From a commercialization standpoint, electronic applications have been particularly elusive for diamond. Market estimates of $560 million per year by the year 2000 indicate the original enthusiasm in this area. Now such projections seem unreasonably optimistic, and even a niche commercial application in the area of electronics would be considered a success. However when taken in a broader context, this extended time frame for commercialization is not at all unusual for new technologies, and many new advances have continued to bolster the enthusiasm of diamond electronics research groups. Diamond has such an extensive list of exceptional properties that it continues to be a candidate for numerous electronic applications from heat spreaders to detectors to microvacuum tubes.
A variety of theoretical calculations established diamond's potential in the early years of CVD-diamond research. As shown in Table I, figures of merit indicated that diamond's potential far exceeded the potential of more common semiconductors such as silicon and gallium arsenide for certain applications. Typically these applications revolved around high power or high temperature. However more accurate assessments of diamond's capability after further development uncovered several issues with many electronic applications of interest: (1) n-Type doping: Although scattered reports of n-type doping have been made a high-quality, low-resistance n-type material is not available, limiting the potential applications for diamond.
(2) Deep activation of p-type carriers: At reasonable dopant levels, the activation energy for p-type carriers is approximately 0.3 eV, causing diamond to be highly resistive and sensitive to temperature variations at normal operating temperatures.