A detailed comparative performance analysis of the Transition Metal Di-chalcogenides (TMDs) based strain sensors through experimental realisations and first principle calculations

Abstract

To date, most reports on the development of different Transition Metal Di-chalcogenide (TMDs) based strain sensors emphasize the qualitative analysis of the transduction mechanism of fabricated sensor devices based on a specific TMD. However, to the best of the author's knowledge, no reports are available on the systematic comparative performance analysis of different TMDs for strain sensing applications that correlate the sensing performance with electronic properties of individual TMDs. This limits the design-level understanding of TMD-based strain sensors and their performance optimization. In this context, this work demonstrates the fabrication and electrical characterization of strain sensors based on five TMDs (MoS2, MoSe2, SnSe2, NiSe2, and SnS2). Furthermore, the electronic properties of the individual TMDs are analysed using Density Functional Theory (DFT) based first-principle calculations and correlated with the experimentally observed sensing performance under applied strain. The strain sensors are modelled as the percolating networks of TMD nano-flakes, and the transduction mechanism is assessed as the modulations in the inter-flake quantum mechanical tunneling components and thereby overall conductivity of the network with applied strain. Subsequently, it has been demonstrated that the response of individual percolating networks of TMDs depends on the carrier concentrations, energy bandgap, and Density of states (DOS) for a specific applied strain. The influence of these properties on the transduction mechanism is theoretically analysed, leading to a clear casual correlation between the experimental observed Gauge factors and the theoretically calculated energy bandgap and conduction band DOS/effective masses. The higher gauge factors measured experimentally are for selenides-based TMDs, which also collaborates with the simulations studies suggesting that the materials with lower bandgap and higher DOS are best suited for physical sensing applications.