Experimental surface electronic band structure of the (101¯0) surfaces of CdS and CdSe

The band structure of surface electronic states on the (101¯0) cleavage surfaces of the wurtzite II-VI semiconductors CdS and CdSe has been studied experimentally. With the use of synchrotron radiation excited angle-resolved ultraviolet photoelectron spectroscopy, the surface electronic band structures have been investigated along the high-symmetry directions in the surface Brillouin zone (BZ). Through the observation of structures with two-dimensional dependence on the wave vector k, i.e., showing no dispersion with the perpendicular component of k within a direct transition model, two surface resonances on each of the studied surfaces have been identified. Their energy dispersions along the boundary of the respective surface BZ and the polarization dependence of the uppermost resonances, $S_1$ and $S_1^{\mathcal{’}}$, are presented. By comparing the results with a recent calculation for ZnS by Wang and Duke, conclusions about the relaxation of the surfaces are made.