Thin Film Amorphous Electrolytes: Structure and Composition by Experimental and Simulated Infrared Spectra

Ionic conducting glasses in thin film forms are promising candidates for applications in microelectronics devices such as microbatteries and microsupercapacitors. In recent years, it was shown that physicochemical properties of thin films may differ substantially from those of the target bulk materials. Thus, it remains a challenge in science and thin film technology to control the properties of thin films in terms of chemical composition and conditions of manufacturing. This work presents a structural investigation of lithium−borate thin film electrolytes prepared by rf sputtering of Li−diborate targets. Chemically stable thin films ca. 1 μm thick were deposited on Si and gold-covered Si substrates under argon and their infrared spectra were measured in a broad spectral range (30−5000 cm-1). The spectra of thin films were modeled on the basis of rigorous expressions for reflectance and transmittance of the film/substrate bilayer system. The experimental results for thin films were compared with those sim...