High-quality n-type aluminum gallium nitride thin films grown by interrupted deposition and in-situ thermal annealing

High quality Si-doped n-Al0.6Ga0.4N thin films were grown on sapphire substrates by molecular beam epitaxy (MBE) by interrupted deposition and subsequent in-situ thermal annealing (IDTA). High-resolution X-ray diffraction, scanning electron microscope, atomic force microscope, photoluminescence and Hall-effect measurements were carried out to characterize the structural, electrical and optical properties. The results showed that the full width at half-maximum of the Si-doped Al0.6Ga0.4N (0002) was as low as 160 arcsec. The threading dislocation density decreases two orders of magnitude to 6×1107 cm−2 by using the IDTA technology. The carrier density and mobility reached at 1.1×1019 cm−3 and 4.8 cm2/V s, respectively. Si still acted as a shallow donor even for the heavily doped Al0.6Ga0.4N.