Optimization of electric field distribution for AlGaN/GaN MIS-HEMT with thick i-GaN cap layer

The significant optimization of electric field distribution for AlGaN/GaN metal-insulator-semiconductor high electron mobility transistor (MIS-HEMT) with a thick i-GaN cap layer is reported. The thick i-GaN cap layer is introduced to generate two-dimensional hole gas (2DHG), thereby reducing the electron concentration in the two-dimensional electron gas (2DEG) layer under off-state, in contrast to the high electron concentration in the 2DEG layer under off-state for the MIS-HEMT with a p-type or insulating passivation layer. Due to the low electron concentration in the 2DEG layer and the introduction of the thick i-GaN cap layer, a wide depletion region forms in this cap layer just close to the drain electrode under off-state, resulting in a low electric field intensity both in the whole access region and in the region close to the gate. Thus, the adverse effect induced by the high electric field strength under off-state, such as the large dynamic on-resistance (Ron), is significantly mitigated.