Transistor devices are provided. A transistor device includes a unipolar transistor coupled between a first terminal and a second terminal; and a bipolar transistor coupled in parallel to the unipolar transistor between the first terminal and the second terminal. The bipolar transistor is configured to carry a majority of a current flowing through the transistor device when at least one of the current or a control voltage controlling the unipolar transistor and the bipolar transistor exceeds a predetermined threshold. The bipolar transistor is further configured to have a threshold voltage higher than a threshold voltage of the unipolar transistor, and a difference between the threshold voltage of the bipolar transistor and the threshold voltage of the unipolar transistor is at least 1 V.