Fundamentals and practice of metal contacts to wide band gap semiconductor devices

• Published in: Crystal research and technology (1979) 2012-03, Vol.47 (3), p.261-272
• Main Authors: Borysiewicz, M. A., Kamińska, E., Myśliwiec, M., Wzorek, M., Kuchuk, A., Barcz, A., Dynowska, E., di Forte-Poisson, M.-A., Giesen, C., Piotrowska, A.
• Format: Article
• Language: English
• Subjects: diffusion barriers; GaN; ohmic contacts; SiC; wide bandgap semiconductors
• ISSN: 0232-1300; 1521-4079
• DOI: 10.1002/crat.201100490

Presented are the theoretical and experimental fundamentals of the fabrication of ohmic contacts to n‐ and p‐type wide band gap semiconductors such as SiC and GaN. In particular, the Ni‐Si/n‐SiC, Al‐Ti/p‐SiC, Ti‐Al/n‐GaN and Ni‐Au/p‐GaN systems are discussed with the focus on the thermally activated chemical reactions taking place at the metal‐semiconductor interface, that lead to the appearance of ohmic behaviour in the contact. Examples of reactions at very intimate interfaces are shown, which are irresolvable using even such sophisticated characterisation methods as high‐resolution transmission electron microscopy and can only be explained using modelling. The issue of thermal stability of the contacts is discussed and the introduction of specifically designed diffusion barriers (eg. Ta‐Si‐N) into the contact metallisation stack is presented as a solution improving drastically the thermal stability of the contacts without degrading their electrical properties. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)