THEORETICAL-STUDY ON OPTIMUM BARRIER HEIGHT OF GAAS/ALXGA1-XAS MULTIPLE-QUANTUM-WELL MODULATOR - INHOMOGENEOUS BROADENING EFFECTS

Abstract

The optimum barrier height of GaAs/AlxGa1-xAs multiple quantum well for the static property of the optical modulator is studied including exciton line broadening effects. The exciton binding energy, oscillator strength, and radius are calculated with respect to Al composition x in the barrier. Inhomogeneous line broadening of exciton lines due to interface roughness and alloy disorder are also calculated. Interface roughness broadening increases substantially as x increases while oscillator strength is not changed so much. It is shown that the optimum barrier height is strongly dependent on the dominant broadening mechanism. The optimum barrier height occurs at the lower barrier as the inhomogeneous broadening becomes more dominant.