Semiconductor surfaces

This chapter discusses the electronic, phononic and atomic behavior at surfaces. Symmetry breaking at the surface causes the emergence of new properties as the state description changes. Starting with an introduction of the semi-classical view, a bulk-based view of workfunction and electron affinity and cautions related to them, toy models are employed to explore the evolution of states at the surface. For electrons, propagating Bloch states persist to the surface but there are also states that are confined. Properties of these confined states and surface states are explored. The implications of stress and of surface reconstruction are discussed to elucidate the atomic rearranging that arises in semiconductors of interest when symmetries change. The state evolution approach is then extended to probe surface phonons. Again, bulk modes persist up to the surface, but there can also be surface-confined modes as well as surface-propagating modes.