A semiconductor device comprises a first transistor with a silicon carbide layer between the source and the drain electrodes and between the gate and drain electrodes. A diode is formed in the silicon carbide layer. A forward voltage of the diode varies with the voltage applied to the gate electrode of the first transistor. A second transistor is connected to the first transistor. A gate controller applies voltages to gates of the first and second transistor such that the first and second transistors are set to an off-state a first time. The first gate voltage is then increased to an intermediate voltage that is less than a threshold voltage of the first transistor. The intermediate voltage is sufficient to alter the forward voltage of the diode and permit a forward current to flow in the diode. The first gate voltage is then increased to an on-state voltage.