Oxide muonics and the 3-Δ model for deep and shallow hydrogen states in dielectric and semiconducting oxides

In a survey of muonium spectroscopy in some 30 binary oxides, we have discovered 12 new examples of shallow-donor states of the type already known in ZnO, with hints of several others. Their occurrence shows a striking correlation with band-gap. The shallow states are favoured when the gap is less than about 5 eV, whereas only deep atomic states (possibly the neutral states of deep acceptors) occur when the gap is greater than 7eV. Most remarkably, there appears a coexistence of deep and shallow states in the intervening region, 5-7 eV, that will require substantial revision of current theoretical treatments. A parameterized model is proposed to aid understanding of the systematics. Our survey illustrates the potential of the methodology, which we term initonics, to model the electronic structure and electrical activity of hydrogen impurity in new electronic materials. (c) 2005 Elsevier B.V. All rights reserved.