Longitudinal transport in Ga1-xAlxAs p-n junctions incorporating GaAs quantum wells: Hot-electron light emitters

Abstract

Experimental results on hot-electron parallel transport in GaAs quantum wells, situated in the n-side of the depletion region of a Ga1-xAlxAs p-n junction, are presented. In our structures hot electrons are thermionically excited from the n-side of the junction into the quantum wells in the depletion region, by the application of pulsed longitudinal electric fields. The accumulation of the electrons in the depletion region modifies the potential profile of the junction, resulting in a reduction of the potential barrier and the depletion width in the p-side. Thus, hot holes are excited into the valence bands of the quantum wells via thermionic emission or tunnelling to recombine radiatively with the electrons. A simple modelling of the device is carried out by solving the Poisson and Schrodinger equations for the p-n junction incorporating a single quantum well. The results of this modelling describe the experimental observations very well. It is also shown that population inversion in the junction can be achieved at high fields. The device is therefore a very efficient light emitter with the main advantages over the conventional laser diodes being: the emitted light is independent of the polarity of the applied voltage; and only two point contacts are required, thus making it a very simple device to fabricate.