Silicon Doping Dependence of n-Type Al0.5Ga0.5N Layers Grown by Metalorganic Chemical Vapor Deposition

摘要

The electrical, structure and optical properties of Si-doped Al0.5Ga0.5N epilayers with a thickness of about 0.5 μm grown on sapphire substrates using an AlN buffer by metalorganic chemical vapor deposition were reported. Hall-effect measurements showed that n-type Al0.5Ga0.5N was achieved achieved with an electron concentration of 1.2 × 1019 cm-3 and mobility of 12 cm2· Vs- 1 at room temperature. The electron concentration increases with an increase of Si doping level. Lattice constant of c and Raman shift of Si-doped Al0.5Ga0.5N epilayers with various SiH4 flow rates was studied by Xray diffraction (XRD) and Raman scattering spectrum. With increasing SiH4 flow rate, the decrease of the lattice constant of c and the frequency of E2 phonon implies gradual relaxation of the stress in the epilayers.