Integrated III-V/Si Visible and IR Nanowire Photodetectors

Self-assembled nanowires can support optical resonant modes and act as very effective waveguides that concentrate and absorb light over only a few microns of nanowire length, enabling highly efficient photodetection. The resonant absorption shows wavelength selectivity that can be tuned continuously across the visible and IR wavelengths by adjusting the nanowire diameter during molecular beam epitaxy growth on silicon wafers¹. Thus, ordered arrays of III-V semiconductor nanowires, integrated with standard Si technology, could provide low-cost, high-performance multi-spectral photodetectors.

We realized photodetectors from ordered arrays of InAs (~120 nm diameter) and GaAs (~300 nm diameter) nanowires grown on Si(111) substrates. The nanowires grow out of holes etched into a thin oxide layer down to the Si layer. These holes are lithographically patterned and allow control of the nanowire diameter, pitch and array size, the latter being adjustable down to a single nanowire. The nanowires show a wavelength-dependent response, with a peak centered at ~450 nm for InAs and ~750 nm for GaAs.

1. Rahman et. al., Nanotechnology 26(2015)295202