Enhancing the Linear/Nonlinear Optical Properties of MoSe₂ via Third-Generation Semiconductor Nanoheterojunctions for Nano-Optoelectronic Devices

Abstract

Of late, it has been recognized that both the band gap and carrier mobility play crucial roles in the linear/nonlinear optical applications of nanolayered two-dimensional van der Waals (vdW) transition-metal disulfide compounds. Due to their unique anisotropic physics and twisted octahedral structure, MoSe 2 nanofilms have emerged as a focal point of research. This study focuses on the growth of MoSe 2 nanofilms via magnetron sputtering on various third-generation semiconductor nanofilms (AGZ: AlN, Ga 2 O 3 , and ZnO). The resulting nanocomposite films exhibit remarkably fast carrier dynamics. Morphological analysis using scanning electron microscopy (SEM) and finite-difference time-domain (FDTD) simulation confirmed the structural characteristics and revealed significant changes in electric, magnetic, and polarization fields within the nanoheterojunction films upon stress application. Moreover, these findings highlight evident light-matter interaction and efficient carrier transport. In addition, the linear and nonlinear optical absorption characteristics of MoSe 2 /AGZ were investigated along with the dynamic processes of charge separation, transfer, and energy transfer at the interface of the heterojunction. Furthermore, an energy-level model for the charge transition process under light irradiation was established. The nonlinear absorption coefficient (NLA) of MoSe 2 nanoheterojunctions is in the range of 10 −2 to 10 −3 cm/W, which is 10 to 100 times higher than that of pure material. Additionally, by evaluating the figure-of-merit (FOM) performance index for MoSe 2 nanoheterojunctions, we discovered that its ultrafast NLA behavior can be utilized in devices such as all-optical switches. This provides a theoretical foundation for the fabrication of functional heterojunctions.