Electrical measurements of an AlGaN/GaN high-electron-mobility transistor structure grown on Si

We report on magnetotransport results for an Al _{0. 15}Ga _{0. 85}N/GaN high-electron-mobility-transistor structure grown on a p-type Si (111) substrate. Our results show that there exists an approximately temperature (T)-independent point, which could be ascribed to a direct transition from a weak insulator to a high Landau level filling factor quantum Hall state, exists in the longitudinal resistivity ρ _xx. The Hall resistivity decreases with increasing T, compelling experimental evidence for electron-electron interaction effects in a weakly-disordered two-dimensional (2D) system. We find that electron-electron interaction effects can be estimated and eliminated, giving rise to a corrected nominally temperature-independent Hall slope. By fitting the low-field magnetotransport data to conventional 2D weak localization theory, we find that the dephasing rate 1/τ _φ{symbol} is proportional to T. Moreover, 1/τ _φ{symbol} is finite as T → 0, evidence for zero-temperature dephasing in our system.