ABSTRACT
At variance with the mechanisms responsible for the passivation of
typical shallow dopants in GaAs, where H bonding with the impurity
or to its neighbors permits a recovery of the “natural” chemical
valence of the impurity itself, in the case of the N isoelectronic
impurity in GaAs, H induces no changes in the N chemical valence.
It breaks, instead, two Ga-N bonds to form complexes sharing a
common, quite stable NH2 core characterized by a local C2v-like
symmetry, thus strongly perturbing the interactions of N with its
four Ga neighbors. A theoretical picture is presented here, where
the N effects on the GaAs electronic properties, as well as their
passivation upon hydrogenation, are closely related to the local N-
Ga interactions and to the perturbations induced by H bonding on
the N environment. The formation of multi-H complexes with N,
predicted by theory, is also discussed together with the support
given to their existence by recent experimental findings.
