Field-dependent quenching, and sign reversal of the photo-capacitance, were observed in Zn-doped p-type material. These observations were interpreted as being evidence of the self-compensation and metastable properties of the Zn-related center in Si. In order to test this possibility, the effect was considered within the framework of the negative-U concept. It was found that the Zn double-acceptor center exhibited a field-dependent negative-U behavior. A model was proposed that accounted for the properties of the Zn-related center. It was based upon the dependence of the electron-vibration interaction constant, which was governed by linear and quadratic Stark effects upon charge states of the center.

N.T.Bagraev: Solid State Communications, 1995, 95[6], 365-71