Effect of Zn doping on optical properties and electrical conductivity-mechanism of Sb-Ge-Se chalcogenide glassy systems

Abstract

The present communication inspects the impact of zinc doping on the s optical, and electrical characteristics of bulk glassy samples made up of xZn-(0.1-x)Sb-0.2Ge-0.7Se (x = 0.01, 0.02, 0.03, 0.05). The X-ray diffraction patterns confirm that the samples are amorphous. In addition to various optical constants, the linear refractive index, and skin depth have been determined. The decreases in band gap energy values from 1.62 eV to 1.56 eV may be attributed to the rise in Unbach energy values from 0.15 eV to 0.32 eV. The obtained value of refractive indices also increases from 2.91 to 2.95 with the rising Zn content. By using the paradigm of Jonscher's universal power law and the Almond-West formalism, the underlying mechanisms of AC conductivity have been investigated. The AC conductivity increases with temperature and displays semiconducting characteristics. As the power-law exponent (s) reduces with increasing temperature, the correlated barrier hopping model is used to explain the AC conduction mechanism. DC conduction mechanism is described by Mott's and Greaves's variable range hopping model. The anticipated values of tiny polaron hopping energy (Whop) and hopping distance (Rhop) shed light on the increasing trend of DC conductivity with increased Zn concentration.