Single and pair electronic states in amorphous semiconductors

The interaction of two level tunneling modes (appearing in certain amorphous semiconductors) with electrons and holes is studied theoretically. An electron or a hole can be localized in the vicinity of a tunneling mode. A tunneling mode can also mediate an electron-electron or hole-hole attraction which can give rise to an electron or hole pair localized in the vicinity of this tunneling mode. Furthermore, resonance states can be created near the band edges. These electronic states provide a qualitative or semiquantitative explanation for numerous experimentally observed properties.