Electrical properties of the GaAlAsSb/GaSb heterojunctions for lasers and photodetectors application

Abstract

The GaAlAsSb alloy is an interesting material for optoelectronic device technology and particularly for the preparation of lasers and photodetectors. Therefore, electrical properties of GaSb/GaAlAsSb heterojunctions are important for the characteristic devices based on them.The current-voltage characteristic of Ga0.53Al0.47As0.04Sb0.96(p)/GaSb(n+) heterojunction, obtained byliquid phase epitaxy on GaSb substrate, is studied. The current of the heterojunction, which is essentially a thermoionic emission of holes, has a behavior identical than that of the Schottky diode, which have permitted to derive the barrier height Vb = 685 meV for this heterostructure. The Richardsonconstant of the system is calculated to be 49.1 A.cm-2. K-2.The band offsets at the interface between the two semiconductors are determined as ∆EC = 460 meV, ∆EV = 128 meV, in agreement with other works. The preliminary study of the variation of the valence band offset with Al composition shows a good agreement with the theoretical models proposed by Jaros and Mujica.