Abstract
Graphene is promising as a transparent, flexible, and possibly cost-effective substrate for nanowire-based devices. We have investigated Au-seeded III–V nanowire growth with graphite as a model substrate. The highest yield of undoped vertical nanowires was found for InAs, but we also observed vertical nanowires for the InP, GaP, and GaAs materials. The yield of vertical nanowires for GaP and GaAs was strongly improved by supplying the p-dopant DEZn before nanowire growth but not by supplying H2S or HCl. In-plane GaAs and GaP nanowire growth exhibited an unexpected behavior, where the seed particles seemingly reflected on the side facets of other nanowires. These results pave the way for vertical and in-plane hybrid graphene- nanowire devices.
Highlights
The rising interest in graphene has mainly been driven by its unique electronic properties.[1]
III−V NWs have shown promising performance in solar cells,[4−8] electronics,[9−12] and light emitting diodes,[13,14] but the commercial development is partially hampered by the high cost of III−V substrates
Reports on Au-seeded growth of III−V NWs on graphene are scarce,[24,27] but in this Letter we demonstrate that it is possible to grow vertical and in-plane Au-seeded NWs of all four regular III−V materials on graphite
Summary
That it is possible to grow vertical NWs of all four materials. For GaP and GaAs, we report a strong improvement in the yield of vertically grown NWs by adding Zn before growth. GaSb has been predicted to have a relatively good lattice matching with graphene.[23] in this case γGS > γSV = 1.1 J/m2, and we assume similar values for other III−Vs. The high interfacial energy reflects the weak interaction between graphite and III−Vs, which is manifested in the lack of substrate growth in our experiments. We observe that Zn strongly improves the vertical NW nucleation for GaP and GaAs. From the annealing experiments, we find that Zn reduces the contact angle of Au−Ga particles on graphite, which according to eq 2 suggests that γLG is reduced. Munshi et al discussed the lattice matching between the III−V NW and the graphite substrate,[23] and one possibility is that a good lattice matching expresses itself as a low γGS This could be the case for undoped InAs NWs, which shows by far the highest yield of undoped vertical NWs here. These results pave the way for hybrid graphene−III−V devices, which could take advantage of the unique properties of these two classes of materials
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