Novel nanofabrication process for InAs/AlGaSb heterostructures utilizing AFM oxidation

We demonstrate a novel nanofabrication process for InAs which is shown to be readily applicable to the fabrication of InAs based nanostructure devices, such as quantum dot or wire structures. The fabrication process is achieved by direct local oxidation using atomic force microscope (AFM). The first type of process utilizes AFM oxidation of GaSb and AlGaSb layers which form the surface layer of our InAs/AlGaSb heterostructures. The oxidized GaSb regions are selectively removed by water immersion resulting in structural modification of the surface layer that causes spatial modification of two-dimensional electron gas concentration formed in the InAs channel layer. Magnetotransport measurements revealed the successful formation of a laterally modified two-dimensional electron gas. The second type of process is based on direct oxidation of InAs layer. We found that the oxidized InAs becomes insoluble to the acetic acid based etchant enabling a selective formation of InAs islands with any shape that are drawn by AFM oxidation. We compare these AFM oxidation process and describe their feasibility as a nanoscale fabrication process.