ABSTRACT

GaN is of increasing interest for high-temperature and high-power applications. Various electronic devices based on GaN have already been reported. Recently, implantation­ doping of GaN has become a practical option when designing electronic devices, with selective-area doping being of particular interest. Several n-and p-type implantation techniques have already been reported for GaN, with Si [1-6] being the main dopant for n-type material and Mg [2,5,7] and Ca [1,8] the most common elements implanted for p-type doping. Theory suggests that those dopants occupying a Ga-lattice site in GaN will have a low formation energy and will form donor or acceptor energy levels. However, in the case of conventional implantation, where only one kind of dopant is used, the generation of many N-vacancies and self-compensation induced by site­ switching may occur in the implanted region after the activation annealing process. Therefore, in order to suppress the generation of N-vacancies, a N-rich condition needs to be created prior to implantation of the dopant atoms, and so the implantation of additional N atoms into the GaN might be expected to increase the probability of the particular dopant atoms occupying a Ga-lattice site [9,10]. Here, we propose sequential co-implantation of N atoms and the dopant, based on the site competition effect. In this study, we have selected Ge as a new n-type dopant for GaN and investigated Ge doping

characteristics and structural defects in N/Ge co-implanted and subsequently annealed GaN.