Termination-dependent surface properties in the giant-Rashba semiconductorsBiTeX(X=Cl, Br, I)

The noncentrosymmetric semiconductors $\mathrm{BiTe}X\phantom{\rule{4pt}{0ex}}(X=\text{Cl},\text{Br},\text{I})$ show large Rashba-type spin-orbit splittings in their electronic structure making them candidate materials for spin-based electronics. However, BiTeI(0001) single-crystal surfaces usually consist of stacking-fault-induced domains of Te and I terminations implying a spatially inhomogeneous electronic structure. Here we combine scanning tunneling microscopy, photoelectron spectroscopy (ARPES, XPS), and density functional theory calculations to systematically investigate the structural and electronic properties of $\mathrm{BiTe}X(0001)$ surfaces. For $X=\text{Cl}$, Br we observe macroscopic single-terminated surfaces. We discuss chemical characteristics among the three materials in terms of bonding character, surface electronic structure, and surface morphology.