Is high-T c superconductor an undegenerated doped semiconductor?

Abstract

The model of electron spectrum of HTS is suggested. It is supposed that the main feature of the spectrum is the presence of a narrow local pair level placed near the top of the filled two-dimensional (2D) electron band. Holes in this band are the result of thermal activation of electrons from the band to the pair level. The temperature dependences of resistivity and Hall constant of HTS in this model are in agreement with experiment on YBCO. The possibility of a first-order phase transition in such a system is considered.