Low field magneto-tuneable photodetection in Dy³⁺ doped Co-Zn ferrite based heterojunctions

This study presents the fabrication and magnetically tunable photoresponse behavior of p⁺-Si/CZFO/AZO and p⁺-Si/CZFDO/AZO trilayer heterostructures prepared by radio frequency magnetron sputtering. The structural, morphological, optical, and magnetic characteristics of Co_0.7Zn_0.3Fe₂O₄ (CZFO) and Dy³⁺ doped Co_0.7Zn_0.3Fe₂O₄ (CZFDO) spinel ferrite thin films were studied thoroughly. Photoresponse characteristics of the fabricated trilayer devices under broadband illumination (39.6 [Formula: see text] [Formula: see text], 300-1100 [Formula: see text]) demonstrate that the CZFDO based photodetector exhibits nearly threefold higher photocurrent density ([Formula: see text]), faster rise ([Formula: see text]) and decay times ([Formula: see text]), and greater responsivity [Formula: see text] and specific detectivity ([Formula: see text]) compared to the CZFO based device at + 5 [Formula: see text] bias. The application of an external magnetic field (0 to 3000 [Formula: see text]) further enhances the photocurrent by promoting spin aligned carrier transport and reducing recombination losses, confirming magneto-photoelectric coupling. The values of [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text] also change significantly with the application of a magnetic field for both devices. The best obtained values of rise and fall times are [Formula: see text] and [Formula: see text] for the CZFDO based device at + 5 [Formula: see text] bias and 3000 Oe field. Interestingly, both devices retain partial photocurrent even after removing the field. These heterostructure devices with high photocurrent to dark current ratios and fast switching action can play the role of magnetically tunable broadband photodetectors, suitable for potential applications in magneto-optoelectronic sensors and spintronic devices.