Transport properties of the two-dimensional electron gas in GaN/AlGaN heterostructures grown by ammonia molecular-beam epitaxy

摘要

Transport properties of the two-dimensional electron gas in AlGaN/GaN heterostructures grown by ammonia molecular-beam epitaxy are experimentally investigated. Conventional Hall and Shubnikov-de Haas measurements as well as investigations of quantum transport phenomena are reported. It is found that negative magnetoresistance (NMR) caused by weak localization demonstrates an unusual behavior at low temperature (1.8 K). The observed NMR cannot be described by the ordinary theory of quantum corrections to conductivity based on a single phase breaking time τ_φ. The anomalous NMR behavior can be explained by the presence of two occupied quantum subbands, characterized by their own phase breaking times τ_(φ1) and τ_(φ2).