Optimization of in-vacuo template-stripped Pt surfaces via UHV STM

Abstract

A recently demonstrated [1] in-vacuo templatestripping process is applied to the study of platinum films stripped from ultra-flat silicon-oxide surfaces. Templatestripped (TS) Pt surfaces, prepared with a range of postdeposition annealing times prior to being stripped from the templating surface in an ultra-high vacuum (UHV) environment, are examined by UHV scanning tunneling microscopy (STM). These studies reveal that without post-deposition annealing, TS Pt surfaces are largely made up of poorly-ordered, granular nanostructures undesirable for many applications. The post-deposition annealing treatments explored in the study result in the emergence and continuous growth of large smooth crystallites. Issues with crystallite orientation relative to the TS surface and artefacts arising as a result of the epoxy used in the template-stripping process are presented and discussed in relation to optimizing the template-stripping procedure for specific applications such as self-assembled monolayer (SAM) formation for molecular electronics.

Formation and Elimination of Surface Nanodefects on Ultraflat Metal Surfaces Produced by Template Stripping

“…This is based on the interfacial phenomena of SAMs such as wetting and the wettability of surfaces, sensing and sensors, tribology, organic electronics, tuning adhesion, corrosion resistance, nanofabrication, and templates for the nucleation and growth of crystals. − In many of these applications and devices, the surface properties of the SAMs themselves constitute a key issue; therefore, there is a need for the largest possible number of defect-free SAM domains. In the case of thiolated SAMs on coinage metals, two main approaches have been employed to achieve ultraflat and large defect-free domains: (i) using high-quality polished single-crystalline substrates and (ii) using ultraflat polycrystalline substrates via the template stripping (TS) technique in which the average root-mean-squared (rms) roughness is on the order of <1 nm. − The first approach is very costly and useful only for basic research studies, and the second approach is relatively cheap and has been widely used in the last two decades, having been improved somewhat over the years. , A few examples of the broader use of TS surfaces are plasmonics, bionanosensors, the measurement of molecular friction, molecular electronics, and molecular optoelectronics . Nevertheless, the great drawback of the TS method is the small polycrystalline grains obtained via physical vapor deposition (PVD).…”

Scanning Tunneling Microscopy of Template-Stripped Au Surfaces and Highly Ordered Self-Assembled Monolayers

“…[7][8][9][10][11] Solutiondeposited alkanethiol SAMs on the coinage metals Au, Ag, Pt, and Pd are among the best studied monolayer systems; it is well established that these molecular monolayers of 1-3 nm thickness are readily disordered by the 2-5 nm peak-to-valley roughness and grain boundaries typical of the metal surfaces. Ultraflat template-stripped (TS) metal surfaces [12][13][14][15] have been shown to serve as a substrate for ordered molecular structures of solution-deposited SAMs. [16][17][18][19] Until now, however, no study has validated the TS surface preparation through in situ ultrahigh vacuum (UHV) investigations of the TS surface and the subsequently assembled molecular monolayer.…”

“…Although self-assembled monolayers (SAMs) have been shown to produce locally well-ordered molecular structures via both solution phase and vapor phase deposition, in almost all cases, the longer range structural order in the SAM is limited by the surface roughness of the underlying substrate. – Solution-deposited alkanethiol SAMs on the coinage metals Au, Ag, Pt, and Pd are among the best studied monolayer systems; it is well established that these molecular monolayers of 1−3 nm thickness are readily disordered by the 2−5 nm peak-to-valley roughness and grain boundaries typical of the metal surfaces. Ultraflat template-stripped (TS) metal surfaces – have been shown to serve as a substrate for ordered molecular structures of solution-deposited SAMs. – Until now, however, no study has validated the TS surface preparation through in situ ultrahigh vacuum (UHV) investigations of the TS surface and the subsequently assembled molecular monolayer. In this paper, we report such a UHV scanning tunneling microscopy (STM) investigation of TS Au surfaces stripped in UHV, and octanethiol SAMs vapor-deposited in situ onto those surfaces.…”

“…The thin film layer structure and fabrication process for the TS Au is described in Figure . This process has been improved from our initial UHV study of TS metals , to better control surface grain structure. In this improved process, Au thin films with a thickness of 500 nm were electron-beam deposited at 300 K onto a Si(001) template that had a 5 nm dry, thermally grown oxide layer.…”

Formation of a Flat Conductive Polymer Film Using Template-Stripped Gold (TSG) Surface and Surface-Graft Polymerization for Scanning Multiprobe Data Storage

“…In recent years, ultraflat metal surfaces have been fabricated by a template-strip method [20][21][22][23][24][25][26]. In particular, template-stripped gold (TSG) surfaces have been of use to form and study highly ordered SAM on large area.…”