  Deterministic transfer of two-dimensional crystals constitutes a crucial step
towards the fabrication of heterostructures based on artificial stacking of
two-dimensional materials. Moreover, control on the positioning of
two-dimensional crystals facilitates their integration in complex devices,
which enables the exploration of novel applications and the discovery of new
phenomena in these materials. Up to date, deterministic transfer methods rely
on the use of sacrificial polymer layers and wet chemistry to some extent.
Here, we develop an all-dry transfer method that relies on viscoelastic stamps
and does not employ any wet chemistry step. This is found very advantageous to
freely suspend these materials as there are no capillary forces involved in the
process. Moreover, the whole fabrication process is quick, efficient, clean,
and it can be performed with high yield.
