Template Stripping of Diverse and Heterogeneous Surfaces for Scalable Molecular Electronics

Reliable molecular junctions require high-quality self-assembled molecular monolayers. To form such monolayers, clean, ultra-smooth (&lt; 1 nm root-mean-square roughness) growth surfaces are required. One approach to such surfaces is template stripping, where the material of interest is deposited on a template, such as a silicon wafer, then delaminated from the underlying substrate, revealing a clean, ultra-smooth surface suitable for molecular assembly. Conventionally, this template stripping approach has been limited to large-area surfaces of metals such as Au, Ag, Pd and Pt, which naturally have low adhesion to the underlying silicon surface, allowing for delamination. Though suitable for fundamental studies, these large-area surfaces of low-adhesion noble metals have limited prospects for integration into molecular devices and systems.<br/><br/>Here, we demonstrate template stripping of diverse materials (Au, Pt, Al, SiO₂, Al₂O₃) including and beyond those achievable through conventional template stripping approaches. We overcome the requirement for a low-adhesion material by functionalizing the underlying silicon substrate with molecular release layers that enable reliable stripping regardless of material adhesion, while maintaining the surfaces ultrasmooth (&lt; 1 nm). This expands the use of template stripped surfaces to the assembly of diverse molecular monolayers beyond those readily compatible with assembly on conventional, noble metal surfaces. This approach further opens the possibility of integrating molecules with materials, beyond noble metals, that display functionalities, such as spintronic or semiconducting, critical for the emerging molecular devices. We further demonstrate lithographic patterning of template stripped surfaces to realize ultra-flat, ultra-smooth surfaces composed of multiple materials. These planarized heterogenous surfaces allow for orthogonal assembly chemistries to be run on the same substrate, opening possibilities for fabrication of more complicated molecular device architectures. Because our template stripping approach mirrors conventional wafer bonding, we discuss its prospects for scalable fabrication of substrates suitable for molecular electronic devices on an industry-compatible toolset.