Optical properties of positioned InAs-based nanowire arrays

Small bandgap semiconducting nanowires allow fabricating nanoscale light-sensitive devices like broadband solar cells or mid-infrared (mir) photodetectors. We discuss the optical properties of positioned InAs-based nanowires. To this end, p-Si(111) substrates with a top layer of SiO2 are structured via e-beam lithography by holes with a diameter of approximately 80 nm. The nanowires are then grown vertically on the substrates by solid-source molecular beam epitaxy. The optical properties of the nanowires are characterized by FTIR transmission and angle dependent reflection measurements. To fabricate optoelectronic devices, we subsequently embed the nanowires in an insulator (SiO2 by PECVD and PVD; SOG). After an etch back step, the nanowires are then contacted by depositing a thin conducting layer on top. The p-Si substrate provides the second electronic contact of the optoelectronic two-terminal devices.