We present the details of growth by metalorganic vapor phase epitaxy and characterization of undoped and Sn doped AlxGa1-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 AlxGa1-xAs grown on GaAs substrates. The photoluminescence efficiency in the Sn-doped AlxGa1-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.