Intense pulsed light annealing of CdS and Au-decorated CdS nanoparticles for high-performance, self-powered silicon-based heterojunction photodetectors

The enhancement of visible light responsivity in nanostructured heterojunction silicon photodetectors has attracted significant research interest. In this work, intense pulsed light (IPL) annealing was employed to improve the performance of CdS/Si and Au-decorated CdS/Si photodetectors fabricated via laser ablation. X-ray diffraction (XRD) confirms a substantial improvement in crystallinity of both CdS and Au-decorated CdS after IPL annealing. The particle size of the CdS increased from 78 to 100 nm and from 10 to 15 nm for Au-decorated CdS after annealing. The mobility of the CdS and Au-decorated CdS increases after annealing. The optical energy gap of CdS increases from 2.55 to 2.68 eV after annealing. Photoluminescence studies of CdS nanoparticles after annealing show the presence of an intense single peak at 450 nm. Structural and optical analyses reveal that IPL annealing reduced defects and enlarged the depletion layer width, giving a twofold responsivity increase from 0.19 to 0.36 A W⁻¹ at 520 nm for CdS/Si and 0.23 to 0.42 A W⁻¹ at 460 nm for Au-decorated CdS/Si. The obtained results indicated that IPL annealing was rapid and optimized heterojunction photodetectors. The energy band diagram of Au-decorated CdS/Si after annealing was constructed under illumination. The effect of aging time on the performance of the fabricated photodetectors was investigated.