Reduction of Deep Level Impurities in Zn-Doped AlxGa1-xAs by a Co-Dopant Technique

Abstract
By using a novel co-dopant technique in the metalorganic chemical vapor deposition (MOCVD) process, we have achieved very low deep level densities (Nt13cm-3) and improved optical properties in Zn-doped (NA-ND=1×1018cm-3) Al0.2Ga0.8As epitaxial layers. This technique employed both p- (Zn) and n-type (Se) dopants in the growth of p-type Al0.2Ga0.8As. Samples were characterized by deep level transient spectroscopy (DLTS) and photoluminescence (PL). We have found that a small amount of Se (n∼8×1016/ cm3) in Zn-doped (p∼1×1018/ cm3) Al0.2Ga0.8As will significantly reduce the density of deep level impurities (by more than one order of magnitude) and increase the photoluminescence efficiency.