Effects of hydrogen implantation into GaN

Proton implantation in GaN is found to reduce the free carrier density thro ugh 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-typ e material, and second, by leading to formation of (AH)degrees complexes, w here A is any acceptor (Mg, Ca, Zn, Be, Cd). The former mechanism is useful in creating high resistivity regions for device isolation, whereas the lat ter produces unintentional acceptor passivation that is detrimental to devi ce performance. The strong affinity of hydrogen for accepters leads to mark edly different redistribution behavior for implanted H+ in n- and p-GaN due to the chemical reaction to form neutral complexes in the latter. The acce pters may be reactivated by simple annealing at greater than or equal to 60 0 degrees C, or by electron injection at 25-150 degrees C that produces deb onding of the (AH)degrees centers. Implanted hydrogen is also strongly attr acted to regions of strain in heterostructure samples during annealing, lea ding to pile-up at epi-epi and epi-substrate interfaces. IR spectroscopy sh ows that implanted hydrogen also decorates V-Ga defects in undoped and n-Ga N, (C) 1999 Elsevier Science B.V. All rights reserved.