Controlled n -type doping of AlN:Si films grown on 6H-SiC(0001)by plasma-assisted molecular beam epitaxy

We study the properties of Si-doped AlN films grown on 6H-SiC(0001) by plasma-assisted molecular beam epitaxy. Whereas nominally undoped AlN films are invariably insulating in nature, Si-doped films are found to be semiconducting with an electron concentration up to 7.4 × 10 17 cm − 3 , and a resistivity approaching 1 Ωcm at room temperature. Even heavy Si-doping ( 1 × 10 20 cm − 3 ) does not degrade the structural properties of the AlN films. The morphology of these films is characterized by Si-induced step-bunching, but remains smooth with a rms roughness of about 1 nm.