A review of the electrical characteristics of metal contacts on diamond
The formation of closely spaced 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 aluminum or gold 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. Considerable effort has been directed towards producing low resistivity ohmic contacts on natural semiconducting crystals. A commonly employed technique is the deposition of metals such as titanium, tantalum and molybdenum with a protective film of gold and a post-deposition anneal. Specific contact resistances of the order of 10-5ohmcm2 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 10-6ohmcm2. © 1992.
Das, K; Venkatesan, V; Miyata, K; Dreifus, DL; Glass, JT
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