Several Abnormal Relaxation Of Wide Band Gap Semiconductor (110) Surface Electronic Structure Theory

In this paper, by using the nearest-neighbor tight-binding sp3s and spd model and Green function method in the frame of the scattering theory, we have studied the (110) surface electronic structure of two semiconductors, HI-nitride BN and I -VII componud CuCI, which have some excelent properties and widespread applications. We have presented the surface projected band structure and the wavevector-resolved layer densities of states at the high-symmetry point in the two-dimensional Brollouin zone. We have discussed in detail the characters of the surface states before and after relaxation. The results show that: (1) The electronic structure of BN (110) surface is qualitatively similar to those of (110) surface of most rn-v and II -VI compounds. But there are relatively large differences of surface states in energy level, dispersion and orbitial. One of the obvious differences is that although the ation-drived and cation-drived dangling bond states in the gap have shifted up and down respctively after relaxation, part of them is still in the gap. This is completely different from the general conclusion of 揜elaxation have drived the surface states out of the gap.?(2) The changes of the eletronic structure of CuCl (110) surface after relxation is mainly due to the rehybridization between Cu-d electrons and Cl-p electrons. The mechanism for the relaxation is that the rehybridization of both p-p and p-d electrons in the top two layers plays an important part in the surface relaxation while the rehybridization of only the p-p electrons plays an important role in the (110) surface relaxation of most Ill-V and IJ-VI compounds.