近日，郑州大学单崇新团队以「Highly sensitive diamond X-ray detector array for high-temperature applications」¹为题在Chip上发表研究论文，利用金刚石实现了可在高温环境下工作的高灵敏度X射线探测阵列。第一作者为豆文杰，林超男和范伟为共同第一作者，通讯作者为杨珣、周维民、单崇新。Chip是全球唯一聚焦芯片类研究的综合性国际期刊，是入选了国家高起点新刊计划的「三类高质量论文」期刊之一。

X射线以其短波长和高能量，在医学成像、工业探伤、晶体结构分析以及安全筛查等多个领域得到了广泛应用²⁻³。然而，这些应用的效果高度依赖于高性能和稳定的X射线探测器⁴。目前，由于材料和设备检测机制的限制，开发兼具高灵敏度、快速响应和稳定性的探测器仍然面临挑战⁵⁻⁶。本文研究中，作者利用单晶金刚石构建了一个10×10 X射线探测器阵列，并通过不对称夹层电极结构提升了探测器的灵敏度。该金刚石X射线探测器阵列表现出了卓越的探测性能和高温稳定性。

图1 | 金刚石X射线探测器阵列的制作工艺。a, 制造工艺流程图。b, 探测器阵列示意图。c, 单个探测器单元示意图。d, 实物图。

制造过程包括几个步骤：首先，通过光刻法和磁控溅射法在金刚石正面沉积了10×10个银电极，每个电极的尺寸为850 mm×850 mm，电极间距为120 mm。接着，在金刚石背面沉积了Ti/Au电极。为了减少相邻像素之间的串扰，采用激光切割在银电极之间切割出沟槽。这些沟槽有效抑制了载流子的横向传输，从而减少了像素间的串扰，提升了探测器的光电性能和图像清晰度。

图2 | 金刚石X射线探测器的灵敏度检测极限以及高温下的光电性能。a, 不同偏置电压下探测器的灵敏度依赖曲线。b, 40 V偏置下信噪比与剂量率的关系。c, 不同温度黑暗环境和32.22 nGy s⁻¹剂量率下的I-V特征曲线。d, 不同温度下的光电流和暗电流。

图2展示了金刚石X射线探测器在不同条件下的性能。结果表明在50 V偏置电压下，灵敏度响应为14.3 mC Gy⁻¹ cm⁻²。40 V偏置下，信噪比等于3时的检测阈值为4.9 nGy s⁻¹。在27~450 ℃温度范围内光电流随着温度升高而增加。在62.83 nGy s⁻¹ X射线剂量率下光电流和暗电流均表现出良好的重复性。

图3 | X射线成像。a, X射线检测成像系统示意图。b-d, 分别在室温、150 ℃和260 ℃下的成像结果。

为了评估金刚石X射线探测器阵列的成像能力，搭建了一个X射线成像系统，如图3a所示。该系统包括X射线源、镀铅掩蔽板、金刚石光电探测器阵列和电流采集系统。X射线源和探测器阵列之间放置了带有「T」、「H」和「+」中空图案的镀铅掩蔽板。金刚石X射线探测器阵列将检测到的不同剂量率的X射线转换为电信号，并通过半导体分析仪收集输出电流。探测器阵列在室温、150 ℃和260 ℃下的成像结果如图3b-d所示。

总结，本文开发了一种10×10单晶金刚石X射线探测器阵列。通过采用不对称电极结构和激光切割加工的沟槽，显著提升了探测器的性能。该探测器在50 V偏置下展现出18312的光暗电流比、14.3 mCGy⁻¹ cm⁻²的灵敏度和4.9 nGy s⁻¹的检测极限，达到当前金刚石X射线探测器中的最佳水平。探测器还具有优异的均匀性和稳定性，能够在高达450 ℃的高温下有效探测X射线，拓展了其在恶劣环境下的应用潜力。

Highly sensitive diamond X-ray detector array for high-temperature applications¹

X-rays, which have short wavelengths and high energy, have been widely utilized in various fields, such as medical imaging, industrial flaw detection, crystal structure analysis, and security screening²⁻³. The effectiveness of these applications relies on the availability of high-performance and robust X-ray detectors⁴. However, the development of detectors that combine high sensitivity, rapid response rates, and stability is a difficult task due to limitations in materials and device detection mechanisms⁵⁻⁶. In this work, a 10×10 X-ray detector array was constructed from single-crystal diamond for the first time. An asymmetric sandwich electrode structure was employed to enhance the detector sensitivity. The diamond X-ray detector array exhibits impressive performance metrics.

