Band structure of MoS2, MoSe2, and α-MoTe2:: Angle-resolved photoelectron spectroscopy and ab initio calculations -: art. no. 235305

In this work the complete valence-band structure of the molybdenum dichalcogenides MoS2. MoSe2, and alpha -MoTe2, is presented and discussed in comparison. The valence bands have been studied using both angle-resolved photoelectron spectroscopy (ARPES) with synchrotron radiation, as well as ab initio band-structure calculations. The ARPES measurements have been carried out in the constant-final-state (CFS) mode. The results of the calculations show in general very good agreement with the experimentally determined valence-hand structures allowing for a clear identification of the observed features. The dispersion of the valence bands as a function of the perpendicular component (k) over right arrow (1) of the wave vector reveals a decreasing three-dimensional character from MoS2 to alpha -MoTe2 which is attributed to an increasing interlayer distance in the: three compounds. The effect of this (k) over right arrow (1) dispersion on the determination of the exact dispersion of the individual states as a function of (k) over right arrow (parallel to) is discussed. By performing ARPES in the CFS mode the (k) over right arrow (parallel to) component for off-normal emission spectra can be determined. The corresponding (k) over right arrow (1) value is obtained from the symmetry of the spectra alone the GammaA KH, and ML lines, respectively.