Enhanced Dielectric Properties, and Optical Conduction of Amorphous Silicon Thin Films via Ag₂O Coatings

Abstract

Herein, amorphous silicon (a-Si) thin films are coated with Ag₂O films of thickness of 100 nm and 500 nm by the thermal evaporation technique for the purpose of enhancing their dielectric and optical conduction properties. The structural and morphological studies on the a-Si/Ag₂O films (a-SA-xx; xx is the thickness of Ag₂O layer) have shown the preferred growth of hexagonal Ag₂O onto a-Si with increased strained structure. The increased oxide layers thickness change the morphology from spherical grains to resembling interconnects as a wavy networks organized in a hexagonal or quasi regular patterns. Ag₂O coating remarkably induced the free carrier absorption in the infrared range of light, redshifted the energy band gap, increased the light absorption by 24 times, enhanced the dielectric constant by ~ 100% in a-SA-100 and 4000% in a-SA-500 films. The optical conductivity of a-Si is improved ~ 26 and 132 times in the IR range. In addition, treating a-SA-xx films as optical filters workable as terahertz band filters have shown their ability to perform as electro-optical systems exhibiting enhanced cutoff frequency, drift mobility and free carrier concentration values. The drift mobility and terahertz cutoff frequency of a-SA-500 films reached 29.89 cm²/Vs and 9.50 THz in the IR range of light. The features of Ag₂O coated amorphous Si films are promising for IR laser sensing and other electro-optical applications.