Magnetotransport in Gd-implanted wurtzite GaN Alx Ga1-x N high electron mobility transistor structures

GaN Alx Ga1-x N heterostructures containing a two-dimensional electron gas (2DEG) 27 nm underneath the surface were focused-ion-beam implanted with 300 keV Gd ions at room temperature. At 4.2 K, current-voltage characteristics across implanted rectangles showed that the structures remained conducting up to a Gd dose of 1× 1012 cm-2. Extraordinary Hall effect and anisotropic magnetoresistance were observed at T=4.2 K for structures implanted with 3× 1011 cm-2 Gd. This dose corresponds to a 23% reduction in electron concentration and a decrease in the mobility by a factor of 14 at 4.2 K. However, the still-conducting 2DEG is now embedded in a ferromagnetic semiconductor which opens the possibility to polarize its spins.