Very low sheet resistance and Shubnikov-de-Haas oscillations in two-dimensional electron gases at ultrathin binary AlNGaN heterojunctions

Abstract

Very low sheet resistance two-dimensional electron gases have been obtained at ultrathin AlNGaN heterojunctions. By investigating the molecular beam epitaxy growth conditions, the interface roughness at the heterojunction has been reduced, leading to high room-temperature electron mobilities (μ∼1400-1600 cm2 V s) and high electron sheet densities due to spontaneous and piezoelectric polarization (ns ∼1-3× 1013 cm-2) depending on the AlN thickness. This combination led to a large reduction of the room-temperature sheet resistance of 148 , a new record. The improved transport properties have made it possible to observe Shubnikov-de-Haas oscillations of the magnetoresistance of the two-dimensional electron gas at ultrathin binary AlNGaN heterojunctions for the first time. The results are indicative of the vast potential of high-quality AlNGaN structures for a variety of device applications. © 2008 American Institute of Physics.