The desire to exploit the extreme properties which differentiate diamond from other, more mature wide bandgap technologies has recently been given further impetus by the development of high quality single crystal CVD diamond material .
To realise the significant potential of diamond devices over existing device technology depends on completing a number of key objectives, in particular providing:
(a). access in volume to high quality, ultra-high purity, single crystal material,
(b). the capability to provide carriers by doping the material in a controlled manner,
(c). the ability to process thin layers and structures.
Providing access to bulk single crystal diamond (albeit not electronic grade material) has already been largely achieved and plates are commercially available for cutting applications . Routes to providing suitable charge carriers are being widely investigated. Although intrinsic diamond can have exceptional electronic properties , in reports of both p-type and n-type diamond [3,4] the dopants are very deep (0.37 eV and 0.6 eV for boron and phosphorous respectively), which limits the realisation of conventional electronic devices operating at ambient temperatures.
A series of novel devices undergone preliminary experimental evaluation. Devices made up of boron and intrinsic layers, where the boron concentration exceeds the limit of metallic conduction (>1×1020 cm−3), offer carrier diffusion at room temperature from the highly doped regions with low mobility, into adjacent regions of intrinsic material with high carrier mobility . To provide the required device performance, the interface between the doped and intrinsic layers needs to be defect free and to change doping levels by several orders of magnitude in a few atomic layers.
Although progress over the last few years has been rapid, there remain substantial technical challenges ahead for the realisation of large scale diamond active electronics. This paper will identify and review progress against these key issues.