  Controlled placement of nanomaterials at predefined locations with nanoscale
precision remains among the most challenging problems that inhibit their
large-scale integration in the field of semiconductor process technology.
Methods based on surface functionalization have a drawback where undesired
chemical modifications can occur and deteriorate the deposited material. The
application of electric-field assisted placement techniques eliminates the
element of chemical treatment; however, it requires an incorporation of
conductive placement electrodes that limit the performance, scaling, and
density of integrated electronic devices. Here, we report a method for
electric-field assisted placement of solution-processed nanomaterials by using
large-scale graphene layers featuring nanoscale deposition sites. The
structured graphene layers are prepared via either transfer or synthesis on
standard substrates, then are removed without residue once nanomaterial
deposition is completed, yielding material assemblies with nanoscale resolution
that cover surface areas larger than 1mm2. In order to demonstrate the broad
applicability, we have assembled representative zero-, one-, and
two-dimensional semiconductors at predefined substrate locations and integrated
them into nanoelectronic devices. This graphene-based placement technique
affords nanoscale resolution at wafer scale, and could enable mass
manufacturing of nanoelectronics and optoelectronics involving a wide range of
nanomaterials prepared via solution-based approaches.
