Interface-driven phonon scattering and carrier dynamics in asymmetric GeS/GeSe van der Waals heterostructure

Abstract

Two-dimensional (2D) van der Waals (vdW) heterostructures, featured by the unique inverted asymmetric architectures, open new avenues for finely tuning electronic properties at the atomic scale. The structural versatility renders them as promising candidates for application in thermoelectrics (TEs), where the precise control of carrier dynamics and phonon transport is essential. By combining first-principles calculations and Boltzmann transport theory, the crystal structure, mechanical properties, thermal transport properties, and electronic transport properties of the 2D/2D GeS/GeSe vdW heterostructure are investigated in the current work. Comprehensive investigations of mechanical properties, phonon dispersion spectra, and ab initio molecular dynamics simulations collectively confirm the mechanical robustness, dynamic stability, and thermal durability of the 2D/2D GeS/GeSe vdW heterostructure, strongly underscoring its experimental feasibility. The GeS/GeSe vdW heterostructure exhibits a low lattice thermal conductivity of 1.57 W m−1 K−1 at 300 K owing to the enhanced interfacial phonon scattering. Concurrently, electronic transport assessments highlight the excellent carrier mobility and favorable band alignment within the GeS/GeSe heterostructure. Notably, the optimal dimensional figure-of-merits (ZTs) for p- and n-type doping circumstances reach 1.84 and 1.61 at 700 K, establishing the GeS/GeSe vdW heterostructure as a high-performance TE material.