  We report on the post-growth shaping of free-standing 2D InAs nanofins that
are grown by selective-area epitaxy and mechanically transferred to a separate
substrate for device fabrication. We use a citric acid based wet etch that
enables complex shapes, e.g., van der Pauw cloverleaf structures, with
patterning resolution down to 150 nm as well as partial thinning of the nanofin
to improve the gate response. We exploit the high sensitivity of the cloverleaf
structures to transport anisotropy to address the fundamental question of
whether there is a measurable transport anisotropy arising from
wurtzite/zincblende polytypism in 2D InAs nanostructures. We demonstrate a
mobility anisotropy of order 2-4 at room temperature arising from polytypic
stacking faults in our nanofins. Our work highlights a key materials
consideration for devices featuring self-assembled 2D III-V nanostructures
using advanced epitaxy methods.
