Short-wavelength, mid- and far-infrared intersubband absorption in nonpolar GaN/Al(Ga)N heterostructures
Résumé
This paper assesses nonpolar m-oriented GaN:Si/Al(Ga)N heterostructures grown on free-standing GaN for intersubband optoelectronics in the
short-wavelength, mid- and far-infrared ranges. Characterization results are compared with reference c-plane samples and interpreted by
correlation with self-consistent Schrödinger–Poisson calculations. In the near- and mid-infrared regions, we demonstrate m-GaN/Al(Ga)N multiquantum-wells
exhibiting room-temperature intersubband absorption tunable in the range of 1.5–5.8 µm (827–214 meV), the long wavelength limit
being set by the second order of the Reststrahlen band in the GaN substrates. Extending the study to the far-infrared region, low-temperature
intersubband transitions in the 1.5–9 THz range (6.3–37.4 meV) are observed in larger m-plane GaN/AlGaN multi-quantum-wells, covering most of
the 7–10 THz band forbidden to GaAs-based technologies.