  GaAs-(111)-nanostructures exhibiting second harmonic generation are new
building blocks in nonlinear optics. Such structures can be fabricated through
epitaxial lift-off employing selective etching of Al-containing layers and
subsequent transfer to glass substrates. In this article, the selective etching
of (111)B-oriented $Al_x Ga_{1-x}As$ sacrificial layers (10 nm to 50 nm thick)
with different aluminum concentrations (x=0.5 to 1.0) in 10 % hydrofluoric acid
is investigated and compared to standard (100)-oriented structures. The thinner
the sacrificial layer and the lower the aluminum content, the lower the lateral
etch rate. For both orientations, the lateral etch rates are in the same order
of magnitude, but some quantitative differences exist. Furthermore, the
epitaxial lift-off, the transfer, and the nano-patterning of thin
(111)B-oriented GaAs membranes is demonstrated. Atomic force microscopy and
high-resolution x-ray diffraction measurements reveal the high structural
quality of the transferred GaAs-(111) films.
