  Precision and chip contamination-free placement of two-dimensional (2D)
materials is expected to accelerate both the study of fundamental properties
and novel device functionality. Current transfer methods of 2D materials onto
an arbitrary substrate deploy wet chemistry and viscoelastic stamping. However,
these methods produce a) significant cross contamination of the substrate due
to the lack of spatial selectivity b) may not be compatible with chemically
sensitive device structures, and c) are challenged with respect to spatial
alignment. Here, we demonstrate a novel method of transferring 2D materials
resembling the functionality known from printing; utilizing a combination of a
sharp micro-stamper and viscoelastic polymer, we show precise placement of
individual 2D materials resulting in vanishing cross contamination to the
substrate. Our 2D printer-method results show an aerial cross contamination
improvement of two to three orders of magnitude relative to state-of-the-art
dry and direct transfer methods. Moreover, we find that the 2D material quality
is preserved in this transfer method. Testing this 2D material printer on
taped-out integrated Silicon photonic chips, we find that the micro-stamper
stamping transfer does not physically harm the underneath Silicon nanophotonic
structures such as waveguides or micro-ring resonators receiving the 2D
material. Such accurate and substrate-benign transfer method for 2D materials
could be industrialized for rapid device prototyping due to its high
time-reduction, accuracy, and contamination-free process.
