“…The surface-state-induced 2D electron gas (2DEG) on bare surface has been observed in InAs [50] and SrTiO3 [51], [52] has been successfully studied by angle resolved photoelectron spectroscopy (ARPES). Yet, the resulting surface and interface 2DEGs all display similar electronic transport phenomena, suggesting a common underlying electronic structure defined by the properties of material and the crystallographic orientation of the surface or interface.…”