Charge transport in low-dimensional nitride semiconductor heterostructures

Abstract

Low-dimensional conducting channels in high electron mobility transistors (HEMTs) based on AlGaN/GaN heterostructures have been modeled and the results are described in this paper. The Schroedinger's equation and the Poisson's equation have been solved self-consistently in order to obtain a relationship between the sheet carrier density and the applied gate voltage. The relationship is treated using a non-linear exponential fit that enables a more accurate analysis of the transport saturation region compared to other models used hitherto. The current–voltage ( I– V) characteristics have then been determined by a charge control analysis that utilizes the exponential charge–potential relationship. This identifies the saturation point of channel conduction without parameters extracted from experiments. The intrinsic non-linearity of transport identified by the simulation explains why such devices do not have a singular channel “pinch-off” voltage.