Electrothermal Properties of 2D Materials in Device Applications

Abstract

Abstract To continue downscaling transistors, new materials must be explored. Two-dimensional (2D) materials are appealing due to their thinness and bandgap. The relatively weak van der Waals forces between layers in 2D materials allow easy exfoliation and device fabrication but also result in poor heat transfer to the substrate, which is the main path for heat removal. The impaired thermal coupling is exacerbated in few-layer devices where Joule heat dissipated in the layers further from the substrate encounters additional interlayer thermal resistance before reaching the substrate, which results in self-heating and thermal degradation of mobility. This study explores the electro-thermal properties of five popular 2D materials (MoS2, MoSe2, WS2, WSe2, and 2D black phosphorous). We simulate various devices with self-heating with a range of gate and drain biases and examine the effects on mobility and change in device temperature. The effects are compared to the isothermal case to ascertain the impact of self-heating. We observe that Joule heating has a significant effect on temperature rise, layer-wise drain current, and effective mobility. We show that black phosphorous performs the best thermally, owing to its relatively high thermal conductance to the substrate, while WSe2 performs the best electrically. This study will inform future thermally aware designs of nanoelectronic devices based on 2D materials.