Electron paramagnetic resonance of nickel in silicon — II. hyperfine and quadrupole interactions

Abstract

An electron paramagnetic resonance (EPR) study on n-type silicon doped with nickel enriched to 88.1% 61Ni is presented. The structure due to the 61Ni isotope with nuclear spin I = 3 2 was investigated. The EPR spectrum with the appearance of “forbidden” lines can be described by a spin Hamiltonian including the nuclear Zeeman, hyperfine and quadrupole interaction terms. A computer calculation of energy levels and transition probabilities of all EPR transitions was made explaining the angular dependence of the magnetic field positions of the resonances and their intensities. The hyperfine tensor A, with principal values A [100] = 1.01 MHz, A [011] = -39.98 MHz and A [01̄1] = -37.60 MHz, is nearly axial around [1 0 0]. An analysis of hyperfine and quadrupole interactions was carried out revealing the specific effect of the nickel impurity on the electronic structure of the centre. Based on the information about spin and charge density as derived in the analysis, a dihedral bonding model for the Si:Ni - s centre is supported.