Composition dependent structural, morphological, optical and electrical properties of CdS:Co window layer grown by chemical bath deposition

Enhancing Photodetection Performance and Thermal Tolerance of CdS Thin Films through Cobalt (Co) Doping

“…The step-by-step procedure followed for both processes is elucidated, drawing upon earlier published work. [3,10,31] For all the Co-doped CdS films, the dark current (I d ) remained remarkably stable and extremely low (<0.2 μA), even when subjected to an applied bias as high as 30 V. This phenomenon is in contrast to the findings reported by Sivagamai, et al [20] and Maity, et al [40] for Co-doped CdS, where they observed an increase in the dark current with an escalating concentration of Co in the CdS thin film. depicted in Figure 3a, the photocurrent (I p ) exhibited intriguing behavior.…”

“…), which shift the band edge in the semiconductor to shorter wavelength side or higher energies as explained by Burstein-Moss (BM) effect. [20,38] In addition to this, a reduction in the crystallite size also responsible for shifting of the absorption edge to shorter wavelength or higher energies. The scanning electron microscopy (SEM) images shown in Figure 1e for pure CdS, 1 and 8 wt% Co-doped CdS also supports above findings via illustrating an increase in grain size in 1 wt% Co-doped CdS as compared with pure and highly doped CdS thin films.…”

“…[ 36 ] The band gap of Co‐doped CdS thin film, shown as a inset in Figure 1d, estimated using Tauc's formula illustrates a decrease in the band gap of 1 wt% Co‐doped film as compared with pure CdS thin film. [ 12 ] This reduction in the film's band gap may be due to two reasons; 1) the sp‐d exchange interaction between electrons in CdS and localized electrons in Co [ 20 ] ; and 2) increased grain size. [ 20 ] At higher doping concentrations, the band gap is found to increase with increasing Co concentration.…”

“…into a semiconductor material at substitutional site through doping is capable of minimizing lattice distortion and leads to stable structure. [ 15,20 ] This, in turn, exerts a profound influence on the material's electrical as well as photo‐conducting properties.…”

“…into a semiconductor material at substitutional site through doping is capable of minimizing lattice distortion and leads to stable structure. [15,20] This, in turn, exerts a profound influence on the material's electrical as well as photo-conducting properties. Now, as CdS is of semiconducting nature, it has a negative temperature coefficient (NTC) of resistance, [21,22] its utilization in the instruments required for combustion monitoring, geothermal, mining, gas, and oil exploration at high operating temperatures is difficult.…”