GaAsSb/InAs core-shell nanowires grown by molecular-beam epitaxy

In this paper, we report for the first time the growth of GaAsSb/InAs core-shell nanowires (NWs) on Si (111) substrates by molecular-beam epitaxy. We first grow high-quality GaAsSb NWs as cores using self-catalyzed technique, then cover these cores by InAs shells. For the growth of InAs shells, we find that the optimum beam equivalent pressure ratio of As/In is only similar to 5.2, but the growth temperature window is larger (from 460 to 540 degrees C). Also, the thickness of InAs shells increases almost linearly with extending the growth time. Because of the high-quality of GaAsSb cores, the InAs shells are continuous, smooth, and without stacking faults or twins adopted from the cores. Temperature dependent I-V curves measured from the field-effect transistor devices based on these GaAsSb/InAs core-shell NWs indicate that GaAsSb/InAs NWs without any intentional doping are electrically conductive. The growth of GaAsSb/InAs coreshell NWs opens up new possibilities for both fundamental studies and future device applications based on such natural p-n junctions. (C) 2017 Elsevier B.V. All rights reserved.