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

A diffusion and reaction related model of the epitaxial lift-off process

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Strain-accelerated HF etching of AlAs for epitaxial lift-off

Contains fulltext : 60629.pdf (publisher's version ) (Closed access)Epitaxial lift-off (ELO) is a process which allows for the separation of a single crystalline III/V thin film or device from the substrate it was deposited on. This process is based on the selective etching of an intermediate AlAs release layer in an aqueous HF solution. The lateral etch rate of the AlAs release layer through a narrow crevice in the weight-induced epitaxial lift-off (WI-ELO) process is much larger than observed for unobstructed planar AlAs layers. It is possible that this increase in etch rate is caused by the tensile strain induced upon the AlAs layer in the WI-ELO setup. In order to verify this assumption, planar AlAs layers, subjected to a controlled curvature, were etched in HF solutions and their etch duration was measured. The applied curvature reduced the already present compressive strain due to lattice mismatch. For large applied bending radii no change in etch rate was observed, because the induced bending is smaller than the already present bending due to the lattice mismatch. Further bending induces a total compressive strain from -0.126% to -0.11%, resulting in an etch rate variation from 0.054 up to 0.066 mm h(-1). Measurements on AlAs layers experiencing a tensile strain of +0.286% showed much higher etch rates of 0.134 mm h(-1). The present results obtained on etching experiments in the lateral plane are extrapolated to the perpendicular direction so that a combination with the data from previous work becomes feasible. This results in a better microscopic picture of the etch front in the WI-ELO process. It is found that the force exerted by the weight can be projected on an area, limited by the sample width and a depth of approximately 6 mum

The influence of InxGa1 xAs and GaAs1 yPy layers surrounding the AlAs release layer in the epitaxial lift-off

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Electrochemical-chemical deposition and etching - Study of wet chemical of AlxGa1-xInP2 films using hydrochloric Acid

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Photon confinement in high-efficiency, thin-film III-V solar cells obtained by epitaxial lift-off

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Quantitative analysis of variant III CuAu-I-type ordering of AlxGa1-xAs on (110), (111)A and (001) GaAs substrates using X-ray diffraction

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Synchrotron radiation study of order in AlxGa1-xAs

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SPECTRUM AND BANDGAP OPTIMIZED ANTIREFLECTION COATING BY NUMERICAL SIMULATION

Item does not contain fulltext20th European Photovoltaic Solar Energy Conference, 6 – 10 June 2005, Barcelona, Spai