An A centre in CdTe

Application of electron paramagnetic resonance to neutron-irradiated CdTe shows the presence of a new centre, labelled XA, having mirror symmetry Cs. In terms of a spin Hamiltonian for an effective spin S = 1/2, its g-values are g1 = 2.0034, g2 = 2.0840 and g3 = 2.2020, where axis 1 corresponds to a (110) direction. We show that an A centre consisting of a Cd vacancy and either a group VII donor on a neighbouring Te site or an impurity isoelectronic to Te can account for the observed EPR. In this model, it is assumed that the bound hole of the A centre is distributed among two neighbouring Te ions.