Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Rolled-Up Nanotech: Illumination-Controlled Hydrofluoric Acid Etching of AlAs Sacrificial Layers | Nanoscale Res Lett 2009 4 1463-1468 DOI s11671-009-9421-8 NANO EXPRESS Rolled-Up Nanotech Illumination-Controlled Hydrofluoric Acid Etching of AlAs Sacrificial Layers Ruxandra M. Costescu Christoph Deneke Dominic J. Thurmer Oliver G. Schmidt Received 2 June 2009 Accepted 14 August 2009 Published online 3 September 2009 to the authors 2009 Abstract 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 etch suppression 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. Keywords Rolled-up Nanotubes Nanotech Nanostructures Etching Hydrofluoric acid III-V layers Illumination-controlled Introduction and Background Rolled-up nanotech 1 2 has become a powerful technology with applications in a broad range of research fields including optofluidics 3 micromachinery 4-6 magnetofluidics 4 7 biophysics 4 8 nanomechanics 9 and waveguiding for different spectral ranges and applications 10-12 . Large arrays of periodically ordered microtubes can be fabricated by a combination of lithography and deliberate self-rolling of strained layers upon selective underetching 1 13-15 . However in some cases it might be important to stimulate tube formation in certain areas and suppress tube formation outside those areas. Precise control over the .
