New Technique for Suppressing Oxygen Impurity in AlGaAs Layer during Molecular Beam Epitaxy by Surface Segregation

Abstract

A new technique for decreasing oxygen concentration in the AlGaAs layer during molecular beam epitaxy (MBE) is proposed on the basis of oxygen incorporation. In this technique, the growth temperature is successively decreased at each interface where the AlAs mole fraction is changed. The secondary ion mass spectroscopy (SIMS) analysis indicates that both oxygen concentration near the active layer and the oxygen peaks at each interface, which are commonly observed using the layer grown by a conventional method, are effectively suppressed by the new technique. The laser diode fabricated from the wafer shows characteristics superior to those of the lasers fabricated by a conventional method. For example, the threshold current density is as low as 1.1 kA/cm2.