The Simulation Study of Ohmic Contact at GaN- HEMT Devices Based on TCAD

AlGaN/GaN high-electron-mobility transistors (HEMTs) are power devices with high switching frequency, high operating temperature and voltage due to the remarkable materials performance of GaN, which is expected to replace silicon based or silicon carbide devices in low- and medium- voltage applications. However, in order to obtain low-loss and high-frequency performance of these devices, the formation of source and drain ohmic contacts with low contact resistance is vital. In this work, the influence of trap and self-heating effects on the contact resistance simulations with various trap density, trap energy level and external temperature has been investigated by SILVACO-ATLAS software tool. The results show that the contact resistance augments with the increase of the interface trap density and the high bulk trap density has a great influence on the device performance, but the effects of the trap level can be omitted. In addition, with the increase of temperature, the emission current of thermionic in the electrode area will go up, thus reducing the contact resistance. However, high temperature will limit other performance of the device and deteriorate the reliability.