Fig. 1. Schematic cross-sectional structure of AlGaN/GaN gate-recessed MIS-HEMT.

Fig. 2. Photomicrograph of (a) MIS-HEMT device and (b) FIB cross-sectional view of gate area.

Fig. 3. Energy band diagram of AlGaN/GaN gate-recessed MIS-HEMT.

Fig. 4. Molecular structure diagram of HfO₂/AlGaN and Al₂O₃/AlGaN interfaces.

Fig. 5. Curves of dielectric layer breakdown voltage of devices.

Fig. 6. Curves of transfer characteristics of recessed MIS-HEMT with (a) 6-nm-thick barrier, (b) 3-nm-thick barrier, and (c) 0-nm-thick barrier, and (d) change trend comparison chart of V_th and G_m.

Fig. 7. The C–V curves of gate-recessed MIS-HEMT.

Fig. 8. Plots of drift mobility versus gate voltage V_g of electron for HfO₂ and Al₂O₃ barriers with different thickness values.

Fig. 9. Pulsed output current curves of devices.

Fig. 10. Comparisons of change trend of R_on and current collapse betwen HfO₂ and Al₂O₃ MIS-HEMTs at maximum gate voltage.