SGER: Near-Field-Controlled Nanoscale Coating of Functional Thin Films for Nanodevices

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Objective: Various micro/nanodevices have been designed and fabricated to perform complex functions in mechanics, electronics and photonics. Nanoscale coating of functional thin films is one of the major processing steps in many important device applications. There is tremendous impetus to develop a nanoscale controllable surface coating technique and establish fundamental understandings of nanoscale surface processes for the purpose to improve micro/nano-device performance and reliability. The overarching goal of the proposed research is to develop a novel near-field photochemical process for self-controlled deposition of functional thin films. The project objectives are to 1) simulate nanoscale local light enhancement by nanodevices; 2) detect near-field-enhanced photochemistry; 3) deposit diamond-like carbon (DLC) films on micro/naonelectromechanical system (MEMS/NEMS) devices using laser-assisted chemical vapor deposition (CVD); and 4) characterize tribological performance of DLC-coated MEMS/NEMS.Innovative method: In the proposed research, a visible and/or UV laser will be used to irradiate nanostructures such as nanotips, MEMS/NEMS devices in liquid or gaseous precursors. Due to the near-field effects, highly locally confined and enhanced electromagnetic (EM) waves in the vicinity of sharp-tips/edges can be used for optical decomposition of liquid or gas precursors for a self-controlled deposition of thin films. The process combines the advantages of conventional laser chemical deposition and optical near-field effects, so that highly spatially-localized deposition can be achieved. Our recent work experimentally proved that there are near-field effects in the pulsed excimer laser deposition of DLC films on W nanotips in a benzene solution.A tip-sharpness-dependent coating of DLC on W nanotips and a phase gradient along the tip apexes were observed. This inspires us to propose a near-field-based self-deposition process which is well controlled at nanoscales.Intellectual Merit: The proposed research is a new field involving near-field-optics. The proposed research is to utilize optical near-field as local energy sources for nanoscale chemical reactions. The significance is two-fold: First, it is a controllable surface process which extends surface coating to 3-D device structures. Fundamental understanding of nanoscale material deposition by highly spatially-confined EM wave is of major scientific interest. Second, it is a technique directly addressing the need for coatings on sharp tips and edges of nanodevices, especially as self-lubricating and protective coatings for extensive wear applications at nanometric levels.Broader Impacts: This research will benefit the society by revolutionizing the efficiency, cost, and positioning accuracy of coating functional thin films on 3-D device structures which have wide applications such as semiconductor, photonics, electronics, and consumer products, having a profound impact on all societal levels. Research outputs will be disseminated via a website and through different conferences. One graduate student from an underrepresented minority and two undergraduates will work on the proposed project. An animation kit showing the applications of MEMS/NEMS and basic ideas on the thin film deposition at the nanoscale will be developed and distributed to K-12 teachers and students in annual public seminars.