Performance optimization of lateral AlGaN/GaN HEMTs with cap gate on 150-mm silicon substrate

- An innovative gate structure of AlGaN/GaN HEMT called “Cap Gate” is proposed.
- Lower leakage current has been obtained by optimizing gate layout with “Cap Gate”.
- The scaling down LG (with LG + 2LCG constantly) contributes to the on resistance.
- The BV and current capacity of “cap gate” HEMT are also be studied.

A further leakage reduction of AlGaN/GaN HEMTs with cap gate (CG-HEMTs) has been achieved by optimizing the gate structure and the gate etching process. The optimized CG-HEMTs single finger power HEMTs deliver IDSmax = 533 mA/mm at least with gate length of 0.5um and show a median gate leakage current of 20 nA/mm 25 °C measured at a drain voltage of 200 V. The breakdown voltage (BV) of CG-HEMTs was evaluated by the variation of drain-to-gate spacing (LDG) larger than 8 μm. Furthermore, we show that the forward voltage of CG-HEMTs can be improved by shrinking the lateral dimension of the edge termination due to reduced series resistance.

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