8. Electronic Properties of Semiconductor Interfaces

In this chapter we investigate the electronic properties of semiconductor interfaces. Semiconductor devices contain metal–semiconductor, insulator–semiconductor, insulator–metal and/or semiconductor–semiconductor interfaces. The electronic properties of these interfaces determine the characteristics of the device. The band structure lineup at all these interfaces is determined by one unifying concept, the continuum of interface-induced gap states (IFIGS). These intrinsic interface states are the wavefunction tails of electron states that overlap the fundamental band gap of a semiconductor at the interface; in other words they are caused by the quantum-mechanical tunneling effect. IFIGS theory quantitatively explains the experimental barrier heights of well-characterized metal–semiconductor or Schottky contacts as well as the valence-band offsets of semiconductor–semiconductor interfaces or semiconductor heterostructures. Insulators are viewed as semiconductors with wide band gaps.