Study of drain induced channel effects in vertical GaN junction field-effect transistors

In this work, a normally-off vertical gallium nitride (GaN) junction field-effect transistor (JFET) was demonstrated. The device shows a current on/off ratio of 3.6×10^10, a threshold voltage (VTH) of 1.64 V and a specific on-resistance (RON,SP) of 1.87 mΩ·cm^2. Drain induced channel effects were proposed to explain the change of gate current at different drain voltages. Drain current decline in the output characteristics and the reverse turn-on between drain and source can be explained by the effects. Technology computer aided design (TCAD) was used to simulate the change of the depletion region and confirm the explanation. Detailed analyses of the channel effects provide a reference for the design of new structures. The characteristics at different temperatures were demonstrated to show the stability of threshold voltage and specific on-resistance, which indicates the great potential of application in switching power circuit of vertical GaN JFETs.