  Two-dimensional electron systems found at the interface of SrTiO3-based oxide
heterostructures often display anisotropic electric transport whose origin is
currently under debate. To characterize transport along specific
crystallographic directions, we developed a hard-mask patterning routine based
on an amorphous CeO2 template layer. The technique allows preparing
well-defined microbridges by conventional ultraviolet photolithography which,
in comparison to standard techniques such as ion- or wet-chemical etching, does
not induce any degradation of interfacial conductance. The patterning scheme is
described in details and the successful production of microbridges based on
amorphous Al2O3-SrTiO3 heterostructures is demonstrated. Significant
anisotropic transport is observed for T < 30 K which is mainly related to
impurity/defect scattering of charge carriers in these heterostructures.
