Genetic algorithm designed multilayered Si₃N₄ nanowire membranes hybridized by dielectric wide-range tunable CVD graphene skin for broadband microwave absorption

Nowadays, the dispersion characteristics limit the broadband performance of single-layer homogeneous absorbing materials. A multilayer impedance matching structure (MIMS) is capable of optimizing the impedance matching characteristics of the broadband electromagnetic wave (EMW), thereby broadening the effective absorption band (EAB). Consequently, the availability of a database with differentiated characteristics is a crucial prerequisite for the realization of MIMS design. Herein, graphene (Gr)-skinned Si₃N₄ nanowires were prepared via a chemical vapor deposition (CVD) process. Moreover, the formation of a strong interfacial polarization between Si₃N₄ and Gr can optimize the samples within the database. Furthermore, a wide-range of defect content (0.80–2.35 of I_D/I_G) and dielectric loss (0.03–1.5 of tanδ) modulation was achieved through the manipulation of the CVD deposition process. A two-layer structure with a thickness of only 5 mm was rapidly designed based on a wide-range modulation and genetic algorithm. This structure exhibited an EAB of up to 12.48 GHz according to measurement of arc method, which is a significant widening of 5.6 GHz compared to the EAB of the single-layer structure. The proposed integrated design of wide-range modulation of dielectric properties and intelligent optimization algorithm of macrostructure is expected to further broaden the EAB of dielectric absorbing materials and become a new design paradigm.