Normally-off AlGaN/GaN HFET with p-type GaN Gate and AlGaN Buffer
Int. Symp. on Power Semiconductor Devices & IC's (ISPSD 2010), Hiroshima, Japan, Jun. 6-10, pp. 347-350 (2010).
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A 1.5 A normally-off GaN transistor for power applications in p-type GaN gate technology with a modified epitaxial layer structure is presented. A higher threshold voltage is achieved while keeping the on-state resistance low by using an AlGaN buffer instead of a GaN buffer. Additionally, the AlGaN buffer acts as a back-barrier and suppresses source-drain punch-through currents in the off-state. P-GaN gate GaN transistors with AlGaN buffer will therefore yield higher breakdown voltages as compared to standard GaN buffer versions which results in an excellent VBr-to-RON ratio. The proposed normally-off technology shows save operation under elevated ambient temperature up to 200 °C without thermal runaway. In contrast to standard Schottky-gate AlGaN/GaN HEMTs, a reverse diode operation is possible for off-state conditions which may enable improved inverter circuits.
Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik, Gustav-Kirchhoff-Straße 4, D-12489 Berlin, Germany