Acceptor and donor doping of AlxGa1-xN thin film alloys grown on 6H-SiC(0001) substrates via metalorganic vapor phase epitaxy

Thin films of Si-doped AlxGa1-xN (0.03 less than or equal to x less than or equal to 0.58) having smooth surfaces and strong near-band edge cathodoluminescence were deposited at 0.35-0.5 mu m/h on on-axis 6H-SiC(0001) substrates at 1100 degrees C using a 0.1 mu m AIN buffer layer for electrical isolation. Alloy films having the compositions of Al0.48Ga0.52N and Al0.48Ga0.52N exhibited mobilities of 110 and 14 cm(2)/V.s at carrier concentrations of 9.6 x 10(18) and 5.0 x 10(17) cm(-3), respectively. This marked change was due primarily to charge scattering as a result of the increasing Al concentration in these random alloys. Comparably doped GaN films grown under similar conditions had mobilities between 170 and similar to 350 cm(2)/V.s. Acceptor doping of AlxGa1-xN for x less than or equal to 0.13 was achieved for films deposited at 1100 degrees C. No correlation between the O concentration and p-type electrical behavior was observed.