ABSTRACT
Metallization are fundamental components to all semiconductor devices and integrated circuits. The essential roles of metallization system are providing the desired electrical paths between the active regions of the semiconductor and the external circuits through the metal contacts and interconnections. The basic mechanisms of electron transport across metal-semiconductor are either by having enough thermal energy to pass over the Schottky barrier (thermionic emission) or by quantum mechanical tunnel through the barrier as a result of a sufficiently narrow barrier (field emission). The presence of parasitic resistance can significantly limit the devices performance. However, forming low resistance, thermally stable and uniform ohmic contacts to a wide bandgap semiconductor, such as GaN with a bandgap about 3.4 eV, constitutes a major obstacle to the furtherment of nitride based devices. As Schottky proposed the metal contacts barrier height is the difference between the metal work function and the electron affinity of the semiconductor.
