The Micromachined Diamond Device Initiative (MIDDI) led by researchers at Element Six Ltd in collaboration with the Institute of Photonics (IoP) at the University of Strathclyde has been completed successfully. The aim of MIDDI, which was part-funded by the UK Department of Trade and Industry, was to develop world-leading technologies for diamond microelectronic device manufacturing to give European companies a competitive edge over Japan and the US.

MIDDI's main focus was on the development of a 'tool-kit' of advanced micro- and nano-scale manufacturing technologies that could be used for the development of next generation high-frequency and high-power electronic devices based on synthetic single crystal diamond. Element Six is already a world leader in manufacturing electronic grade synthetic diamond using chemical vapour deposition. MIDDI further advances this leadership.

The role of the IoP has been to provide the expertise in plasma etching technology, which is used to define the precise surface features required in device fabrications. Established in 1995, the Institute has become a centre of expertise in etching materials that have traditionally been difficult to process. Its research interests include semiconductor materials and devices, practical, all solid state lasers, micro-LED arrays and a wide range of applications particularly in biophotonics.

Prof Martin Dawson, Associate Director of the IoP commented, "The MIDDI project has been a showcase example of how UK universities and industry can collaborate on successful technological development. Element Six framed the project challenge and provided advanced diamond structures with controlled doping characteristics; the University met the challenge by developing an innovative dry etching approach that is being jointly patented. This opens the way to truly manufacturable diamond electronics, but also has wider implications for a host of new technologies including diamond photonics where, with support from Element Six, the University of Strathclyde now has a significant presence."

The project has made significant achievements in three areas that will help Element Six support the development of active electronic devices fabricated in diamond. Firstly, it has led to improved technology for synthesis and processing used in the production of substrates and epitaxial layers with atomic-scale low roughness surfaces. The ability to make nano-scale layers of diamond with high precision depends on a number of complex processing and synthesis steps. For a high frequency active electronic device, some of the individual layers are required to have thicknesses of a few nanometres. In addition, these layers need to be atomically smooth, and have extremely sharp doping profiles.

Secondly, Element Six is now able to deposit thin layers of boron-doped diamond at the nano-scale. Proposed device concepts for active switching based on diamond such as the delta MESFET use such thin layers sandwiched between two undoped intrinsic diamond layers to support transistor action. Finally, MIDDI has led to a robust and reproducible dry etching technology suitable for transistor device fabrication.

These successful outcomes have already underpinned the formation of a new subsidiary by Element Six, Diamond Microwave Devices Ltd, which is aiming to develop the world's first commercial high frequency, high power diamond transistors. The technology developed under MIDDI could also be of benefit to other areas of diamond technology used in advanced applications such as radiation detectors and micro-optic devices.