Single crystal diamond for electronic applications

There is significant academic and industrial interest in developing electronic devices for high-frequency, high-power and high-temperature applications. This interest has generated considerable research efforts in wide-bandgap semiconductors. Of these materials diamond has by far the most interesting and extreme properties, i.e. mechanical, optical, thermal as well as electronic. Diamond exhibits the highest breakdown field and thermal conductivity of any material and has the highest carrier mobilities of any wide-bandgap semiconductor, thereby enabling the development of electronic devices with superior performance with regards to power efficiency, power density, high-frequency properties, power loss and cooling. Nevertheless, the breakthrough of diamond-based electronics has not yet happened, largely due to the difficulty of synthesising high-quality single crystal diamond. Recent advances in growing intrinsic and boron-doped single crystal diamond intended for electronic applications have resulted in films with exceptionally low defect densities. In the intrinsic material we have reported measured room temperature drift mobilities of 4500 cm ²/V s for electrons and 3800 cm ²/V s for holes (Science 297 (2002) 1670). These mobility values were determined by using the time-of-flight technique on thick intrinsic diamond plates. For comparison, this experiment was also performed on polycrystalline and natural diamond and on silicon. Here, we describe the details of these low-field drift mobility measurements and the modeling used to describe the space-charge-limited transient current.