Fig. 1 | Fabrication process of the diamond X-ray detector array. a, Flow chart for the fabrication processes of the diamond detector array. b, Schematic diagram of the diamond detector array. c, Schematic diagram of the diamond detector cells. d, Photograph of the diamond detector array.

The fabrication of the diamond detector array involves several steps, as shown in Fig. 1a. First, 10×10 Ag electrodes are deposited on the front side of the diamond using lithography and magnetron sputtering. Each Ag electrode had a size of 850 μm×850 μm, and the electrode spacing was 120 μm. Next, a Ti/Au common electrode was prepared on the back side of the diamond using magnetron sputtering. To prevent crosstalk between adjacent pixels, trenches are carved between Ag electrodes using laser cutting. A schematic diagram of the diamond detector array is shown in Fig. 1b-c. A photograph of the entire array is shown in Fig. 1d. These trenches effectively suppress the lateral transport of carriers and thus reduce crosstalk between pixels, which is crucial for improving the optoelectronic performance and obtaining clear images of diamond detector arrays.

Fig. 2 | Photoelectric properties of the diamond X-ray detectors. a, Sensitivity dependence curves of the detectors at different bias voltages.b, SNR as a function of the dose rate at 40 V bias. c, I–V characteristic curves at different temperatures in the dark and at a dose rate of 32.22 nGy s⁻¹.d, Comparison of light and dark current at different temperatures at a bias of 30 V.

Fig. 2a shows the bias voltage versus response sensitivity curve, showing a sensitivity response of 14.3 mC Gy⁻¹ cm⁻² at a bias voltage of 50 V. Fig. 2b shows the signal-to-noise ratio (SNR) with respect to the dose rate, indicating that the detection threshold determined by the intercept of the curve at SNR = 3 is 4.9 nGy s⁻¹. Fig. 2c shows the I-V curves of the detector at temperatures ranging from 27 to 450 °C. It shows that the photocurrent increases continuously with increasing temperature. Fig. 2d compares the photocurrent and dark current with temperature for an x-ray dose rate of 62.83 nGy s⁻¹. Both photocurrent and dark current show good repeatability with increasing and decreasing temperature.

Fig. 3 | X-ray imaging. a, Diagrammatic sketch of the X-ray detection imaging system.b–d, Imaging results at room temperature, 150 ℃ and 260 ℃, respectively.

To investigate the imaging capability of the diamond X-ray detector array, an X-ray imaging system is built. The system consists of an X-ray source, a lead-plated masking plate, a diamond photodetector array, and a current collection system, as shown in Fig. 3a. Lead-plated masking plates with hollow patterns of 「T」, 「H」, and 「+」 are placed between the X-ray source and the detector array. The diamond X-ray detector array converts the detected X-rays of different dose rates into electrical signals, and the output currents of the photodetector array are collected using a semiconductor analyzer. The imaging results of the detector array at room temperature, 150 ℃ and 260 ℃ are shown in Fig. 3b-d.

A 10×10 X-ray detector array was developed utilizing single-crystal diamond for the first time. To enhance the performance of the detector, an asymmetric electrode structure was implemented, and trenches were created through laser cutting to prevent crosstalk between pixels. The diamond X-ray detector array demonstrated a light/dark current ratio of 18312, a sensitivity of 14.3 mC Gy⁻¹ cm⁻² and a detection limit of 4.9 nGy s⁻¹ at 50 V bias. These results are among the best values ever reported for diamond-based X-ray detectors. Notably, the device shows exceptional uniformity, stability, and the ability to detect X-rays at high temperatures up to 450 ℃, which may push forward the application of such devices in harsh environments.

