Investigation of Energy Band Gap of Amorphous Se₈₀Te_20-XCd_X (X= 0, 4, 8, & 12) Glassy Chalgogenides for Optoelectronic Devices

We have included Cd in the current Se-Tebinary system. The incorporation of additional third element Cd expands the glass developing region and constructs compositional and configurationally disorder in the Se-Te system. Optical measurements constitute the most important means to calculate its optical constants such as energy band-gap (Eg) refractive index (n) and extinction coefficient (k), transmittance (T), and dielectric constants. X-ray diffraction (XRD) measurement were done to confirm the glassy behavior of the prepared alloy. Thin films were developed by the vacuum evaporation of the samples from molybdenum boat in a vacuum chamber at low pressure of 10<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-5</sup> Torr on a substrate, at room temperature. The measured thickness of the film of our sample was found 3000A<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sup>. The optical properties as a function withthe wavelength are measured with A JASCO, V-500, UV/VIS/NIR computerized spectrophotometer. The quantitative measurement of the refractive-index n, extinction co-efficient k, dielectric constant (real and imaginary parts) and absorption coefficient (α) were determined from the studied data of the prepared thin films. The absorption coefficient (α) is used to compute the optical energy gap (Eg), which is increasing by adding the cadmium contents in the Se-Te-Cd system in the prepared materials for the samples Also it comes out that the materials has an indirect band gap characteristics.