Topological Aspects of Surface States in Semiconductors

Topological aspects of surface states in semiconductors are studied by an adiabatic deformation which connects a realistic system and a decoupled covalent-bond model. Two topological invariants are focused. One is a quantized Berry phase, and the other is a number of the edge states. A winding number as another topological invariant is also considered. The surface states of Si and Ge at (111), (110), and (100) surfaces are classified by the topological invariants. Surface states of the GaAs as heterosemiconductors are also discussed.