Thermal broadening of two-dimensional electron gas mobility distribution in AlGaN/AlN/GaN heterostructures

Two-dimensional electron gas (2DEG) transport in Al_0.3Ga_0.7N/AlN/GaN heterostructures has been studied using magnetic-field dependent Hall-effect measurements and advanced mobility spectrum analysis techniques over the temperature range from 95 K to 300 K. It is shown that electronic transport is due to a single well-defined 2DEG species, with room-temperature sheet concentration and average mobility of 9.3 × 10¹² cm^-2 and 1,880 cm²/Vs, respectively. No parasitic conduction through the bulk GaN layer was detected. Importantly, it is shown that the 2DEG exhibits an approximately Gaussian mobility distribution, the linewidth of which broadens with increasing temperature. This is the first reported observation of thermal broadening effects in the 2DEG mobility distribution.