Selective Etching of (111)B-Oriented Al_xGa_(1-x)As-Layers for Epitaxial Lift-Off

摘要

GaAs-(111)-nanostructures exhibiting second harmonic generation are newbuilding blocks in nonlinear optics. Such structures can be fabricated throughepitaxial lift-off using selective etching of Al-containing layers and subsequenttransfer to glass substrates. Herein, the selective etching of (111)B-orientedAl_xGa_(1-x)As sacrificial layers (10–50 nm thick) with different aluminum concentrations(x = 0.5–1.0) in 10% hydrofluoric acid is investigated and compared withstandard (100)-oriented structures. The thinner the sacrificial layer and the lowerthe aluminum content, the lower the lateral etch rate. For both orientations,the lateral etch rates are in the same order of magnitude, but some quantitativedifferences exist. Furthermore, the epitaxial lift-off, the transfer, and the nanopatterningof thin (111)B-oriented GaAs membranes are demonstrated. Atomicforce microscopy and high-resolution X-ray diffraction measurements reveal thehigh structural quality of the transferred GaAs-(111) films.