Fabrication of diamond single-hole transistors using AFM anodization process

By the field-assisted local anodization technique using an atomic force microscope (AFM), a single-hole transistor has been fabricated on an undoped hydrogen-terminated diamond surface where p-type conduction occurs on the subsurface region. A dual side-gated FET structure has been applied to modulate the island potential in the single-hole transistor. The island size is 230 nm×230 nm, and the width of the barrier is approximately 100 nm. Measurements of the current-gate voltage characteristic at a temperature of 4.6 K show significant non-linearities including a current oscillation suggestive of single-hole transistor behavior. The oscillation that is significantly affected by the application of the side gate potential is explained by the shrinkage of the conductive island with the expansion of the depletion region.