Effect of Double Insulators on the Performance Improvement of 3 MeV Proton-Irradiated AlGaN/GaN MIS-HEMTs

To improve the performance of AlGaN/GaN high electron mobility transistors (HEMTs) after exposure to high energy proton irradiation, a MIS-HEMT with Al2O3/SiNx (SiNx next to semiconductor) double insulators is proposed and fabricated. Besides, the common Schottky gate HEMT and MISHEMTs with single SiNx layer and single Al2O3 layer are also fabricated as a control for comparison. After exposed to 3 MeV proton irradiation with a fluence of 1 x 10(14)cm(-2), the MIS-HEMT with Al2O3/SiNx double insulators shows the smallest drain saturation current and breakdown voltage degradation, the smallest voltage drift and interface charge change through IV and CV tests. The smallest degradation of the carrier density and mobility contributes to its better saturation current degradation performance. Besides, experimental results of voltage drift are in accordance with simulation results. What's more, the MIS-HEMT with Al2O3/SiNx double insulators exhibits the lowest drain current degradation and the quickest response during hard switching tests. A relatively large displacement threshold energy of Al2O3 and better passivation effect of SiNx contribute to the reliability improvement of AlGaN/GaN HEMTs after the proton-irradiation.