First-principles design of MSi2N4/WSi2N4 (M = Ti, Zr, Hf): Structural stability, thermal, electronic and optical properties

The family of two-dimensional MA2Z4 heterostructures has received increasing attention in recent years. To investigate the structural stability, electrical structure, optical characteristics, and thermal properties (M = Ti, Zr, and Hf) of MSi2N4/WSi2N4, we have carried out first-principles calculations. The dynamic stability of MSi2N4/ WSi2N4 (M = Ti, Zr, and Hf) is confirmed by phonon spectrum analysis. ZrSi2N4/WSi2N4 and HfSi2N4/WSi2N4 have indirect band type with bandgap of 0.37 eV and 0.34 eV, respectively, while TiSi2N4/WSi2N4 exhibits metallic property. At room temperature (300 K), the relative thermal values (CV) of MSi2N4/WSi2N4 (M = Ti, Zr and Hf) vary between 100 and 212.5 JK-1mol- 1. Moreover, ZrSi2N4/WSi2N4 and HfSi2N4/WSi2N4 have light absorption qualities below 12 % in both the Ultraviolet and Infrared areas. The MSi2N4/WSi2N4 materials (where M = Ti, Zr, and Hf) exhibit exceptional characteristics, positioning them as promising candidates for applications in thermoelectric and nanoelectronic fields.