Enhanced Performance of Normally-OFF GaN HEMTs with Stair-shaped p-GaN Cap Layer

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 ( R ight- S tair P -HEMT) or to the left ( L eft- S tair 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 B a S eline 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.