Breakdown Voltage Enhancement In Gan Channel And Algan Channel Hemts Using Large Gate Metal Height

A large gate metal height technique is proposed to enhance breakdown voltage in GaN channel and AlGaN channel high-electron-mobility-transistors (HEMTs). For GaN channel HEMTs with gate-drain spacing L-GD = 2.5 mu m, the breakdown voltage V-BR increases from 518 V to 582 V by increasing gate metal height h from 0.2 mu m to 0.4 mu m. For GaN channel HEMTs with LGD = 7 mu m, V-BR increases from 953 V to 1310 V by increasing h from 0.8 mu m to 1.6 mu m. The breakdown voltage enhancement results from the increase of the gate sidewall capacitance and depletion region extension. For Al0.4Ga0.6N channel HEMT with L-GD = 7 mu m, V-BR increases from 1535 V to 1763 V by increasing h from 0.8 mu m to 1.6 mu m, resulting in a high average breakdown electric field of 2.51 MV/cm. Simulation and analysis indicate that the high gate metal height is an effective method to enhance breakdown voltage in GaN-based HEMTs, and this method can be utilized in all the lateral semiconductor devices.