Studies of the Correlation Effect on the Anderson-Localized States in Si:P by the MCSCF Method. I. Uncompensated Case

Abstract

We study the correlation effect on the electronic states in the uncompensated Si:P system from the intermediate to the critical concentration region, by the Multi-Configuration Self Consistent Field (MCSCF) method recently developed by the present authors. By simulating the Si:P system by a cluster model, we clarify the features of the Anderson-localized states and the nature of the metal-insulator transition from a new standpoint. It is shown that most of electrons form spin-singlet pairs and remaining pairs are spin-triplet. Near the metal-insulator transition, MCSCF one-electron orbitals near the Fermi level are extended and the correlation becomes weak by screening. This suggests the Mott-type transition.