InN Nanowires on Si⟨111⟩ and Si⟨100⟩ for Monolithic Short-Wave Infrared (SWIR) Photodetectors

Abstract InN nanowires were grown on Si⟨111⟩ and Si⟨100⟩ substrates by plasma-assisted molecular beam epitaxy using a thin AlN buffer layer at temperatures compatible with the thermal budget limitation imposed by back-end-of-line processing. Reflection high-energy electron diffraction reveals differences in the AlN nucleation on the two substrate orientations, with higher structural disorder in the case of Si⟨100⟩. However, vertically aligned nanowires with a hexagonal cross section and N polarity are obtained on both substrates. A statistical analysis of nanowire morphology as a function of growth temperature indicates similar trends (increasing diameter and length, and decreasing density with increasing temperature) on Si⟨111⟩ and Si⟨100⟩, which are explained by adatom kinetics during growth. Nanowires on Si⟨100⟩ exhibit improved uniformity and reduced tapering, attributed to the different nanowire nucleation due to microstructural properties of the AlN buffer layer. The results demonstrate the feasibility of growing high-quality InN nanowires on Si⟨100⟩, supporting their potential for monolithic integration of nanowire-based photodetectors on silicon.