Infrared Absorption at 300 K in InGaN/GaN Disk-in-Nanowire Arrays Grown on (001) Silicon

In 0.34 Ga 0.66 N/GaN disk-in-nanowire arrays have been grown on (001) Si substrates by molecular beam epitaxy and their infrared absorption spectra have been measured at room temperature. The average diameter and area density of the nanowires are 60 nm and $2\times 10^{10}$ cm $^{-2}$ , respectively. The room temperature photoluminescence spectrum is characterized by peak emission at 540 nm. The absorption spectra measured with a Fourier transform infrared spectrometer in transmission and reflection modes exhibit multiple absorption peaks ranging from 1.6 to $20~\mu \text{m}$ . The peak energies have been compared with those for intersubband transitions calculated with a simple model and there is agreement in some cases.