The strong correlation of the 4f electrons of erbium in silicon

Abstract

The local spin density approximation (LSDA) with the Hubbard modelcorrection is adopted to describe the electronic structures of O-codopedEr–Si systems. The electrons in the 4f orbitals of Er atoms are taken aslocalized electrons in the framework of an all-electron treatment. Thetotal density of states (DOS) and the partial densities of states forSi(3s, 3p), Er(4f), Er(5d), Er(6s), O(2s), and O(2p) in this ErSiOsystem are calculated. It is found that the inclusion of the HubbardUgreatly influences the partial DOS of the Er 4f electrons. The separation betweenthe spin-up and the spin-down states of the highly localized 4f orbitals is largerthan that of the LSDA results obtained without considering the HubbardU-parameter.The calculation results provide possible explanations of the experimentallyobserved erbium-induced impurity energy levels in Si detected by deep-leveltransient spectroscopy.