Optical, dielectric and electrical properties of Ba/Sb nanosheets designed for electro-optical application

Abstract

Herein, stacked nanosheets of barium and antimony are fabricated using a vacuum deposition technique under a vacuum pressure of 10-5 mbar onto cleaned glass substrates. The Zintl Ba/Sb nanosheets exhibit an amorphous nature of growth with equal atomic contents. Notably, they present interesting properties such as low average roughness, high light transmittance and absorption, and low reflectance. Two optical transitions within energy bands with values of 3.40 eV and 0.75 eV are determined for these stacked nanosheets. Additionally, Ba/Sb nanosheets displayed dielectric lens and optical filter characteristics with high optical conductivity exceeding 5.0 (Ωcm)-1, 20 (Ωcm)-1, and 100 (Ωcm)-1 in the infrared, visible, and ultraviolet ranges of light, respectively. The optical conductivity parameters, including the free charge carrier density, drift mobility, and plasmon frequency, exhibit values in the ranges of 1.3-25×1019 cm-3, 3.53-9.41 cm2/Vs, and 3.92-17.18 GHz, respectively. Moreover, Ba/Sb nanosheets display characteristics of terahertz band filters, demonstrating terahertz cutoff frequency values of 18-100 THz in the incident photon energy range of 1.13-3.64 eV. On the other hand, temperature-dependent electrical conductivity measurements on these stacked nanosheets reveal the domination of two impurity levels centered at 136 meV and 500 meV, with one being dominant below and the other above 380 K, respectively. The features of the Ba/Sb nanosheets reported here highlight their potential as optical filters, surface plasmon resonators, and terahertz band filters.