Single crystal microwave plasma deposited CVD diamond
Daniel J. Twitchen, Geoffrey A. Scarsbrook, Andrew J. Whitehead, Chris Wort & Steve. E. Coe
Element Six Ltd, King's Ride Park, Ascot, Berkshire SL5 8BP, UK.
Division for Electricity Research, Box 539, S-751 21 Uppsala University, Sweden.
The desire for electronic devices with higher power throughput, wider frequency bandwidth and higher operational temperatures is driving research and development of new semiconductors. One such area is wide band gap materials. Diamond is extreme in this group of materials that includes SiC, ZnO and GaN, having a direct band gap of 7.5 eV, an indirect gap of 5.5 eV and a room temperature thermal conductivity in excess of 2000 Wm-1K-1. Diamond electronic devices, such as power diodes and high-frequency field effect transistors, are expected to deliver outstanding performance due to the material's excellent intrinsic properties such as high carrier mobilities and high breakdown field. However, the development of diamond electronics has been hampered by several problems including a lack of shallow dopants, heteroepitaxy as a route to large area single crystal growth, low crystal quality and poor consistency of synthetic material.
We will report recent results on the fabrication and characterization of device quality single crystal CVD diamond.  These results show, not only that material can be fabricated with performance that matches the very best natural diamond, but also that key properties such as the mobility and lifetime of the carriers, far exceed expectations. It has been lack of material quality that has limited diamond's progress in the past, making it a minority player against SiC and GaN. However, the figures of merit now demonstrated for diamond are so extreme that the material should be re-examined as an ideal material for the most demanding power electronics and switching applications.
 J. Isberg et al., Science, 6 Sept, 297 (2002) p1670.