Post-growth treatments and contact formation on CVD diamond films for electronic applications

Radiation detectors have been fabricated from undoped polycrystalline diamond films deposited using microwave chemical vapour deposition (CVD). We have investigated the influence of post-growth treatments on the detection and on the electronic properties of CVD diamond devices. The effects of various treatments, including a series of surface preparations and thermal annealing, are reported. The study was performed on devices fabricated with carbide- as well as non-carbide-forming contact materials. Devices were characterised according to the dark conductivity as well as to the alpha particle induced conductivity (CPIC technique). The study highlights the strong effects of these treatments on the detection efficiency. From the sets of results it appears that surface effects are predominant over bulk material modifications or hydrogen redistribution during annealing. This reinforces the need for optimised contact formation and post treatment, for electronic and radiation detection applications.