High Uniformity Normally-OFF p-GaN Gate HEMT Using Self-Terminated Digital Etching Technique

A normally-OFF p-GaN gate AlGaN/GaN high-electron-mobility transistor with high ON-state resistance ( ${R}_{ \mathrm{\scriptscriptstyle ON}}$ ) uniformity was realized using a self-terminated digital etching technique. ${R}_{ \mathrm{\scriptscriptstyle ON}}$ uniformity control was improved by simultaneously using an AlN etching stop layer in an epitaxial design and a novel digital etching procedure. Digital etching includes the multiple-cycle oxidation and the wet etching of p-GaN layers and provides easy control of p-GaN removal depth and surface damage reduction at the gate-to-drain and gate-to-source spacing areas. Low-frequency noise and pulse measurements indicated that device surface traps and current collapse phenomena were suppressed.