Ab initio study of elastic properties of orthorhombic cadmium stannate as a substrate for the manufacture of MEMS devices

Abstract

The elastic properties of the orthorhombic cadmium stannate (Cd2SnO4) were investigated using density functional theory, applying both energy-strain relationship (which is found in the literature) and stress-strain relationship (which we have developed in this study), both in the generalized gradient approximation and local density approximation (LDA) as implemented in the Quantum Espresso code. The results from both methods were found to be in good agreement with each other. However, the values for the stress-strain calculation were found to be relatively higher than those of the energy-strain and also, were those obtained from the LDA. The study found out that Cd2SnO4 possesses desirable elastic properties that are comparable to those of silicon, the dominant substrate material used in the manufacture of Microelectromechanical Systems. The bulk modulus was found to be nearly twice (more than 1.5 times) that of Si. Moreover, the material was found to be ductile, which when combined with the transparent nature that has been studied earlier and is available in the literature, can form a better substrate for the manufacture of transparent and flexible MEMS such as cardiopulmonary sensors, microbolometers, temperature and pressure sensors