Potential barriers and current-voltage characteristics of <i>p</i>-doped graded AlAs-GaAs heterojunctions

Abstract

Detailed calculations are presented of the potential shape of graded AlAs-GaAs heterojunctions and of the current-voltage characteristics across the heterobarriers using a variational wave-function model. Tunneling currents are taken into account and it is shown that common models based on thermionic emission are not applicable for low temperatures, high applied voltages, and heavily doped semiconductors. The resistivity of the junction is shown to be strongly temperature dependent. The recently reported low resistivities of graded-gap mirrors in vertical cavity laser diodes can be explained with a simple variational wave-function model.