Improvement of Breakdown Voltage and ON-Resistance in Normally-OFF AlGaN/GaN HEMTs Using Etching-Free p-GaN Stripe Array Gate

In this article, the normally-OFF etching-free p-GaN stripe array gate AlGaN/GaN high-electron-mobility-transistors (PSAG-HEMTs) are designed and experimentally demonstrated through hydrogen plasma treatment. The unique threshold voltage (V-TH) modulation technique based on the PSAG structure is proposed and simulated. Using this method, the V-TH can be continuously shifted from -0.14 to +1.03 V by just tuning the widths of p-GaN (Wp) and hydrogenatedp-GaN (HR-GaN) stripes. To improve breakdown voltage (BV), the PSAG is extended to the drain side based on the 3-D simulation results so that a new electric-field peak is introduced at the edge of the PSAG in the drain side and then the surface electricfield is optimized. Besides this, an enhanced conductivity effect is observed and results in a low ON-resistance. The fabricated PSAG-HEMT with 0.75 mu m W-p and 4-mu m extension length (L-E) exhibits a positive V-TH of +0.8 V, a low-specific ON-resistance (R-ON,R- sp) of 2.73 m Omega.cm(2), a high BV of 852 V (1449 V) at I-D = 1 mu A/mm, and BFOM of 266 MW/cm(2) (769 MW/cm(2)) with substrate grounded (floating), which demonstrate significant improvements over Reference single-gate E-mode and D-mode devices. This work provides a promising architecture for future high voltage normally-OFF p-GaN HEMT devices.

Automated summary

In this article, normally-OFF etching-free p-GaN stripe array gate AlGaN/GaN high-electron-mobility-transistors (PSAG-HEMTs) are designed and experimentally demonstrated through hydrogen plasma treatment. A unique threshold voltage modulation technique is proposed based on the PSAG structure, allowing continuous V-TH shift by tuning the widths of p-GaN and hydrogenatedp-GaN stripes. By extending the PSAG to the drain side based on 3-D simulation results, improvements in breakdown voltage and enhanced conductivity effect are observed, resulting in a low ON-resistance. The fabricated PSAG-HEMT exhibits significant improvements over Reference single-gate E-mode and D-mode devices, showcasing a promising architecture for future high voltage normally-OFF p-GaN HEMT devices.