Amit Solanki

Vertical germanium nanowires as spectrally-selective absorbers across the visible-to-infrared

Nanostructuring a material permits control over its interaction with light. Advanced methods for controlling the visible-to-infrared absorption spectra of semiconductor materials would present opportunities for photodetectors with engineered spectral response. Here, we experimentally demonstrate the fabrication of arrays of vertical Ge nanowires with different diameters. Measured reflection spectra show dip features for which electromagnetic simulations predict enhanced absorption. These can be shifted to longer wavelengths by increasing the diameters of the nanowires. We show that the reflectance dips broaden if the nanowires exhibit tapering. We furthermore show that observed ripple features in the dips are associated with longitudinal modes of the nanowires.

Germanium Nanowires as Spectrally-selective Photodetectors in the Visible-to-Infrared

We experimentally demonstrate arrays of vertical Ge nanowires as spectrally-selective photodetectors at visible to infrared wavelengths. Measurements reveal that the external quantum efficiency spectra of fabricated devices vary with the radius of the constituent nanowires.

Vertical germanium nanowire photodetectors with suspended graphene top contact

We demonstrate photodetectors for visible-to-infrared imaging, comprising vertical germanium nanowires on a silicon substrate, with a suspended graphene layer as the top electrical contact. Measured responsivity spectra show peaks that shift with increasing nanowire diameter.

Tuning the visible-to-infrared reflectance spectra of arrays of vertical Ge nanowires

We experimentally demonstrate that, by varying their diameter, the visible-to-infrared reflectance spectra of arrays of vertical Ge nanowires can be tuned. The results could enable future nanowire-based photodetectors with tailored responsivity spectra.