Drain E-field manipulation in AlGaN/GaN HEMTs by Schottky extension technology

Abstract

The proposed hybrid Schottky-ohmic drain structure is analyzed in detail for AlGaN/GaN power high-electron mobility transistors on the Si substrate. Without any additional photomasks and process steps, the hybrid drain design can alter the electric field distribution to improve the breakdown voltage VBK. In addition, it provides an additional current path to achieve zero onset voltage and reduce the ON-resistance. It was found that the Schottky extension Lext is critical to VBK, RON, and also the current collapse phenomena of the transistors. The extended Schottky electrodes for optimized transistor characteristics are investigated, and the physics behind are discussed. With an Lext ̃ 2-3 μm, VBK can be improved up to 60% with an RON degradation below 3%.