Experimental Identification of Atomic Orbital Contributions to SnS Valence Band using Polarization-Dependent Angle-Resolved Photoemission Spectroscopy

Angle-resolved photoemission spectroscopy (ARPES) is performed on single-crystalline tin(II) sulfide (SnS) over a wide energy range (from Fermi level to -10 eV) using four measurement geometries with different excitation light polarizations and sample rotation angles. Based on the different symmetries of the atomic orbitals with respect to the mirror plane, the contribution of each atomic orbital of the constituent elements to the SnS valence band is determined. The results obtained agree with those of first-principles calculations. Experimental results indicate that at the top of the valence band, the S 3p(y) and 3p(z) contributions are strong near the Z and Gamma points, respectively. Meanwhile, in the same region, the S 3p(x) contribution is minimal and is concentrated at -2 eV lower than that of the valence band maximum. Although ARPES measurements are performed at different geometries, direct comparisons of the obtained measurements with calculation results are rarely conducted over such a wide energy range. This study is an effective example of experimental identification of the electronic band structures.