(Invited) Effect of Annealing on Electronic Carrier Transport Properties of Gamma-Irradiated AlGaN/GaN High Electron Mobility Transistors
We found the relationship between dose, diffusion length and its activation energy after gamma-irradiation and after annealing treatment. Temperature dependent EBIC measurements yielded a decrease in diffusion length with corresponding increase in activation energy after the gamma-irradiation.The increase in activation energy is likely an indication of the creation of deeper gamma irradiation induced defect traps due to nitrogen vacancies. These deep traps reduce the carrier concentration and mobility and increase the activation energy related to carrier recombination. It is evident from our results that annealing of HEMTs that were gamma-irradiated with moderate dose leads to the recovery (depending on dose) of minority carrier diffusion length. The recovery is also reflected in the activation energy returning to its pre-irradiated value. The level of recovery of gamma-irradiated devices after annealing treatment depends on the dose of irradiation. Increase in diffusion length after annealing had been attributed to a reduction in point defects (nitrogen vacancies) induced in AlGaN/GaN by gamma-irradiation.