Current transport mechanisms of Schottky barrier (SB) and Modified Schottky barrier (MSB) MOSFETs are investigated by measuring the temperature effect on current-voltage characteristics. For SB MOSFETs, current transport could be dominated by thermionic emission or tunneling mechanism depends on the Schottky barrier height and the gate voltage. The current transport of the MSB MOSFETs changes from tunneling mechanism to drift-diffusion mechanism as the gate voltage increases. The changing point is a good indicator to evaluate the efficiency of the MSB junction. Since the current transport mechanism depends on bias condition, the extraction of mobility should be treated carefully, especially at low gate voltage.