The MOS device is drived by triangular—voltage sweep which is sufficient todrive the MOS device into the non—equilibrium mode of operation.The C-Vcharacteristic is the function of sweep rate.From the C—V characteristic weanalyse simultaneously minority carrier lifetion (?)_g and surface generation velocity SThe experiment is undertaken on two groups of MOS devices made by the sameoxidation process but the aluminum gates of these two groups of samples weremade by two different methods(the hot filament evaporation and the electronbeam evaporation)in high vacuum evaporation apparatus respectively.The experi-ment shows that the surface generation velocity Sg of the sample with the gateelectrode produced by electron beam evaporation is increased.