Nanoscale modification of the hydrogen-terminated diamond surface using atomic force microscope

Local insulation on the hydrogen-terminated homoepitaxial diamond (001) surface was performed using an atomic force microscope (AFM). The mechanism is analogous to electrochemical anodic oxidation in which the sample acts as an anode while the AFM tip acts as a cathode and the water layer from the atmosphere between the tip and the sample surface works as the electrolyte. The current measured during insulation indicates the anodization characteristics of the process. The surface modification has been found to be strongly dependent on the electric field between the sample and the tip. We also demonstrate the modification with the alternating current (AC) voltage bias. This method prevents buildup of space charge during modification and leads to the increase of the modified line width compared with the static voltage bias. Under proper conditions, such as suitable writing speed and bias voltage, the minimum line width reaches 35 nm in the case of AC bias.