Enhanced performance of normally-OFF GaN HEMTs with stair-shaped p-GaN cap layer

Abstract

The p-GaN-gated E-mode HEMTs (P-HEMTs) are being extensively studied for emerging power electronics. However, the devices still suffer from performance trade-off among threshold voltage (V TH), output drain current (I DS), and breakdown voltage (V BD). Herein, we propose a P-HEMT with a stair-like p-GaN cap layer to boost their performance. The p-GaN cap layer is composed of four discrete p-GaN staircases with the decreased thickness to the right (Right-Stair P-HEMT) or to the left (Left-Stair P-HEMT). It is found that the RSP-HEMT simultaneously achieves the 1.3 times increased I DS, 160 V enhanced V BD, and improved V TH stability against drain-induced barrier lowering effects, compared with the LSP-HEMT and the conventional BaSeline P-HEMT. These device merits should be attributed to the effective manipulation of the lateral electric field (E F) under all bias conditions by the unique band structures enabled by the RSP configuration. Such E F manipulation strategies offer us helpful guidance and insights to further propel the development of high-performance E-mode P-HEMTs.