Effects of hydrogen implantation into GaN

摘要

Proton implantation in GaN is found to reduce the free carrier density through two mechanisms - first, by creating electron and hole traps at around E_c-0.8 eV and E_v+0.9 eV that lead to compensation in both n- and p-type material, and second, by leading to formation of (AH) deg complexes, where A is any acceptor (Mg, Ca, Zn, Be, Cd). The former mechanism is useful in creating high resistivity regions for device isolation, whereas the latter produces unintentional acceptor passivation that is detrimental to device performance. The strong affinity of hydrogen for acceptors leads to markedly different redistribution behavior for implanted H~+ in n- and p-GaN due to the chemical reaction to form neutral complexes in the latter. The acceptors may be reactivated by simple annealing at >= 600 deg C, or by electron injection at 25-150 deg C that produces debonding of the (AH) deg centers. Implanted hydrogen is also strongly attracted to regions of strain in heterostructure samples during annealing, leading to pile-up at epi-epi and epi-substrate interfaces. IR spectroscopy shows that implanted hydrogen also decorates C_Ga defects in undoped and n_GaN. direct c 1999 Elsevier Science B.V. All rights reserved.