The improvement of breakdown voltage in AlGaN/GaN HEMT by using high-k dielectric La2O3 passivation

The AlGaN/GaN high electron mobility transistor using 30-nm ALD La2O3 passivation has been fabricated. Compared with the non-passivation HEMT, the breakdown voltage Vbr of La2O3 passivation HEMT can be improved from 115 V to 134 V. 2-D simulation is adopted to explain the phenomenon. The reason for enhanced Vbr in La2O3 passivation HEMT is due to high permittivity er of La2O3 dielectric with drain side wall and AlGaN/GaN HEMT can form metal-insulator-semiconductor (MIS) structure which can modulate electric field distribution. Based on the results, the introduction of high-K dielectric passivation can enhance breakdown voltage as well as simplify the process step.