Strain and Interference Synergistically Modulated Optical and Electrical Properties in ReS₂/Graphene Heterojunction Bubbles

Two-dimensional (2D) material bubbles, as a straightforward method to induce strain, represent a potentially powerful platform for the modulation of different properties of 2D materials and the exploration of their strain-related applications. Here, we prepare ReS2/graphene heterojunction bubbles (ReS2/gr heterobubbles) and investigate their strain and interference synergistically modulated optical and electrical properties. We perform Raman and photoluminescence (PL) spectra to verify the continuously varying strain and the microcavity induced optical interference in ReS2/gr heterobubbles. Kelvin probe force microscopy (KPFM) is carried out to explore the photogenerated carrier transfer behavior in both strained ReS2/gr heterobubbles and ReS2/gr interfaces, as well as the oscillation of surface potential caused by optical interference under illumination conditions. Moreover, the switching of in-plane crystal orientation and the modulation of optical anisotropy of ReS2/gr heterobubbles are observed by azimuth-dependent reflectance difference microscopy (ADRDM), which can be attributed to the action of both strain effect and interference. Our study proves that the optical and electrical properties can be effectively modulated by the synergistical effect of strain and interference in a 2D material bubble

In-Plane Optical Anisotropy and Linear Dichroism in Low-Symmetry Layered TlSe

In-plane anisotropy of layered materials adds another dimension to their applications, opening up avenues in diverse angle-resolved devices. However, to fulfill a strong inherent in-plane anisotropy in layered materials still poses a significant challenge, as it often requires a low-symmetry nature of layered materials. Here, we report the fabrication of a member of layered semiconducting A^IIIB^VI compounds, TlSe, that possesses a low-symmetry tetragonal structure and investigate its anisotropic light–matter interactions. We first identify the in-plane Raman intensity anisotropy of thin-layer TlSe, offering unambiguous evidence that the anisotropy is sensitive to crystalline orientation. Further <i>in-situ</i> azimuth-dependent reflectance difference microscopy enables the direct evaluation of in-plane optical anisotropy of layered TlSe, and we demonstrate that the TlSe shows a linear dichroism under polarized absorption spectra arising from an in-plane anisotropic optical property. As a direct result of the linear dichroism, we successfully fabricate TlSe devices for polarization-sensitive photodetection. The discovery of layered TlSe with a strong in-plane anisotropy not only facilitates its applications in linear dichroic photodetection but opens up more possibilities for other functional device applications

Contact Engineering of Molybdenum Ditelluride Field Effect Transistors through Rapid Thermal Annealing

Understanding and engineering the interface between metal and two-dimensional materials are of great importance to the research and development of nanoelectronics. In many cases the interface of metal and 2D materials can dominate the transport behavior of the devices. In this study, we focus on the metal contacts of MoTe₂ (molybdenum ditelluride) FETs (field effect transistors) and demonstrate how to use post-annealing treatment to modulate their transport behaviors in a controlled manner. We have also carried out low temperature and transmission electron microscopy studies to understand the mechanisms behind the prominent effect of the annealing process. Changes in transport properties are presumably due to anti-site defects formed at the metal–MoTe₂ interface under elevated temperature. The study provides more insights into MoTe₂ field effect devices and suggests guidelines for future optimizations