Growth of AlGaN/InGaN/GaN Heterostructure on AlN Template/Sapphire

Abstract

GaN films are grown directly on AlN templates/sapphire substrates without using low‐temperature (LT) buffer layers by metalorganic chemical vapor deposition. AlN templates are complimentarily deformed at the initial growth of GaN, adjusting the a‐lattice constant and tilting crystal orientation slightly. Compared with the film on sapphire substrates using an LT buffer layer, the GaN on the AlN template forms a smoother surface and has better crystalline quality after a shorter growth time at a lower temperature. Higher‐quality InGaN films on the GaN/AlN template are subsequently grown to optimize the thickness exhibiting the minimum Urbach energy which is evaluated by photothermal deflection spectroscopy. A high‐quality AlGaN/InGaN heterostructure is fabricated in which the Shubnikov–de Haas oscillation can be clearly observed from the electron gas of the InGaN channel at the interface.