Nanoindentation and Photoluminescence Studies on Hydrogenated Boron Carbon Nitride Thin Films

Abstract

Compounds in boron-carbon-nitrogen ternary triangle such as diamond (C), cubic boron nitride (c-BN), and boron carbide (B4C) have gained attention due to their covalent bonding, short bond lengths, low atomic mass[1]. These materials exhibit low dielectric values along with excellent mechanical and thermal strength. Boron carbon nitride (BCN) compounds are known to combine unique properties of boron carbide and boron nitride, with the properties being tunable with varying elemental composition and structure. These outstanding properties have made BCN attractive and finds multi-functional applications in anti-wear and protective coatings, supercapacitors, UV detectors, nanobiotechnology and nanomedicine[2]. While addition of small amounts of hydrogen has been proven beneficial for electrical and optical properties in BCN films, the influence of hydrogen on mechanical properties have not yet been reported.In this study, BCN thin films are deposited using RF magnetron sputtering with varying hydrogen/nitrogen gas flows and substrate deposition temperature. Dual target sputtering from B4C and BN targets is performed to deposit BCN thin films. The chemical composition, hardness, Young’s modulus and photoluminescence properties of BCN films are measured as a function of gas flow and substrate temperatures. Hardness of the BCN films range between 6 – 22 GPa and Young’s modulus between 125 – 140 GPa. Photoluminescence (PL) studies are performed at room temperature and 77K. PL peak shifts are observed in BCN films deposited at different substrate temperatures.