Intrinsic and Strain-Dependent Properties of Suspended WSe₂ Crystallites toward Next-Generation Nanoelectronics and...

Two-dimensional (2D) layered materials exhibit great potential for high-performance electronics, where knowledge of their thermal and phononic properties is critical toward understanding heat dissipation mechanisms, considered to be a major bottleneck for current generation nanoelectronic, optoelectronic, and quantum-scale devices. In this work, noncontact Raman spectroscopy was used to analyze thermal properties of suspended 2D WSe₂ membranes to access the intrinsic properties. Here, the influence of electron-phonon interactions within the parent crystalline WSe₂ membranes was deciphered through a comparative analysis of extrinsic substrate-supported WSe₂, where heat dissipation mechanisms are intimately tied to the underlying substrate. Moreover, the excitonic states in WSe₂ were analyzed by using temperature-dependent photoluminescence spectroscopy, where an enhancement in intensity of the localized excitons in suspended WSe₂ was evident. Finally, phononic and electronic properties in suspended WSe₂ were examined through nanoscale local strain engineering, where a uniaxial force was induced on the membrane using a Au-coated cantilever within an atomic force microscope. Through the fundamental analysis provided here with temperature and strain-dependent phononic and optoelectronic properties in suspended WSe₂ nanosheets, the findings will inform the design of next-generation energy-efficient, high-performance devices based on WSe₂ and other 2D materials, including for quantum applications.