Transport properties of polarization-induced 2D electron gases in epitaxial AlScN/GaN heterojunctions

AlScN is attractive as a lattice-matched epitaxial barrier layer for incorporation in GaN high electron mobility transistors due to its large dielectric constant and polarization. The transport properties of polarization-induced two-dimensional (2D) electron gas of densities of similar to 2 x 10(13)/cm(2) formed at the AIScN-GaN interface is studied by Hall-effect measurements down to cryogenic temperatures. The 2D electron gas densities exhibit mobilities limited to similar to 300 cm(2)/V s down to 10 K at AlScN/GaN heterojunctions. The insertion of a nm AlN inter-layer boosts the room temperature mobility by more than five times from similar to 300 cm /V s to similar to 4573 cm(2)/V s, and the 10 K mobility by more than 20 times to similar to 6980 cm(2)/V s at 10 K. These measurements provide guidelines to the limits of electron conductivities of these highly polar heterostructures. Published under an exclusive license by AIP Publishing.