felületállapotok

Surface states, or felületállapotok in Hungarian, refer to the electronic states that are localized at the surface or interface of a material. Unlike bulk states which extend throughout the material, surface states are confined to the outermost atomic layers. These states arise due to the abrupt termination of the crystal lattice at the surface, which breaks the symmetry of the bulk material. This broken symmetry leads to a change in the local atomic environment and potential experienced by electrons at the surface.

The presence of surface states can significantly influence the electronic, optical, and chemical properties of a material. They can introduce new energy levels within the band gap of semiconductors, acting as defect states that can trap charge carriers or facilitate surface reactions. For metals, surface states can affect their catalytic activity and surface conductivity. The nature and energy of these surface states are highly dependent on the specific material, its crystallographic orientation, and any adsorbates or reconstructions present on the surface. Techniques such as scanning tunneling microscopy (STM), photoemission spectroscopy (PES), and low-energy electron diffraction (LEED) are commonly used to investigate and characterize surface states. Understanding and controlling surface states is crucial in various fields, including catalysis, semiconductor device fabrication, and nanoscience.