Sarcouncil Journal of Applied Sciences Aims & Scope

Abstract: Thin films are engineered layers with thicknesses from less than nanometers to micrometer scale, their performance is influenced by surface and interfaces, defects and grain boundaries, residual stresses, confinement effects and material properties. This article introduces the way the performance of thin film is affected and a characterization overview is given through the application of the process-structure-property relationships in combination with the major fabrication technologies. Various PVD and CVD techniques like thin film sputtering, thermal evaporation, EB-evaporation, pulsed laser deposition PLD, CVD, PECVD, ALD as well as sol-gel, spin-coating, doctor-blade, spray-pyrolysis and chemical bath are discussed. Material's phases, size and orientation of grains, roughness, porosity, composition and quality of the interface between phases and between films are influenced by factors like surface condition, substrate preparation, nucleation, adatom migration and diffusion, vacuum condition or reagent composition, deposition rate, substrate temperature, plasma factors (e.g., electron density, plasma potential etc.) and heat treatment. Both approaches complement in determination of the desired structure and properties. XRD, XRR give structural properties and thickness. SEM, TEM and AFM explain structure and morphology of thin film. Composition is identified by EDS, XPS and bonding state by FTIR, Raman spectroscopy and so on. Optical properties (ellipsometry, UV-vis spectroscopy, photoluminescence) and electrical properties (4 points probe, Hall effect etc.) are found. Currently research focuses on low-temperature fabrication, plasma assistance, fabricating at an atomic scale, on line monitoring and optimization by the use of machine learning to enable scalable manufacturing with good yields, saving materials. Major remaining issues are reliability and scalability problems, precise control of interface, estimation of errors due to measurement inaccuracy and residual stress. Sustainable manufacture approaches are in investigation.