It was recalled that H passivation, of layers that had been grown onto lattice-mismatched substrates, could produce a thermally stable deactivation of dislocation-related deep levels. It was shown here that H formed complexes with, and deactivated, Zni donor states within Zn-doped samples that were prepared by metal-organic chemical vapor deposition. Deactivation of Zni deep donors, as detected by monitoring the evolution of donor-acceptor transitions using photoluminescence measurements, produced an approximately 50% increase in the net acceptor concentration of heavily Zn-doped hetero-epitaxial material, by eliminating an acceptor compensation effect which was due to active Zni donors. An analysis of current-voltage characteristics indicated that Zni passivation sharply reduced depletion-region recombination in hetero-epitaxial diodes. Subsequent annealing at above 500C re-activated the Zni and tended to restore the original as-grown values. A study of the reactivation kinetics of the H-Zni complex revealed a higher thermal stability than that of H-Zn acceptor complexes but a lower stability than that of H-dislocation complexes. The estimated dissociation energy of the H-Zni complex was 2.3eV. These effects were observed in both homo-epitaxial and hetero-epitaxial Zn-doped layers, but were far more pronounced in hetero-epitaxial layers; due to the relatively high Zni concentration in the latter.

Electrical Deactivation of Interstitial Zn in Heteroepitaxial InP by Hydrogen and its Effect on Electronic Properties. S.A.Ringel, B.Chatterjee: Journal of Applied Physics, 1998, 83[11], 5904-12