Surface patterning and functionalisation by local anodic oxidation on CVD diamond

Local Anodic Oxidation (LAO) of hydrogenated CVD diamond surfaces has been carefully investigated as a function of the scanning speed, relative humidity and bias voltage. As examples, a perfect control of the width of the oxidised lines between 80 and 1 10 nm has been demonstrated for scanning speeds between 20 and 1 10 nm/s, at 60% relative humidity and between 45 and 90 nm by switching the humidity from 40 to 60%. The oxidation process is indicated by the decay of the current during LAO process, which is concluded in about 10 s. The interpretation of the results, which in literature oscillates between grooves digging and creation of oxidised bumps, is still quite difficult, since it depends on the AFM mode ('contact' or 'non contact'), which has been used for LAO. A true oxidation process is more likely to occur, as indicated by our results and it is in agreement with the presence of oxygen in surface analysis data.