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Keywords:
CuO nanoparticles; heterojunction; optoelectronics; visible-light photodetector; ZnO nanorods
Abstract
Optoelectronic devices have various applications in medical equipment, sensors, and communication systems. Photodetectors, which convert light into electrical signals, have gained much attention from many research teams. This study describes a low-cost photodetector based on CuO nanoparticles and ZnO nanorods operating in a wide range of light wavelengths (395. 464. 532. and 640 nm). Particularly, under 395 nm excitation, the heterostructure device exhibits high responsivity, photoconductive gain, detectivity. and sensitivity with maximum values of 1.38 A-W-1. 4.33. 2.58 x 1011 Jones, and 1934.5% at a bias of 2 V. respectively. The sensing mechanism of the p-n heterojunction of CuO/ZnO is also explored. Overall, this study indicates that the heterostructure of CuO nanoparticles and ZnO nanorods obtained via a simple and cost-effective synthesis process has great potential for optoelectronic applications.
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Introduction
Optoelectronics is a field to accelerate the development of many technologies in the future, such as solar cells [1.2], light-emitting diodes (LEDs) [3.4], laser diodes [5], and optical fibers [6]. Optoelectronics devices contribute to meeting requirements in telecommunications, medical equipment, sensors, and military services. Among those applications, photodetection is an attractive area because photodetectors are the critial component to convert photon energy into electrical signals based on a nonlinear interaction between electromagnetic field and material surface [7]. Currently, many scientists are studying this topic in order to apply photodetectors (PDs) to "Industry 4.0". which may include image sensors, biomedical imaging, manufacturing process control, environmental sensing, and optical sensors [8]. Various materials for photodetectors have been developed. Photodetectors can be classified into two main categories. namely PDs that work at a particular wavelength [9-14] and broadband PDs that work over a wide wavelength range [15]. Many researchers have focused on developing sensing materials operating in the visible-light region because this region is the biggest fraction of the solar spectrum (around 43%) [16-18]. Semiconductors are the heart of photodetectors as their bandgap allows for the absorption of photons in the desired wavelength range [19]. There are many semiconductor materials developed for this application. Among them, zinc oxide (ZnO) has been studied extensively over the last decades because of its large exciton binding energy of 60 meV at room...