Properties of Al_xGa_1-xAs with an AlAs buffer layer on Si substrates grown by metalorganic vapor phase epitaxy

We present the details of growth by metalorganic vapor phase epitaxy and characterization of undoped and Sn doped Al_xGa_1-xAs (0≤ x ≤ 0.3) on Si substrates with AlAs buffer layer. Double X-ray diffraction has been performed on these samples and the estimated dislocation density is in the order of 8x10⁶ cm^-2. The carrier concentration in these samples were obtained by Schubnikov-De Haas effect and the observed oscillations compare very well with the Al_xGa_1-xAs grown on GaAs substrates. The photoluminescence efficiency in the Sn-doped Al_xGa_1-xAs/Si sample is about 640 times greater than in the undoped one and this is attributed to annihilation of non-radiative centers by Sn atoms. The biaxial stress in these films is estimated from the peak positions in the photoluminescence spectra measured as a function of temperature.