{"title":"Optimized substrate temperature for high-quality CdZnTe epitaxial film in X-ray flat panel detectors","authors":"","doi":"10.1016/j.vacuum.2024.113705","DOIUrl":null,"url":null,"abstract":"<div><div>Cadmium zinc telluride (CdZnTe or CZT) materials, favored for their physical superiority in optoelectronic applications, can be efficiently produced as large-area epitaxial film via close space sublimation (CSS), enhancing potential in flat-panel detector imaging. However, the application of CdZnTe epitaxial film in medical imaging equipment is limited by their lower resistivity, prolonged response times, and diminished sensitivity. By elevating the substrate temperature, we enhanced the number and depth of reverse sublimation pits on the surface of the CdZnTe epitaxial film, established an approximately 100 nm Zn-rich layer, broadened the bandwidth, and minimized electrode injection. Additionally, we observed an aggregation of dislocations at the edges of the reverse sublimation pits, which promoted surface recombination and reduced leakage current. These modifications significantly increased the film's resistivity to 10<sup>11</sup> Ω cm. Further, they notably decreased the rise and drop times to 2 m s and 4 m s, respectively. Integrated with thin-film transistors (TFTs), the optimized CdZnTe epitaxial film now distinctly differentiate between air, plastics, and metals under X-ray examination. This improved performance of X-ray flat panel detectors (FPDs) based on CdZnTe epitaxial film is promising for the development of next-generation X-ray detection systems.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":null,"pages":null},"PeriodicalIF":3.8000,"publicationDate":"2024-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Vacuum","FirstCategoryId":"88","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0042207X24007516","RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"MATERIALS SCIENCE, MULTIDISCIPLINARY","Score":null,"Total":0}
引用次数: 0
Abstract
Cadmium zinc telluride (CdZnTe or CZT) materials, favored for their physical superiority in optoelectronic applications, can be efficiently produced as large-area epitaxial film via close space sublimation (CSS), enhancing potential in flat-panel detector imaging. However, the application of CdZnTe epitaxial film in medical imaging equipment is limited by their lower resistivity, prolonged response times, and diminished sensitivity. By elevating the substrate temperature, we enhanced the number and depth of reverse sublimation pits on the surface of the CdZnTe epitaxial film, established an approximately 100 nm Zn-rich layer, broadened the bandwidth, and minimized electrode injection. Additionally, we observed an aggregation of dislocations at the edges of the reverse sublimation pits, which promoted surface recombination and reduced leakage current. These modifications significantly increased the film's resistivity to 1011 Ω cm. Further, they notably decreased the rise and drop times to 2 m s and 4 m s, respectively. Integrated with thin-film transistors (TFTs), the optimized CdZnTe epitaxial film now distinctly differentiate between air, plastics, and metals under X-ray examination. This improved performance of X-ray flat panel detectors (FPDs) based on CdZnTe epitaxial film is promising for the development of next-generation X-ray detection systems.
碲化镉锌(CdZnTe 或 CZT)材料因其在光电应用中的物理优越性而备受青睐,可通过近空间升华(CSS)技术高效生产大面积外延薄膜,从而提高平板探测器成像的潜力。然而,由于 CdZnTe 外延薄膜电阻率较低、响应时间较长、灵敏度较低,其在医疗成像设备中的应用受到了限制。通过提高衬底温度,我们增加了 CdZnTe 外延薄膜表面反向升华凹坑的数量和深度,形成了约 100 nm 的富锌层,拓宽了带宽,并最大限度地减少了电极注入。此外,我们还观察到反向升华凹坑边缘的位错聚集,这促进了表面重组并降低了漏电流。这些改性使薄膜的电阻率大幅提高到 1011 Ω cm。此外,它们还将上升和下降时间分别显著缩短至 2 m s 和 4 m s。与薄膜晶体管(TFT)集成后,经过优化的碲化镉外延薄膜现在可以在 X 射线检测下明显区分空气、塑料和金属。基于 CdZnTe 外延薄膜的 X 射线平板探测器(FPD)性能的提高为下一代 X 射线探测系统的开发带来了希望。
期刊介绍:
Vacuum is an international rapid publications journal with a focus on short communication. All papers are peer-reviewed, with the review process for short communication geared towards very fast turnaround times. The journal also published full research papers, thematic issues and selected papers from leading conferences.
A report in Vacuum should represent a major advance in an area that involves a controlled environment at pressures of one atmosphere or below.
The scope of the journal includes:
1. Vacuum; original developments in vacuum pumping and instrumentation, vacuum measurement, vacuum gas dynamics, gas-surface interactions, surface treatment for UHV applications and low outgassing, vacuum melting, sintering, and vacuum metrology. Technology and solutions for large-scale facilities (e.g., particle accelerators and fusion devices). New instrumentation ( e.g., detectors and electron microscopes).
2. Plasma science; advances in PVD, CVD, plasma-assisted CVD, ion sources, deposition processes and analysis.
3. Surface science; surface engineering, surface chemistry, surface analysis, crystal growth, ion-surface interactions and etching, nanometer-scale processing, surface modification.
4. Materials science; novel functional or structural materials. Metals, ceramics, and polymers. Experiments, simulations, and modelling for understanding structure-property relationships. Thin films and coatings. Nanostructures and ion implantation.