Fermi Level Pinning in GaAsSb Schottky Barriers
Project Description
The type - II InP-GaAsSb heterojunction builds the basis for high speed transistors and optoelectronics. One of the key aspects in creating faster and more efficient devices is the metallic contact to the ternary material. However: The fundamental physical mechanisms determining the barrier to electron and hole flow at the metal-semiconductor interface in a practical Schottky diode are not well understood. The formation of a practical Schottky diode consists of depositing a metal film onto a real semiconductor surface, a surface which is not ideal but contaminated by a few monolayers of adsorbed foreign atoms or covered by a thin layer of native oxide. In the case of GaAs and some III-V semiconductors, the Fermi level Esf at the interface is found to be pinned as a result of surface states and thus almost independent of the metal work function.