor. The actual carrier distributions as calculated in both cases are quite dissimilar from the measured distributions. Explanations for such observations have been sought through rigorous studies based on self-consistent solutions of Schrödinger and Poisson equations applied to the widely used GaAs/AlGaAs heterojunctions. It emerges that the nature of the carrier distributions is mostly dependent on the effects of the Debye smearing on the two dimensional and three dimensional components of the capacitances at the heterostructures. The applied electric field, necessary for measurements does not have a significant effect on the carrier distribution.