Influence of strain on thermal conductivity of silicon nitride thin films

We present a micro-electro-mechanical system-based experimental technique to measure thermal conductivity of freestanding ultra-thin films of amorphous silicon nitride (Si ₃N ₄) as a function of mechanical strain. Using a combination of infrared thermal micrography and multi-physics simulation, we measured thermal conductivity of 50 nm thick silicon nitride films to observe it decrease from 2.7 W (m K) ¹at zero strain to 0.34 W (m K) ¹at about 2.4% tensile strain. We propose that such strong strainthermal conductivity coupling is due to strain effects on fractionphonon interaction that decreases the dominant hopping mode conduction in the amorphous silicon nitride specimens.