Vanadium dioxide (VO2) is widely employed
in developing
tunable optoelectronic devices due to its significant changes in optical
and electric properties upon phase transition. To fabricate the VO2-based functional devices down to the micro/nanoscale, a high-resolution
processing technique is in demand. Scanning probe lithography (SPL)
on the basis of a tip-induced electric field provides a promising
approach for prototyping. Here, we demonstrated a precise VO2 etching strategy by direct writing on a VO2 film with
a negative tip bias and subsequent sonication removal of the written
area. The effects of bias voltage, sonication, and thermal treatment
as well as the mechanical difference between the tip-modulated area
and the pristine VO2 film were investigated systematically.
The results show that VO2 can be etched layer by layer
via alternately repeating tip modulation and sonication, and arbitrary
patterns can be written. Based on this route, we designed a kind of
metasurface by arranging VO2–gold nanoblocks with
different sizes and heights for spectrally selective tunable reflectivity
in near- and mid-infrared. This electric-field SPL method demonstrates
the prominent advantages of high resolution down to several tens of
nanometers, quasi-3D patterning, and resist-free maskless direct writing,
which should be applicable for prototyping other micro/nanodevices.