A Review of the Electrical Characteristics of Metal Contacts on Diamond

• Published in: Thin solid films Vol. 212; no. 1-2; pp. 19 - 24
• Main Authors: Das, K, Venkatesan, V, Miyata, K, Dreifus, D L, Glass, J T
• Format: Journal Article
• Language: English
• Published: 17.08.1991
• ISSN: 0040-6090

The formation of closely selected area ohmic and rectifying contacts on a given semiconductor surface is of fundamental interest for the fabrication of transistor type devices. However, it has been observed that the formation of good ohmic or rectifying contacts is not always easily accomplished on diamond films grown by chemical vapor deposition (CVD). Contacts established with Al or Au on CVD films exhibit highly resistive ohmic or nominally asymmetric behavior, whereas these metals can be used almost routinely to form rectifying contacts on synthetic and natural semiconducting diamond crystals. A commonly employed technique is the deposition of metals such as Ti, Ta, and Mo with a protective film of Au and a post-deposition anneal. Specific contact resistances of the order of 10 exp --5 Omega cm exp 2 have been achieved by this technique. Low-resistance contacts have also been obtained by placing metal contacts on highly doped films. A combination of boron ion-implantation, to achieve a high surface concentration, and a subsequent Ti/Au metallization has been employed for the fabrication of ohmic contacts on polycrystalline diamond films with a specific contact resistance of the order of 10 exp --6 Omega cm exp 2 .