Local oxidation of Ga[Al]As heterostructures with modulated tip-sample voltages

Abstract

Nanolithography based on local oxidation with a scanning force microscope has been performed on an undoped GaAs wafer and a Ga[Al]As heterostructure with an undoped GaAs cap layer and a shallow two-dimensional electron gas. The oxide growth and the resulting electronic properties of the patterned structures are compared for constant and modulated voltage applied to the conductive tip of the scanning force microscope. All the lithography has been performed in non-contact mode. Modulating the applied voltage enhances the aspect ratio of the oxide lines, which significantly strengthens the insulating properties of the lines on GaAs. In addition, the oxidation process is found to be more reliable and reproducible. Using this technique, a quantum point contact and a quantum wire have been defined and the electronic stability, the confinement potential and the electrical tunability are demonstrated to be similar to the oxidation with constant voltage.

Nondestructive tribochemistry-assisted nanofabrication on GaAs surface

“…The proposed method can provide new chances for the fabrication of defect-free and well-ordered nanostructures on GaAs and other chemical reactive surfaces such as Si 19 20 . Moreover, such hollow structures can also be used to define quantum structures underneath GaAs surface through charge depletion 39 .…”

On-tip sub-micrometer Hall probes for magnetic microscopy prepared by AFM lithography

“…The LAO is commonly used for the preparation of lowtemperature nano-scale structures and devices [21][22][23][24], but has not been successfully used for RT applications until now.…”

New approach to local anodic oxidation of semiconductor heterostructures

“…To sufficiently deplete the 2DEG layer of a standard heterostructure [1], it is necessary to deeply oxidize the sample to affect the remote Si-d doping layer. However, oxide lines as high as 15 nm have their base as wide as $130 nm, which considerably worsens the lateral resolution of LAO.…”

“…Fig. 1a exemplifies their heterostructure with the 2DEG layer placed 34 nm beneath the surface [1]. It is relatively deep for the formation of patterns with a lateral resolution smaller than 40 nm.…”