Normal Incidence Intersubband Absorption in GaN/AlN Superlattices Grown on Facet-Controlled Epitaxial Lateral Overgrown GaN/Sapphire Templates

Abstract

GaN/AlN superlattice structures along the (1122) facet were grown on facet-controlled epitaxial lateral overgrown (FACELO) GaN/sapphire templates by metal organic chemical vapor deposition (MOCVD). The as-grown GaN/AlN superlattice shows abrupt interfaces and good periodicity, as characterized by high-resolution transmission electron microscopy (TEM). The intersubband transition peak at a wavelength of 1.9 µm was observed for an AlN (1.5 nm)/GaN (1 nm) superlattice grown on the FACELO GaN (1122) facet with the propagation direction of the incident light normal to the (0001) facet of sapphire, called the normal incidence condition. The full width at half-maximum of the absorption peak is as narrow as 65 meV, implying the high quality of the interfaces, good thickness uniformity, and the reduced polarization effect in the structures. This result shows the promising feasibility for realizing two-dimensional (2D) arrays of nitride-based quantum-well infrared photodetectors (QWIPs) using GaN/AlN superlattices grown on FACELO GaN/sapphire templates.