Illumination‐dependent HF Etching of AlAs Sacrificial Layers for the Formation of “Rolled Up” Nanotubes from Strained InGaAs/GaAs Films

“Rolled‐up” nanostructures formed from lattice mismatched III‐V heterojunction films by taking advantage of a strain‐induced self‐rolling mechanism represent a useful type of building blocks for nanotechnology, with possible applications in high‐speed microelectronic and optoelectronic devices. This work investigated the effect of illumination on the hydrofluoric acid etching of AlAs sacrificial layers with systematically varied thicknesses in order to release and roll up MBE grown InGaAs/GaAs bilayers. Based on this “etch suppression effect” (ESE), we propose an illumination‐assisted technique that offers an advantage over other methods of rolling up nano‐objects on a substrate from inherently strained films because it allows control over the positioning of rolled‐up micro‐ and nanotubes independently from lithographic methods. For thicknesses of AlAs below 10 nm, we found 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 “etch suppression” area is well defined by the illumination spot, which can be used to realize well‐controlled heterogeneously etched regions on the same sample.