We present the first clear evidence of electron emission arising directly from a quantized two-dimensional electron channel from the InAs (110) surface covered by a few Cs atoms (≈ 0.01 Cs ML). Spectral features observed by photoemission spectroscopy using synchrotron radiation reveal discrete-energy electronic states resulting from quantization in the direction normal to the surface. The electron photoemission originates from the vicinities of [Formula: see text] points in the first and second surface Brillouin zones corresponding to the bottom of the conduction band. These findings are in agreement with self-consistent theoretical energy-level calculations using a jellium-like model.
Observation of two-dimensional bulk electronic states in the superconducting topological insulator heterostructureCux(PbSe)5(Bi2Se3)6: Implications for unconventional superconductivity