Vitamin D3 acts as a crucial biomarker for various diseases. Current methods for vitamin D3 detection are time-consuming, expensive, and require trained personnel. We report a simple and cheap photodetector (PD)-based vitamin D3 detection technique for the first time using Ag nanoparticles-covered Er-doped TiO2 nanowires. The operational stability of the device was tested under the dark as well as the UV light illumination. Vitamin D3 solution produced absorption bands at 222 and 280 nm, respectively. The PD current density varied from 1.29 × 10 − 4 A / cm2 to 1.74 × 10 − 4 at −4 V for pure ethanol solution and 20 pg / ml D3 solution, respectively (under 220 nm illumination). The average absolute current values were reduced from 3.25 nA (220 nm) and 2.9 nA (340 nm) for 5 pg / ml to 2.95 nA (220 nm) and 2.54 nA (340 nm) for 30 pg / ml D3 solution, respectively. The current gradually increased up to 3.34 nA (220 nm) and 2.7 nA (340 nm) as the concentration was increased up to 80 pg / ml. The PD current/vitamin D3 concentration decreases exponentially from 0.58 to 0.03 nA / g / ml) for 5 and 80 pg / ml, respectively, under 220 nm excitation, from which an unknown concentration of vitamin D3 can be obtained.
UV photodetector have been successfully implemented in various applications like ozone sensing, communication, astronomy and flame detection etc. Zn(Mg)O is a wide band gap material with high excitonic binding energy at room temperature thus making it a promising material in optoelectronic industries. In the present work, we are achieving increased photocurrent and high responsivity in UV-A regime with post growth UV-ozone treatment from photodetector fabricated using RF sputtered ZnMgO thin film. The thin film was deposited on semi-insulating silicon wafer at 400C for 20 min followed by 70 min UV-Ozone treatment. The final step was to fabricate an interdigitated electrode on the processed samples. More than two times enhancement of photocurrent was observed after UVO treatment. Noteworthy responsivity values of 22 A/W and 67 A/W were measured from as-deposited and UVO annealed photodetector, respectively at 380 nm with an applied bias of -5 V bias. However, the measured detectivity values for as grown and UV-O annealed sample was 1.3 × 1013 and 2.7 × 1013, respectively. Noise equivalent power in as-deposited sample and UVO treated sample was estimated to be 2.4 × 10-12 W/√Hz and 1.1 × 10-12 W/√Hz respectively. Photo detector fabricated with UV-O annealing exhibited good switching behaviors with 37 ms and 30 ms rise and fall time, respectively.
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