Effect of Hydrogen on Radiation-Induced Displacement Damage in AlGaN/GaN HEMTs

To explore the role of hydrogen in radiation degradation of AlGaN/GaN high-electron-mobility transistors (HEMTs), the performance degradation of the hydrogen untreated and pretreated devices is compared under the exposure of carbon ions. The energy of carbon ions is chosen as 7.6 MeV, and the maximum fluence reaches 4 x 10(12) cm(-2). By electrical character measuring, it is found that the positive shift of the threshold voltage and the decrease of the transconductance occur after to the irradiation. Hydrogen pretreatment accelerates the shift of threshold voltage and the decrease of the transconductance. The threshold voltage of the device is almost unchanged under 1-MeV electron irradiations. This means that the displacement damage leads to the shift of the threshold voltage. The height of Schottky barrier hardly changes in the hydrogen pretreated devices, showing that the ionization defects such as the formation of interface states under the gate are not the main cause of device degradation. Deep level transient spectrum (DLTS) results show that the irradiations cause the increase of gallium vacancies, and the hydrogen pretreatment inhibits its formation. According to the first principle calculation, the existence of hydrogen in GaN layer can reduce the formation energy of and the number of charges of the defects. It is speculated that hydrogen atoms participate in the evolution of radiation defects, which changes the types and number of defects in the devices.

Automated summary

The role of hydrogen in radiation degradation of AlGaN/GaN HEMTs was explored by comparing the performance of hydrogen untreated and pretreated devices under exposure to carbon ions. The experiments showed that hydrogen pretreatment accelerated the shift of threshold voltage and the decrease of transconductance, while also inhibiting the formation of gallium vacancies. Additionally, first principle calculations indicated that the presence of hydrogen in the GaN layer reduced the formation energy of defects, suggesting that hydrogen atoms participate in the evolution of radiation defects in the devices.