Evidence for localized Si-donor state and its metastable properties in AlGaN

Abstract

Transport studies of AlxGa1−xN (0.5<x<0.6) doped with Si have been performed in the pressure range up to 1.4 GPa. For these alloys, the Si dopant forms two donor states. One of them has an effective mass character and the other one represents the localized state strongly coupled to the crystal lattice (metastable state). The localized state of Si forms the corresponding level in the gap for x exceeding 0.5. For the higher x, an increase of the activation energy of this state occurs. Metastable properties of the localized state of Si lead to a persistent photoconductivity effect and to a pressure induced freeze-out of electrons.