Recent Developments in Functional Thin Films

Abstract

Thin film technology is a significant focus of academic, governmental, and industrial research efforts. The economic impact of thin film use is significant and is growing at an impressive rate. BCC Research assigned the thin film global market a value of $9.3 billion in 2011; it is anticipated to reach a value of $14.9 billion by 2016. 1 Drivers of thin film research at this time include lowering the processing cost and environmental burden associated with thin film processing. 2 In addition, efforts are underway to develop thin films on flexible substrates for use in medical prostheses and in energy harvesting devices. Functional thin films have other potential biomedical applications, including use in drug delivery. 3 A search using Thomson Reuters’s Web of Knowledge indicates that the number of published items involving functional thin films has steadily increased each year since 1994; more than 1150 papers were published on this topic and nearly 30,000 citations involved this topic in 2012. 4 In this issue of JOM, the development of thin films for biomedical, corrosion resistance, electronic, optical, radiation detection, thermal barrier, and tribological applications is described. In ‘‘Improved Mobility and Transmittance of Room-Temperature Deposited a-IGZO Films with Low-Temperature Post-Fabrication Anneals,’’ T.L. Alford et al. demonstrate radio frequency (RF) sputtering of amorphous indium gallium zinc oxide onto flexible poly ethylene naphthalate substrates. Annealing the film at low temperatures in an oxygen atmosphere and in vacuum is shown to modify the optical and electrical properties of the thin films. In ‘‘Inkjet Printing of Amphotericin B onto Biodegradable Microneedles using Piezoelectric Inkjet Printing,’’ R.D. Boehm et al. demonstrate modification of the surfaces of Gantrez (ISP Investments, Inc., Wilmington, DE) 169 BF microneedles with amphotericin B using piezoelectric inkjet printing. A radial diffusion assay is used to demonstrate the activity of these drug-loaded microneedles against the yeast Candida parapsilosis. In ‘‘Effect of LowTemperature Microwave Processing and Copper Content on the Properties of Ag-Cu Thin Film Alloys,’’ S. Das and T.L. Alford examine the use of microwave annealing for enhancing the structural and electrical properties of silver-copper thin films. Their work indicates that copper oxide encapsulation layers are formed by microwave annealing. In ‘‘Reflectance Spectroscopy of Functional Ag-Cu Thin Films: Correlation of Reflectivity with Cu Content,’’ S. Das and T.L. Alford evaluate the use of magnetron sputtering to co-sputter pure silver and copper targets. The electrical mobility and optical reflectivity properties of silver-copper thin films on silicon substrates are evaluated. In ‘‘Thermo-mechanical