参考文献

1. Dou, W. et al. Highly sensitive diamond X-ray detector array for hightemperature applications.Chip 3, 100106 (2024).

2. Yi, L. et al. X-ray-to-visible light-field detection through pixelated colour conversion. Nature 618, 281-286 (2023).

3. Sakhatskyi, K. et al. Stable perovskite single-crystal X-ray imaging detectors with single-photon sensitivity. Nat. Photonics 17, 510-517 (2023).

4. Chen, J. et al. High-performance X-ray detector based on single-crystal β-Ga2O3:Mg. ACS Appl. Mater. Interfaces 13, 2879-2886 (2021).

5. Bian, Y. et al. Spatially nanoconfined N-type polymer semiconductors for stretchable ultrasensitive X-ray detection. Nat. Commun. 13, 7163 (2022).

6. He, Y. et al. Sensitivity and detection limit of spectroscopic-grade perovskite CsPbBr3 crystal for hard X-ray detection. Adv. Funct. Mater. 32, 24(2022).

论文链接：

https://www.sciencedirect.com/science/article/pii/S2709472324000248

作者简介

豆文杰，本科毕业于河南理工大学机械学院，目前在郑州大学物理学院攻读博士学位，研究方向主要为金刚石光电器件。

Wenjie Dou completed his undergraduate studies at the School of Mechanical Engineering, Henan University of Science and Technology. He is currently pursuing a Ph.D. at the School of Physics, Zhengzhou University, with a research focus on diamond optoelectronic devices.

单崇新，郑州大学教授，博士生导师，郑州大学副校长，教育部「长江学者奖励计划」特聘教授、国家杰出青年基金获得者、中组部万人计划「青年拔尖人才」、人社部「百千万人才工程」及国家有突出贡献中青年专家、中国青年科技奖获得者。主要从事金刚石光电材料与器件研究，发表学术论文400余篇，被引用16000余次。研究成果获河南省自然科学一等奖（排名第1）、吉林省自然科学一等奖（排名第2）、吉林省科技进步一等奖（排名第2）、吉林省自然科学学术成果二等奖1项（排名第1）。先后主持国家重大仪器研制项目、国家自然科学基金委-河南省联合基金重点项目等科研项目。

Chong-Xin Shan is a professor and doctoral supervisor at Zhengzhou University, where he also serves as Vice President. He is a Changjiang Scholar Distinguished Professor, a recipient of the National Science Fund for Distinguished Young Scholars, a 「Young Top Talent」 in the Thousand Talents Program, a member of the 「Hundred, Thousand, and Ten Thousand Talents Project」, and a recipient of the China Youth Science and Technology Award. His research focuses on diamond optoelectronic materials and devices. He has published over 400 academic papers with more than 16,000 citations. His research achievements include a first-place award in the Henan Province Natural Science Awards, a second-place award in the Jilin Province Natural Science Awards, a second-place award in the Jilin Province Science and Technology Progress Awards, and a first-place award in Jilin Province's Natural Science Academic Achievements. He has led major national projects, including those funded by the National Natural Science Foundation and the Henan Provincial Joint Fund.

杨珣，郑州大学副教授。2012年本科毕业于中国科学技术大学，2017年博士毕业于中科院长春光机所。主要从事金刚石等超宽禁带半导体光电材料及器件的研究，主持国家自然科学基金面上项目、国家重点研发计划子课题、河南省科技重大专项子项目、国防重点实验室基金等项目，担任Materials和Remote Sensing杂志专刊编辑，以第一或通讯作者在Advanced Materials、Nano Letters、ACS nano、Laser & Photonics Reviews等杂志发表论文30余篇。

Yang Xun is an Associate Professor at Zhengzhou University. He graduated with a bachelor's degree from the University of Science and Technology of China in 2012 and earned his Ph.D. from the Changchun Institute of Optics, Fine Mechanics, and Physics, Chinese Academy of Sciences, in 2017. His research primarily focuses on wide-bandgap semiconductor optoelectronic materials and devices, such as diamond. He has led several projects, including those funded by the National Natural Science Foundation, the National Key Research and Development Program, major science and technology projects in Henan Province, and the National Defense Key Laboratory Fund. Yang Xun also serves as a guest editor for the journals Materials and Remote Sensing and has published over 30 papers as either the first or corresponding author in journals such as Advanced Materials, Nano Letters, ACS Nano, and Laser & Photonics Reviews.

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