Layer hybridized exciton–plasmon resonances for enhanced dispersion modes in CuS:Al nanostructured films

Abstract

The coupled excitonic and localized surface plasmon resonant (LSPR) properties of two-dimensional (2D) quantum materials can reduce dielectric screening effects to create a wide range of applications in next-generation nanoelectronics and optoelectronic devices. Here, we report p-type CuS nanostructures with Al-doping to diverge inter-layer exciton and intra-layer plasmon transitions for tuneable dielectric screening phenomena. The effect of doping has developed distortions in spatial alignment to create exfoliated character in dual assemblies of nanoflakes and vertical nanorods. The Drude–Lorentz model has been applied to the diffuse reflectance spectrum for befittingly resolved hybrid states that yield information on enhanced dispersion modes and optical constants. The devised epsilon-near zero (ENZ) modes in permittivity have been shifted and extended towards the far infrared spectral region for the Al-doped nanostructures. Corroboratively, the linear absorption spectra have been fitted with Gaussian peaks to distinguish the in-between variations of exciton–plasmon periodic energy exchange. Furthermore, Raman spectroscopy, Hall measurements and X-ray photoelectron spectroscopy, respectively, corroborate the inter/intra-layered interactions, charge carrier dynamics, element vacancies and valence band structure of the CuS:Al system. Our experimental results and theoretical interpretations provide important physical evidence to improve the tuneable functionalities and performance of optoelectronic devices.