  Quality of the electrical contacts and interfaces in various
metal/semiconductor/insulator heterostructures is one of the pivotal aspects in
both applied and fundamental research areas. For instance, non-optimal contact
resistance can limit the overall efficiency of a certain developed technology
and thus considerably narrow the range or fully block its practical
application. On the other hand in fundamental research it is often the case
that the manifestation of targeted phenomenon crucially depends on the level of
contamination in the fabricated experimental samples. Here we offer a set of
recipes that are aimed at contamination-free and damage-free fabrication of the
devices, mostly developed for the two dimensional materials, but nevertheless
applicable for a wider range of the systems, where the quality of the
interfaces and/or non-invasiveness of the fabrication recipes are important.
Our recipes are based on the preparation of the flexible PMMA membranes, with
the help of which we can prepare residue-free or damage-free electrical
connections to the studied material.
