Enhanced carrier mobility in MoSe₂ by pressure modulation

Two-dimensional (2D) materials hold great potential for the development of next-generation integrated circuits (ICs) at the atomic limit. However, it is still very challenging to build high performance devices. One of the main factors that limit the incorporation of 2D materials into IC technology is their relatively low carrier mobility. Thus, the engineering strategies that focus on optimizing performance continue to emerge. Herein, using a spatiotemporal resolved pump-probe setup, the carrier transport performance and relaxation process of few-layer and bulk MoSe₂ under pressure were investigated nondestructively and simultaneously. Our results show that pressure can tune the transport performance effectively. In particular, under pressure regulation, the carrier mobility of the bulk MoSe₂ increases by ~ 4 times; meanwhile, the carrier lifetimes of the samples become shorter. Although the processes almost return to their initial state after the pressure release, it is still surprising to see that the carrier mobilities of few-layer and bulk MoSe₂ are still ~ 1.5 and 2 times enhanced, and carrier lifetimes are still shorter than the initial state. Combined with the Raman spectra under pressure, we consider that it is caused by the enhanced layer coupling and lattice compression. The combination of enhanced mobility and shortened lifetime in MoSe₂ under pressure holds great potential for optoelectronic applications under the deep ocean and deep earth.