A series of GaAs1-ySby epilayers are grown on GaAs substrates under different growth conditions, Different antimony compositions of samples with beryllium doping are obtained.A non-equilibrium thermodynamics model is used to calibrate and fit the Sb composition.Activation energy of 0.37eV for the dissociation process of Sb4 molecules is obtained.Carrier mobility and concentration of samples are influenced by the Sb composition.Quasi-qualitative analysis of mobility is used to explain the relations among Sb composition, carrier mobility and concentration.High resolution x-ray diffraction (HRXRD) rocking curves and Hall effects measurements are used to determine the crystal quality, carrier mobility and concentration.