Lai Jian-Ru, Wang Fang-Hsing, Liu Han-Wen, Kang Tsung-Kuei
Department of Electrical Engineering, National Chung Hsing University, Taichung 40227, Taiwan.
Graduate Institute of Optoelectronic Engineering, National Chung Hsing University, Taichung 40227, Taiwan.
Nanomaterials (Basel). 2025 Aug 8;15(16):1212. doi: 10.3390/nano15161212.
Ultraviolet (UV) and blue-light photodetectors are vital in environmental monitoring, medical and biomedical applications, optical communications, and security and anti-counterfeiting technologies. However, conventional silicon-based devices suffer from limited sensitivity to short-wavelength light due to their narrow indirect bandgap. In this study, we investigate the influence of precursor concentration on the structural, optical, and photoresponse characteristics of nanostructured CdS thin films synthesized via chemical bath deposition. Among the CdS samples prepared at different precursor concentrations, the best photoresponsivity of 21.1 mA/W was obtained at 2 M concentration. Subsequently, a p-n heterojunction photodetector was fabricated by integrating a spin-coated CuSCN layer with the optimized CdS nanostructure. The resulting device exhibited pronounced rectifying behavior with a rectification ratio of ~750 and an ideality factor of 1.39. Under illumination and a 5 V bias, the photodetector achieved an exceptional responsivity exceeding 10 A/W in the UV region-over six orders of magnitude higher than that of CdS-based metal-semiconductor-metal devices. This remarkable enhancement is attributed to the improved light absorption, efficient charge separation, and enhanced hole transport enabled by CuSCN incorporation and heterojunction formation. These findings present a cost-effective, solution-processed approach to fabricating high-responsivity nanostructured photodetectors, promising for future applications in smart healthcare, environmental surveillance, and consumer electronics.
紫外线（UV）和蓝光光电探测器在环境监测、医学和生物医学应用、光通信以及安全与防伪技术中至关重要。然而，传统的硅基器件由于其间接带隙窄，对短波长光的灵敏度有限。在本研究中，我们研究了前驱体浓度对通过化学浴沉积法合成的纳米结构硫化镉（CdS）薄膜的结构、光学和光响应特性的影响。在不同前驱体浓度下制备的CdS样品中，2 M浓度的样品获得了最佳的21.1 mA/W的光响应度。随后，通过将旋涂的硫氰酸铜（CuSCN）层与优化的CdS纳米结构集成，制备了一个p-n异质结光电探测器。所得器件表现出明显的整流行为，整流比约为750，理想因子为1.39。在光照和5 V偏压下，该光电探测器在紫外区域实现了超过10 A/W的优异响应度——比基于CdS的金属-半导体-金属器件高出六个数量级以上。这种显著的增强归因于通过掺入CuSCN和形成异质结实现的光吸收改善、有效的电荷分离以及增强的空穴传输。这些发现提出了一种经济高效的、溶液处理的方法来制造高响应度的纳米结构光电探测器，有望在未来的智能医疗、环境监测和消费电子产品中得到应用。
