Metal-Organic Chemical Vapor Deposition of Aluminum Yttrium Nitride

Wurtzite AlN alloyed with group 3 elements Sc and Y boosts the performance of GaN-based high-electron-mobility transistors (HEMTs) significantly as they increase the spontaneous polarization of the barrier layer and, thus, enhance the charge carrier density n(s) in the two-dimensional electron gas (2DEG) formed at the interface with the GaN channel. The emerging nitride Al1-xYxN additionally features an a lattice parameter matching to that of GaN at x = 0.07-0.11, allowing for the growth of strain-free barriers. Here, we demonstrate the growth of Al1-xYxN/GaN heterostructures for HEMTs by metal-organic chemical vapor deposition for the first time. The effect of the Y concentrations on the 2DEG is investigated in a Y concentration range from 3% to 15%. At 8% Y, a record mobility of 3200 cm(2)/(Vs) was measured at a low temperature (7 K). Room and low-temperature n(s) was at 1-2 x 10(13) cm(-2). Al0.92Y0.08N barriers were coherently strained to the GaN channel for barrier thicknesses from 5 to 15 nm. Finally, the deposition of Al1-xYxN/GaN heterostructures deposited on 4 '' 4H-SiC wafers had a room-temperature mobility close to 1400 cm(2)/(Vs). AlYN/GaN heterostructures may offer advantages over AlScN/GaN heterostructures not only for the lower price and higher abundance of the raw material but also in terms of electrical characteristics and may be more suitable for power amplifying applications due to increased electron mobility.