Local Oxidation of Hydrogenated Diamond Surfaces for Device Fabrication

The combination of photolithography, e-beam lithography and atomic force microscopy (AFM) techniques is used for local oxidation of hydrogen terminated surfaces with a resolution down to ≈10 nm. Lithographic masks are used for treatment in oxygen plasma. In AFM the surface can be oxidized directly by application of a negative bias voltage to the tip. Using the local oxidation, transistor devices are fabricated on a (100) diamond layer, which was hydrogenated in a microwave plasma. Schottky junctions formed at aluminum contacts to hydrogenated surface are studied for comparison. Spatially resolved Kelvin probe experiments are applied to detect the potential variations in the channel or the depletion layers as a function of bias. The results are discussed focusing on current–voltage and capacitance–voltage variations.