The effects of plasma post-treatment on the photoresponsivity of CVD diamond UV photodetectors

In this paper, we report the influence of room temperature post-treatment using an oxygen and carbon tetrafluoride plasma on the photoresponsivity of chemical vapour deposited (CVD) polycrystalline diamond UV photodetectors. X-ray diffraction (XRD) measurements show that the plasma-treatment preferentially passivates the defects at the (220) and (311) facets of diamond film. Photoluminescence (PL) and Raman measurements carried out on these diamond surfaces indicate that the plasma can effectively etch the sp2-bonded carbon impurities and passivate the silicon-vacancy defects. Plasma post-treatment employed on devices resulted in more than two orders of magnitude increase in the photoresponsivity discrimination between the UV (∼225 nm) and visible light (∼700 nm) regions.