A profound analysis of structural, thermal, optical, and electrical properties of Cd50Pb30S20 composition for optoelectronic devices: implications of changes in film's thickness

摘要

In this framework, the ternary Cd50Pb30S20 bulk alloy and the derived-thin films at different thicknesses (d = 120, 180, 240, and 300 nm) were studied. DSC measurements were carried out at different heating rates from 5 to 20 K/min to extract thermal parameters in the temperature range of (300-700 K). (XRD) and (SEM) techniques showed polycrystalline CdS and PbS phases in the studied films. From optical measurement pathways (T, R), it was found that the films have the ability to block UV light and transmit up to 48 of light in the sub-pass range, which is at the beginning of the visible range and allows about 97 of the infrared through its surface. It was confirmed that orbital transition energies, also referred to as transport bandgaps or onset gaps, were associated with the fundamental absorption edge and the sub-absorption edge of the studied thin films. The optical constants (k and n) and the dispersion parameters (E-o and E-d) were determined. DC conductivity test in the temperature range (300-700 K) was discussed. Different models based on the typical hopping of charge carriers were used to determine the conduction mechanism. In the extended state region located in the high-temperature range, Arrhenius and Schnakenberg's models were used to extract the related parameters. While, Mott and Greaves's models were utilized to compute the electrical parameters in the hopping state region located in the low-temperature range. The Greaves VRH model provided the best insight into the conductivity pathways of the studied films in the low-temperature range.