Optimizing the thermal annealing temperature: technological route for tuning the photo-detecting property of p-CuO thin films grown by chemical bath deposition method
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In the current work, CuO thin films (~ 110 nm) are grown by employing chemical bath deposition (CBD) method on Si substrate for fabricating the p-CuO/n-Si heterojunction photodetectors. The as-grown films are annealed at 250, 550 and 850 °C for 10 min in Ar ambient for tuning optoelectronic properties of the as-grown CuO thin films. Comparative study on systematic annealing of the film within 250–550 °C indicates a morphological change of the as-grown CuO film to nano-fiber type with its chemical composition remaining unchanged. A variation of refractive index and dielectric constant in the range of 2.65–2.93 and 7.2–9.7, and a change of absorption coefficient and bandgap from 1.33 × 105 to 6.06 × 105 cm− 1 and 1.5 to 2.16 eV have been observed. The current–voltage characteristics both in dark and illuminated conditions suggest that the annealing of CuO film at 550 °C provides the best performance in terms of photo-to-dark current ratio and photoresponsivity. A respective enhancement of 5.07 and 10% for the photo-to-dark ratio and photoresponsivity has been observed for the 550 °C annealed sample.
Miss. Jenifar Sultana and Somdatta Paul would like to acknowledge the DST inspire program and University Grants Commission (UGC), India, for providing financial support to pursue their research. The authors would also like to acknowledge the DST Purse program and Center of Excellence (COE), TEQIP for providing infrastructure and financial support to conduct this work.
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