Vertical Ge-Si Nanowires with Suspended Graphene Top Contacts as Dynamically Tunable Multispectral Photodetectors

Abstract

Numerous applications would be enabled by pixels for multispectral imaging whose spectral responses can be dynamically tuned and that can be potentially manufactured at low cost. Here, we show such a capability, by experimentally demonstrating arrays of vertically oriented germanium–silicon heterojunction nanowires with graphene top contacts. Our devices present opportunities for multispectral imaging because their responsivity spectra can be tailored by choice of nanowire radius for enhanced absorption at certain wavelengths across the visible to short-wave infrared. Importantly, these responsivity spectra can also be dynamically tuned by bias voltage. We demonstrate this experimentally by ..