Selective area growth of in-plane InAs nanowires and nanowire networks on Si substrates by molecular-beam epitaxy.

In-plane InAs nanowires and nanowire networks show great potential to be used as building blocks for electronic, optoelectronic and topological quantum devices, and all these applications are keen to grow the InAs materials directly on Si substrates since it may enable nanowire electronic and quantum devices with seamless integration with Si platform. However, almost all the in-plane InAs nanowires and nanowire networks have been realized on substrates of III-V semiconductors. Here, we demonstrate the selective area epitaxial growth of in-plane InAs nanowires and nanowire networks on Si substrates. We find that the selectivity of InAs growth on Si substrates is mainly dependent on the growth temperature, while the morphology of InAs nanowires is closely related to the V/III flux ratio. We examine the cross-sectional shapes and facets of the InAs nanowires grown along the 〈110〉, 〈100〉 and 〈112〉 orientations. Thanks to the non-polar characteristics of Si substrates, the InAs nanowires and nanowire networks exhibit superior symmetry compared to that grown on III-V substrates. The InAs nanowires and nanowire networks are zinc-blende (ZB) crystals, but there are many defects in the nanowires, such as stacking faults, twins and grain boundaries. The crystal quality of InAs nanowires and nanowire networks can be improved by increasing the growth temperature within the growth temperature window. Our work demonstrates the feasibility of selective area epitaxial growth of in-plane InAs nanowires and nanowire networks on Si substrates.