COMPARISON OF TRANSPORT, RECOMBINATION, AND INTERFACIAL QUALITY IN MOLECULAR-BEAM EPITAXY AND ORGANOMETALLIC VAPOR-PHASE EPITAXY GAAS ALXGA1-XAS STRUCTURES/

We have studied free-carrier recombination and transport in GaAs struc tures prepared by different epitaxial growth techniques and with diffe rent ''surface barriers'' including molecular beam epitaxy (MBE) and o rganometallic vapor-phase epitaxy (OMVPE) prepared undoped, symmetric GaAs/Al0.3Ga0.7As double heterostructures and these same structures af ter etch removing the top Al0.3Ga0.7As layer and repassivating with Na 2S. We find 300-K lifetimes of greater-than-or-equal-to 2.5 mus (350 n s), and interface recombination velocities of 40 cm/s (250 cm/s) for o ur OMVPE (MBE) structures. Identical measurements for Na2S and bare su rfaces yield interface recombination velocities of 5500 cm/s and 34 00 0 cm/s, respectively. Free-carrier transport in both types of structur es is diffusive with hole mobilities of approximately 350 cm2/V s.