Improvement in Aspect Ratio of P-GaAs Oxide Fabricated by Atomic Force Microscope (AFM)-Based Nanolithography Using Pulsed Voltage

Abstract

An atomic force microscope (AFM)-based surface nanooxidation method was used to fabricate nanoscale p-GaAs oxide. We were able to realize an increase in the aspect ratio by a factor of 2 for oxide dots using a voltage modulation technique. The aspect ratios of oxide dots reached the maximum at a frequency of about 1000 Hz. Moreover, from a duty ratio dependence of aspect ratios of oxide dots, it was considered that optimization of an anodizing time per cycle of a pulsed voltage was necessary. The oxide could be etched by water. By adjusting both oxidation and etching process conditions, a groove with a 40 nm width and 6 nm depth was successfully fabricated. From these results, it was clear that the aspect ratio of p-GaAs oxide could be improved using a pulsed voltage, and optimization of process conditions, particularly the frequency and duty ratio of a pulsed voltage, was necessary to obtain p-GaAs oxide with a high aspect ratio.