Metalsemicondutor

Metalsemicondutor refers to the interface formed between a metal and a semiconductor in electronic devices. At such a junction, charge transfer and band bending determine how current can flow between the two materials.

There are two principal outcomes. Schottky, or rectifying, contacts create a potential barrier at the interface that impedes current flow in one direction and allows it in the opposite direction. Ohmic contacts provide nearly linear, low-resistance transmission of carriers and are used to inject current into the semiconductor with minimal voltage drop.

Whether a contact is Schottky or Ohmic depends on the metal’s work function, the semiconductor’s electron affinity and doping level, and the presence of interfacial layers. The barrier height arises from aligning the metal’s Fermi level with the semiconductor’s bands and is sensitive to interface states that can pin the Fermi level. In n-type semiconductors, higher metal work function and thicker depletion favor a Schottky barrier, while heavy n-type doping can reduce it and promote Ohmic behavior. The reverse applies for p-type materials.

Common metals used include aluminum, titanium, nickel, platinum, and gold; semiconductors often include silicon, germanium, gallium arsenide, silicon carbide, and gallium nitride. Fabrication techniques such as annealing or alloying (for example forming silicides on silicon) are used to tailor contact resistance and thermal stability.

Applications span rectifiers, transistors, photodetectors, and sensors, where the metal–semiconductor interface controls injection, extraction, and signal integrity. Challenges include Fermi-level pinning, interfacial oxide formation, and diffusion that can degrade performance over time.