Current transport in relaxation-case GaAs

Abstract

Current-voltage characteristics of $p-\nu -n$ structures, where the $\nu$ region is oxygen-doped relaxation-case GaAs, have been redetermined with particular attention given to the characterization of the contacts to the high-resistivity $\nu$ layer. The forward characteristics exhibit near-Ohmic behavior up to applied voltages that are considerably larger than the built-in potential, which is then followed by a range of sublinear increase of current with voltage. These results are consistent with earlier observations and provide evidence that the characteristics are determined by a space-charge region of increased resistance adjoining the injecting $p$ contact. The results are discussed in relation to the relaxation-case theory which ascribes the sublinear current increase to the growth of this space-charge region by recombinative injection, i.e., depletion of the majority carriers through recombination with the injected minority carriers before dielectric relaxation can occur. Questions regarding this interpretation and its implications regarding relaxation-case recombination and trapping are discussed.