C. Mietze

Band offset between cubic GaN and AlN from intra‐ and interband spectroscopy of superlattices

By the analysis of intra‐ and intersubband transitions in GaN/AlN superlattices the band offset is determined experimentally. Superlattice structures with different period lengths were fabricated by plasma‐assisted molecular beam epitaxy 3C‐SiC substrates. The structural properties were studied by high resolution X‐ray diffraction, revealing a high structural perfection of the superlattice region with several peaks in the X‐ray spectra. Infrared absorbance spectroscopy revealed clear intrasubband transitions in the spectral region of 1.55 μm measured at room temperature. Clear intersubband transitions were observed by photoluminescence at room temperature. These transition energies were compared to calculated energies using a 1D Poisson Schrodinger solver. For the calculations standard parameters for cubic GaN and AlN were used, while the band offset between GaN and AlN was varied. Optimal agreement between experimental and theoretical data was obtained for a band offset ΔEC:Δ EV of 55:45.