The geometric and electronic properties of the PbS, PbSe and PbTe (0 0 1) surfaces

The geometric and electronic structures of the PbS, PbSe and PbTe(0 0 1) surfaces were investigated by using the density functional theory. The calculations show that the (0 0 1) surfaces of these semiconductors do not reconstruct but exhibit oscillatory geometric relaxation to some extent. The interlayer distance shift and the intralayer rumpling have some obvious regularity. The calculations also show that the electronic structures of these semiconductors are very similar. The direct surface band gap locates at the X point and there are no new surface states appearing in the fundamental band gap. Some p characters surface resonance states appear mainly in the valence and the conduction band, and the other surface state with the anions s character also appears in the deep band gap below −10.0 eV.