Suppression of weak localization due to AlN interlayer in AlGaN/GaN 2DEG

Abstract

We have conducted a comprehensive investigation of the magneto-transport properties of Al0.30Ga0.70N/GaN and Al0.30Ga0.70N/AlN/GaN based HEMT structure in terms of inelastic scattering time via weak localization (WL) measurement. Owing to 1 nm AlN interlayer, a small negative-magnetoresistance (MR) effect which appeared over the interval −0.10 T ≤ B⊥ ≤ 0.10 T is further suppressed to −0.040 T ≤ B⊥ ≤ 0.040 T. Using HRXRD measurement and fitting our experimental magnetoresistance (MR) data with theoretical model, it has been analyzed that WL suppression in 2DEG is mainly due to the interlayer while contribution due to crystalline disorder is negligible. Different weak localization parameters like elastic scattering time τe and inelastic scattering time τi are extracted by fitting temperature dependent negative MR data using Hikami-Larkin-Nagaoka (HLN) model. A linear dependence of inelastic scattering rate (τi−1∝ T) with temperature is also observed up to temperature 15 K. Our combined experimental and modeled results demonstrate a significant role of AIN interlayer in suppressing the WL in AlGaN/GaN 2DEG system. Quantitative analysis within the framework of HLN model leads to the conclusion that AlN interlayer break the electronic phase coherence, decrease τi and suppress the localization effect.