Near-infrared intersubband absorption in nonpolar cubic GaN/AlN superlattices

Optical absorption spectra related to intersubband transitions in molecular beam epitaxially grown nonpolar cubic-GaN/AlN superlattices were observed in the spectral range of 1.5-2.00 μm. The background doping was measured using an electrochemical capacitance-voltage technique and found to be on the order of 1018 cm-3. This doping level yields a Fermi energy level slightly above the ground state energy level enabling intersubband transitions to occur. The existence of the intersubband transition is verified in several samples with different well widths. The observed peak position energy of the intersubband transition is compared to those calculated using a transfer matrix method