Relation of empty surface states to Schottky barriers on semiconductors

Photoemission spectroscopy techniques for measuring occupied and unoccupied semiconductor surface states will be described, including a new yield spectroscopy technique for measuring empty surface states both on clean surfaces and in the presence of a thin metal overlayer (i.e. metal-semiconductor interface). Recent results will be discussed which show that, in general, intrinsic semiconductor surface states (whose energy positions are not simply related to band gap energies} play an important role in determining schottky barrier energies on cleaved