The effective radii of donors (interstitial Na) and acceptors (Na on a Zn substitutional site) were determined for Na-doped material. The radii were deduced from the time decay of relatively close pairs. It was suggested that previous determinations of such impurity radii, which generally considered the decay of the distant-pair peak, were usually inaccurate due to the neglect of excitation transfer. The effect of such transfer was minimized by the use of the decay of close pairs. The present results agreed closely with the values which were deduced by using scaled effective-mass theory.

G.J.Yi, G.F.Neumark: Physical Review B, 1993, 48[23], 17043-5