Rolled-Up Nanotech: Illumination-Controlled Hydrofluoric Acid Etching of AlAs Sacrificial Layers

<p>Abstract</p> <p>The effect of illumination on the hydrofluoric acid etching of AlAs sacrificial layers with systematically varied thicknesses in order to release and roll up InGaAs/GaAs bilayers was studied. For thicknesses of AlAs below 10 nm, there were two etching regimes for the area under illumination: one at low illumination intensities, in which the etching and releasing proceeds as expected and one at higher intensities in which the etching and any releasing are completely suppressed. The &#8220;etch suppression&#8221; area is well defined by the illumination spot, a feature that can be used to create heterogeneously etched regions with a high degree of control, shown here on patterned samples. Together with the studied self-limitation effect, the technique offers a way to determine the position of rolled-up micro- and nanotubes independently from the predefined lithographic pattern.</p

Modulation-doped SixGe1-x/Si shells electrically isolated from conductive substrates

Results on the formation of tubes and helices with micron and submicron radii of curvature formed from modulation-doped SixGe1-x/Si heterostructures are presented. A novel technology allowing electrical isolation of 3D micro- and nanoshells from conductive substrates has been developed. The possibility of controlling the local curvature radius of submicron shells by means of electron beam irradiation is demonstrated, presenting a novel method of modifying electronic and transport properties of formed shells