Electrothermal properties of 2D materials in device applications

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 between layers and to the substrate, which is the main path for heat removal, resulting in self-heating and thermal degradation of mobility. This study explores the electrothermal 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, layerwise 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.