Mechanism of Proton-Induced electrical degradation of AlGaN/GaN high electron mobility transistors

We studied the mechanism of the proton-induced electrical degradation of AlGaN/GaN high electron mobility transistors (HEMTs) through 5-MeV proton irradiation. First, the AlGaN/GaN heterostructure was exposed to protons with a fluence of 1 x 10(15)p/cm(2) to investigate the relationship between the radiation-caused damage in the heterostructure and the electrical characteristics of HEMTs. The HEMTs fabricated on a proton-irradiated AlGaN/GaN heterostructure showed slight degradation in dc characteristics and a positive shift in threshold voltage, compared with the HEMTs fabricated on an unirradiated heterostructure. This indicated that the proton radiation-induced defects in the AlGaN/GaN heterostructure were not dominant factors of characteristic degradation. After additional proton irradiation into both devices, more severe degradation in electrical characteristics was confirmed. The HEMTs fabricated on a proton-irradiated heterostructure showed the largest characteristic degradation in this work. It is expected that the secondary particles, attributed from the collision of proton and metal contacts such as ohmic and schottky, can cause the creation of additional defects, leading to significant degradation of device characteristics. In addition, the pre-existing defects in AlGaN/GaN heterostructures created first proton irradiation can also influence the characteristic degradation of devices.