Metal Contacts in Semiconductors.
Final technical rept. Sep 80-Sep 83,
NEW UNIV OF ULSTER COLERAINE (NORTHERN IRELAND)
Pagination or Media Count:
The application of modern surface science experimental techniques to probe free semiconductor surfaces and their interfaces with gases and meals has enabled a much greater understanding of the role that imperfections, defects etc. play in the formation of Schottky barriers and related devices. In section 1 of this report we detail the interactions between various metals and vacuum cleaved and air cleaved 110 surfaces of CdTe. For metal vacuum cleaved CdTe interfaces we show that the interfaces formed are very non abrupt with interface widths in some cases exceeding twenty five angstroms. Also, provided one eliminates the systems where cadmium outdiffusion into high work function metals occurs then good agreement between the linear interface model in the Schottky limit and the data occurs. Where cadmium outdiffusion into high work function metals does occur it is postulated that Fermi level pinning in the band gap occurs due to the formation of doubly charged cadmium vacancies. The presence of an interfacial layer, due to oxidation or due to deposition of very thin 2 Angstroms aluminum layers, between the vacuum cleaved CdTe surface and the metal overlayer drastically effects the Schottky barrier height. Oxidation of the surface prior to metal deposition always leads to an increase in Schottky barrier height.
- Atomic and Molecular Physics and Spectroscopy
- Solid State Physics