ABSTRACT
Atomic hydrogen plays an important role in GaN, passivating the electrical activity of Mg acceptors during cool-down after metal organic chemical vapor deposition growth, and thereby preventing achievement of high p-type doping levels unless an annealing step is performed. Also hydrogen plays an important role in semiconductors, passivating the electrical activity of shallow and deep level impurities. Unintentional incorporation of hydrogen can therefore lead to uncontrolled variations in the conductivity of a semiconductor, and this effect has been observed for virtually all group IV, III–V and II–VI materials. In other p-type III—IV semiconductors it is generally accepted that the atomic hydrogen is predominantly in a positive charge state with the donor level being around the midgap. If a similar mechanism exists in GaN then the initial Coulombic attraction between ionized acceptor and hydrogen leads to formation of a neutral close pair.
