Short-wavelength, mid- and far-infrared intersubband absorption in nonpolar GaN/Al(Ga)N heterostructures

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 Schrodinger-Poisson calculations. In the near-and mid-infrared regions, we demonstrate m-GaN/Al(Ga) N multi-quantum-wells exhibiting room-temperature intersubband absorption tunable in the range of 1.5-5.8 mu m (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 7-10THz band forbidden to GaAs-based technologies. (C) 2016 The Japan Society of Applied Physics