LITHIUM PASSIVATION AND ELECTRIC-FIELD-ASSISTED REACTIVATION OF ACCEPTORS IN GAAS

We performed reverse-bias annealing of Schottky diodes on GaAs samples in which Zn and Cu acceptors had been partially passivated by Li diffusion. Using capacitance-voltage and deep level transient spectroscopy measurements we observed thermal dissociation of Zn-Li and Cu-Li complexes in the electric field of reverse-biased junctions and a consequent increase of electrically active acceptors in the depletion region of the diodes as well as enhanced passivation of acceptors in the low-field region of the depletion layer and in the neutral bulk. The direction of the electric field is consistent with lithium drifting as a positively charged ion in p-type GaAs. We also investigated the interaction between lithium and the reactivated acceptors under zero-bias conditions. The effect of zero-bias annealing between room temperature and 150°C on both the shallow Zn and the deep Cu acceptors was found to be consistent with a mobile ionized Lii donor passivating negatively charged acceptors through Coulomb interaction. © 1995 The American Physical Society.