Temperature and time stability of process-induced strain engineering on 2D materials

Abstract

Process-induced strain engineering is an effective method of crafting the strain state in 2D materials. Much like how it has been used in the fabrication of Si-based electronics, stressed thin films are deposited onto van der Waals-bonded 2D systems where relaxation of the stressor layer causes strain transfer into the 2D materials. This type of strain engineering can be used on a device-by-device level and be controlled for strain magnitude, compression or tension, uniaxiality or biaxiality, and directionality relative to crystal structure by varying film stress or geometry. One critical question in translating this technique to 2D materials is how temperature and time stable this strain engineering process is. In this work, we explore these factors through Raman spectroscopic mapping and photoluminescence spectroscopy ranging in temperatures from 293 to 4 K. It is shown that strain engineering with thin film stressors is equally persistent at all temperatures examined and time stable for a period of at least 14 months (the period of observation). These results suggest that process-induced strain engineering may be used to tune any number of interesting low-temperature properties in 2D materials and that any devices engineered in this way will have long-term stability for applications in electronics, optoelectronics, and beyond.