CdSe thin films-based photodetector doped with Cu, In and Ga atoms: a comparative work

The present work demonstrates a comparison of performance of Cu, In and Ga-doped CdSe thin films-based photodetectors. Structural, morphological, optical and electrical investigation of Cu, In and Ga-doped CdSe thin films prepared by close space sublimation on glass slides is also achieved. It is obtained that Cu, In and Ga-doped CdSe thin films have a good crystal quality with a hexagonal structure in the preferred orientation along (002) plane. Morphological examination shows that Cu-doped CdSe thin films grow in the porous microstructure while In and Ga-doped CdSe films possess compact and uniform morphology without any voids. Transparency of In and Ga-doped CdSe films are higher than that of Cu-doped CdSe throughout the entire spectrum. Band gap values of all the samples are determined to be almost 1.72 eV. Photoluminescence data indicate that Ga-doped CdSe thin films display a deep level band at the lowest peak intensity, which is the indication of less defected structure. All the samples exhibit n-type conductivity. Additionally, the maximum carrier density and the minimum resistivity are reached for In-doped CdSe thin films as 1.75 × 1016 cm−3 and 6.12 Ω cm, respectively. Rise time of 28 ms and fall time of 25 ms are obtained for Cu-doped CdSe thin films-based photodetector, which are the fastest photoresponse within all the devices. Furthermore, Cu-doped CdSe thin films-based device has a responsivity of 1.20 × 10–2 A/W and a detectivity of 1.20 × 109 Jones that makes Cu-doped CdSe thin films-based device as a strong candidate for high sensitive photodetector applications.