Sensitive determination of mechanical and thermal properties of MoS2 multilayers using microcantilevers

Abstract

Understanding the mechanical and thermal properties of MoS₂ multilayers is of importance for applications ranging from nano-mechanical structures to high-performance flexible electronics. The conventional methods such as micro-Raman spectroscopy, are often constrained by factors like probing laser beam induced heating and substrate interactions. In the present work, we demonstrate a novel method to estimate the Young’s modulus, strain and thermal expansion co-efficient of MoS₂ multilayers using a bimaterial like micro-mechanical device made of MoS₂ and SiO₂. SiO₂ microcantilevers (MC) were fabricated using bulk micromachining technique and MoS₂ layers were grown on one side of the device by chemical vapor deposition method. Shift in resonance frequency due to the added MOS₂ layers on MCs was used to estimate the Young’s modulus of layered MoS₂. Similarly, growth induced curvature change of the bimaterial MCs was measured to estimate the interfacial stress between the MoS₂ multilayers and the substrate. From the measured temperature induced curvature changes, thermal expansion co-efficient of layered MoS₂ was estimated.