Diamond is a unique material that often exhibits extreme properties compared to other materials. Discovered about 30 years ago, the use of hydrogen in plasma-enhanced chemical vapor deposition (CVD) has enabled the growth and coating of diamond in film form on various substrate materials. CVD diamond research has been actively continued subsequently to develop new understanding and approaches for the growth and processing of this fascinating material. Currently, the study and development of diamond films has enabled a wide range of applications based on the combination of unique and extreme properties of diamond and the variety of film properties obtainable through tuning the microstructure, morphology, impurities, and surfaces. This issue of MRS Bulletin introduces the latest research, recent applications, and the challenges ahead for CVD diamond films.

I was invited to write this article after I gave a talk about setting up a preoperative assessment clinic. If you're facing the daunting task of providing a new service in your primary or secondary care job I hope that you'll find something useful here. Before I begin I'll repeat the confession that I made when I gave my talk. I am not an expert. In fact I have had little experience setting up new clinics. What I have done here is distil the experience of colleagues from around the country with whom I have had the pleasure of talking. These are their words.

Nanocrystalline diamond thin films of sub-micron thickness have been covalently modified with DNA oligonucleotides. Quantitative studies of hybridization of surface-bound oligonucleotides with fluorescently tagged complementary and non-complementary oligonucleotides were performed. The results show no detectable nonspecific adsorption, with extremely good selectivity between matched and mismatched sequences. Impedance spectroscopy measurements were made of DNA-modified boron-doped nanocrystalline diamond films. The results show that exposure to non-complementary sequences induce only small changes in impedance, while complementary DNA sequences produce a pronounced decrease in impedance. The combination of high stability, selectivity, and the ability to directly detect DNA hybridization via electrical means suggest that diamond may be an ideal substrate for continuously-monitoring biological sensors.

A density-functional based tight binding method was used to study elementary steps in the growth of ultrananocrystalline (UNCD) diamond. It was shown previously that C2 dimers are the dominant growth species in hydrogen-poor argon plasmas. Recent experimental evidence shows that nitrogen addition to the plasma profoundly changes the morphology of the UNCD film. CN species are believed to play a major role. Reactions of C2 and CN molecules with reconstructed diamond (100) surfaces were studied. A single CN prefers an end-on attachment to a surface atom on the unhydrided (100) surface with its C end down. It is shown how further C2 addition to the surface leads to CN-mediated diamond growth and how the CN species remain on top of the growing diamond layer.