Hybrid GaAsSb/GaAs Heterostructure Core-Shell Nanowire/Graphene and Photodetector Application

We report the growth of vertical, high-qualityGaAs0.9Sb0.1 nanowires (NWs) with improved density on oxygen (O2)plasma-treated monolayer graphene/SiO2/p-Si(111) by self-catalyzedmolecular beam epitaxy. An O2 plasma treatment of the graphene undermild conditions enabled modification of the surface functionalizationand improved reactivity of the graphene surface to semiconductoradatoms. The rise in the disorder peak of the Raman mode, decreasedsurface conductivity, and creation of additional O2 groups of plasmatreatedgraphene compared to that of pristine graphene confirmedfunctionalization of the graphene. To enhance the nucleation centersfurther for the vertical yield of NWs on the graphene surface, NWs weregrown on a higher Sb composition GaAs0.6Sb0.4 stem for surfaceengineering the graphene surface via the surfactant effect of Sb and forbetter lattice matching. The NWs grown under optimal conditions exhibited a zinc blende crystal structure with no discerniblestructural defects. The NWs with a GaAs-passivated shell exhibited photoluminescence emission at 1.35 eV at 4 K and 1.28 eV atroom temperature. The ensemble device fabricated with a top segment of GaAsSb NW-doped n-type using a GaTe captive sourceexhibited an optical responsivity of 110 A/W with a detectivity of 1.1 × 1014 Jones. These results of hybrid GaAsSb NWheterostructure/graphene devices show significant potential toward the fabrication of flexible near-infrared photodetector deviceapplications. Further, the simple and efficient O2 plasma treatment approach for surface engineering of graphene in conjunction witha high Sb compositional stem has shown to be a promising route that can be broadly applicable for the growth of other III−V ternarymaterial systems for improving the vertical yield of NWs.