Chunyang Kong

Transparent conductive oxide (TCO) films are crucial in optoelectronic devices, such as photodetectors, due to their unique blend of transparency and electrical conductivity. ZnO is a top choice for TCOs owing to its excellent properties, non-toxicity, and cost-effectiveness. In this work, we explore the potential of carbon doping to enhance the electrical properties of ZnO films for transparent conductive applications. Our findings reveal that C-doped ZnO (ZnO:C) films retain the pristine high quality and surface morphology despite an increase in defects with higher C doping. Notably, C doping does not compromise the visible light transmittance of ZnO films, while inducing a gradual increase in optical bandgap, indicative of the typical Burstein–Moss effect. As carbon doping increases, the ZnO:C films exhibit improved carrier concentration, lower resistivity, and sustained high mobility, achieving optimal performance with an electron concentration of 3.73 × 1019 cm−3, resistivity of 3.69 × 10−3 Ω cm, and mobility of 46.08 cm2 V−1 s−1. Finally, we utilized ZnO:C films as a transparent electrode material in ε-Ga2O3-based photodetector, achieving the development of transparent device and attaining high-performance solar-blind detection capabilities. This work provides a strategy for developing a transparent conductive oxide, with ZnO:C emerging as a promising rival to IIIA-doped ZnO for optoelectronic applications.

One of the most important applications of photodetectors is as sensing units in imaging systems. In practical applications, a photodetector array with high uniformity and high performance is an indispensable part of the imaging system. Herein, a photodetector array (5 × 4) consisting of 20 photodetector units, in which the photosensitive layer involves preprocessing commercial ε-Ga₂O₃ films with high temperature annealing, have been constructed by low-cost magnetron sputtering and mask processes. The ε-Ga₂O₃ ultraviolet photodetector unit shows excellent responsivity and detectivity of 6.18 A/W and 5 × 10¹³ Jones, respectively, an ultra-high light-to-dark ratio of 1.45 × 10⁵, and a fast photoresponse speed (0.14/0.09 s). At the same time, the device also shows good solar-blind characteristics and stability. Based on this, we demonstrate an ε-Ga₂O₃-thin-film-based solar-blind ultraviolet detector array with high uniformity and high performance for solar-blind imaging in optoelectronic integration applications.

In recent years, transparent electrode materials have had a positive effect on improving the responsivity of photodetectors by increasing the effective illumination area of devices due to their high transmittance. In this work, by using radio frequency magnetron sputtering and simple mask technology, an amorphous Ga₂O₃-based solar-blind UV photodetector with graphitic carbon (C) electrodes was created. The device exhibits a high responsivity of 16.34 A/W, an external quantum efficiency of 7979%, and excellent detectivity of 1.19 × 10¹³ Jones at room temperature under a light density of 5 μw/cm². It has been proved that C electrodes can replace the traditional noble metal electrode. Additionally, the potential of the transparent photodetector array in solar-blind imaging is explored. We believe that the present study will pave the way for the preparation of a fully transparent and high-response solar-blind ultraviolet photodetector array.

Recently, as an emerging material, ultrawide bandgap Ga₂O₃ has been investigated extensively in solar-blind deep-ultraviolet (DUV) photodetectors (PDs). High sensitivity and signal-to-noise ratio of PDs are essential for the detection of solar-blind DUV signals; however, such factors are often not mutually compatible. In the present study, an amorphous/monoclinic homogeneous mixed-phase structure was demonstrated to be significantly beneficial in enhancing the comprehensive performance of Ga₂O₃ solar-blind DUV PDs, especially with respect to sensitivity and the signal-to-noise ratio. Further experimental and theoretical findings provide insights on the transport mechanism of enhanced performance in the mixed-phase Ga₂O₃ solar-blind DUV PD. For effectively separating the photogenerated carriers, a type-II band alignment between amorphous and crystalline Ga₂O₃ can be exploited. Furthermore, the change of the barrier height of the mixed-phase interface also has a significant impact on the transport properties of the mixed-phase Ga₂O₃ PD. Additionally, the potential applications of mixed-phase Ga₂O₃ PD in high-voltage corona discharge were explored, and clear and stable corona discharge signals were obtained. The results of the present study may promote understanding of DUV photoelectronic devices with various mixed-phase Ga₂O₃ materials and provide an efficient approach for promoting comprehensive performance in future solar-blind detection applications.

The construction of heterojunctions has attracted considerable attention among the various strategies of water-splitting for hydrogen evolution due to their band structure advantages. In this research, we combined chemical vapor deposition and pulsed laser deposition to fabricate MoS₂/g-C₃N₄ heterojunction films on indium-tin oxide glass substrates, and we studied the photoelectrochemical (PEC) performance. The x-ray diffraction, x-ray photoelectron spectroscopy (XPS), and scanning electron microscope characterizations suggested the successful preparation of MoS₂/g-C₃N₄ heterojunction films. In particular, the shifts of the peak positions in the XPS spectra indicated the formation of a strong interaction between the g-C₃N₄ and MoS₂ films. After depositing MoS₂ on the g-C₃N₄ film, the visible-light absorption was enhanced and broadened, the electrical conductivity improved, and the intensity of the photoluminescence peak decreased. As a result, the greater generation, faster transport, and lower recombination rate of electrons and holes caused the heterojunction films to show higher PEC performance. More importantly, the obtained MoS₂/g-C₃N₄ film was confirmed to be an n–n type heterojunction and to have a typical type-II band structure, which could indeed suppress the recombination and promote the separation, transfer, and transport of photogenerated electron–holes. Finally, the obtained MoS₂/g-C₃N₄ film successfully achieved the overall water-splitting and the H₂ evolution rate when the visible-light radiation reached 252 µmol/h.

氧化镓(Ga₂O₃)纳米材料在紫外透明电极、高温气体传感器、日盲紫外探测器和功率器件等领域具有巨大的应用潜力, 而实现高结晶质量和尺寸形貌可控的Ga₂O₃纳米材料是关键. 本文通过水热法制备了不同尺寸的羟基氧化镓(GaOOH)纳米棒、纳米棒束和纺锤体, 经后期高温煅烧均成功转变为高质量单晶β-Ga₂O₃纳米材料并较好地保留了原始GaOOH的形态特征. 利用X射线衍射(XRD)、拉曼散射光谱(Raman)和场发射扫描电子显微镜(FE-SEM)等表征手段系统研究了前驱液的pH值大小和阴离子表面活性剂浓度对GaOOH和β-Ga₂O₃纳米材料晶体结构和表面形貌的影响, 并深入探讨了不同条件下GaOOH纳米材料的生长机制. 此外, 室温光致发光谱(PL)测试发现不同形貌的β-Ga₂O₃纳米材料均展现出典型的蓝绿色发射峰和尖锐的红光发射峰, 与纳米材料中本征缺陷的存在密切相关. 上述研究结果为未来实现高质量β-Ga₂O₃纳米材料的可控制备提供了有益参考.