Enhancing the optoelectronic properties of low-cost nebulizer spray pyrolysis (NSP) prepared ZnS thin film through praseodymium doping for photodetector applications

Abstract

In this report, ZnS and ZnS:Pr (1, 3, and 5 wt% of Pr) thin films were coated onto the glass substrates by using the low-cost nebulizer spray pyrolysis (NSP) technique. Various characterization techniques were employed to analyze the structural, morphological, optical, and photosensing properties of the prepared samples. The X-ray diffraction results show that the ZnS and ZnS:Pr samples exhibit hexagonal wurtzite structure having preferential growth along the (002) plane which belongs to the P63mc space group. No secondary phases were detected in all the coated thin film samples. The maximum crystallite size of 36 nm was observed for ZnS:Pr1% sample. The SEM analysis revealed that the samples exhibit agglomerated grains and the EDX spectrum of the ZnS:Pr(1 %) sample showed the presence of Zn, S, and Pr elements. The UV–vis absorption spectrum of the ZnS:Pr1% sample revealed that it has higher absorption in the UV region and a decrease in bandgap is noticed among the fabricated samples. The PL spectra showed a highly intense emission line of around 489 nm and a weak UV emission of around 385 nm for all the films. The I-V characteristics of the prepared thin films show that the ZnS:Pr1% sample has higher photosensing properties of responsivity, photoresponse, External Quantum Efficiency (EQE), and the detectivity values of 5.30 × 10-3 AW−1, 5.27, 1.70 %, and 3.76 × 109 Jones, respectively suggesting the sample might be well suited for the UV photodetector applications.