High current operation of enhancement-mode GaN MIS-HEMTs with triple cap structure using atomic layer deposited Al2O3 gate insulator

In summary, we dem onstrated AlGaN/GaN enhancement-mode MIS-HEMTs that exhibited a high maximum drain current of 860 mA/mm and high off-state breakdown voltage of 320 V with threshold voltage of 3 V by introducing a piezoelectric-induced cap and a recessed ALD-MIS-gate structure. This is the highest Lja¿with the breakdown voltage of over 300 V for enhancement -mode HEMTs. The 1 mm gate width device showed the output power of 4.8 W/mm and high drain efficiency of 61% at the Vgs= 3.8 V. These results suggest that the recessed AlGaN/GaN MIS-HEMT with the triple layer cap could be a promising technique for the Enhancement-mode transistors with a high breakdown voltage.