Zn-related center in silicon : negative- U properties

(Received 10 June 1992, accepted 26 June 1992)

Abstract
Photo-EPR and Stark effect photocapacitance investigations of ⁶⁷Zn-doped silicon have yielded an orthorhombic Zn-related center whose presence can only be observed under impurity light illumination. The spectral dependences of regeneration and quenching obtained for the EPR signal and photocapacitance at different values of anisotropic electric field reveal the negative- U ordering for the center's acceptor levels, with the ( 0/-) level lying above the (-/--) level. The negative- U properties of the center and the resonant nature of its and optical transitions are modelled in terms of the tunneling performed by the reconstructed deep defect between the D , C and C symmetry positions corresponding, to D ⁰, paramagnetic D ^- and D ^- states, respectively.