Amorphous and Nanocrystalline Semiconductors for Optoelectronic Applications: Photoconductors, Detectors and Sensors Based on a-Se Alloys and Optoelectronic Glasses

用于光电应用的非晶和纳米晶半导体：基于a-Se合金和光电玻璃的光电导体、探测器和传感器

• 批准号: RGPIN-2016-04982
• 负责人: Kasap, Safa
• 金额: $ 3.93万
• 依托单位: University of Saskatchewan
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2019
• 资助国家: 加拿大
• 起止时间: 2019-01-01 至 2020-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=690434
• 关键词: Amorphous; Nanocrystalline; Semiconductors; Optoelectronic; Applications

The DG program on optoelectronic materials for radiation detection and imaging includes a major study on doped amorphous Se-As alloys (a-Se:As) and a complimentary study on rare-earth doped glasses and glass ceramics (containing nanocrystals). a-Se alloys have one clear distinct advantage over crystalline semiconductors that they can be conveniently fabricated over large areas, which has led to their extensive commercial use in flat panel x-ray image detectors. The long term objective is to build on strength by extending our scientific and technological knowledge on doped a-Se alloy based semiconductors and devices by discoveries at the material and device levels; and advancing knowledge at the fundamental level. The design of next generation a-Se detectors, in particular for use in general radiology, CT and tomosynthesis, also needs extensive knowledge of the electrical properties of the photoconductor used in the three layers, e.g. drift mobilities, carrier trapping and recombination lifetimes, sensitivity, dark current, excess noise, thermal generation rate, x-ray induced effects (such as defect creation or damage) and relaxation effects - these alloys are glasses that age and exhibit relaxation effects. Given the availability of the Canadian Light Source (CLS), we intend to continue to use of the synchrotron facility in our research and continue to collaborate with the CLS staff; and also continue with our industrial partner in relating results to practical detectors. The research program will encompass all aspects of photoconductor research from present to new a-Se alloys (doped) in a concerted effort to relate detector performance to fundamental semiconductor properties through physical models. It will also include Sm3+ doped glasses and glass ceramics for Microbeam Radiation Therapy in which we need to accurately measure the dose profile in the microbeam at the CLS BMIT line (peak dose 2 - 3 kGy with a width 20 um). There will be a number of projects within this DG program. Typical examples: (a) Study of optoelectronic properties of new doped a-Se alloys as a function of temperature and electric field toward enhanced p-i-n structures (thicker i-layer) with lower dark currents and higher applied fields. (b) Study of the x-ray energy dependence of photoconductivity of a-Se alloys, MTF, DQE as a function of operating field, temperature, total dose and dose rate. (d) Study of the effects of x-ray irradiation on the photoconductor properties and hence on the sensitivity and DQE of the actual detector. (e) Discovering new Sm-doped optoelectronic glasses (OEGs) that are tissue equivalent for better MRT dose distribution monitoring and addressing current problems (energy dependence). The impact of the work is the generation of new knowledge on doped a-Se alloys with new compositions for the design and development of next generation flat panel x-ray detectors and new OEGs for high-dose dosimetry.

用于辐射探测和成像的光电材料的 DG 计划包括对掺杂非晶 Se-As 合金 (a-Se:As) 的主要研究以及对稀土掺杂玻璃和玻璃陶瓷（含有纳米晶体）的补充研究。与晶体半导体相比，a-Se 合金有一个明显的优势，即它们可以方便地大面积制造，这导致它们在平板 X 射线图像探测器中得到广泛的商业应用。长期目标是通过材料和器件层面的发现，扩展我们在掺杂 a-Se 合金半导体和器件方面的科技知识，从而增强实力；并在基础层面上推进知识。下一代 a-Se 探测器的设计，特别是用于普通放射学、CT 和断层合成的探测器，还需要对三层中使用的光电导体的电特性有广泛的了解，例如漂移迁移率、载流子捕获和复合寿命、灵敏度、暗电流、过量噪声、热生成速率、X 射线诱导效应（例如缺陷产生或损坏）和弛豫效应 - 这些合金是会老化并表现出弛豫效应的玻璃。鉴于加拿大光源（CLS）的可用性，我们打算在我们的研究中继续使用同步加速器设施，并继续与 CLS 工作人员合作；并继续与我们的工业合作伙伴将结果与实际探测器联系起来。该研究计划将涵盖光电导体研究的各个方面，从现有的到新型 a-Se 合金（掺杂），共同努力通过物理模型将探测器性能与基本半导体特性联系起来。它还将包括用于微束放射治疗的 Sm3+ 掺杂玻璃和玻璃陶瓷，其中我们需要精确测量 CLS BMIT 线微束中的剂量分布（峰值剂量 2 - 3 kGy，宽度 20 um）。该总干事计划内将包含许多项目。典型示例： (a) 研究新型掺杂 a-Se 合金的光电特性随温度和电场的变化，以实现具有更低暗电流和更高施加场的增强 p-i-n 结构（更厚的 i 层）。 (b) 研究 a-Se 合金光电导率、MTF、DQE 的 X 射线能量依赖性，作为工作场、温度、总剂量和剂量率的函数。 (d) 研究 X 射线照射对光电导体特性的影响，从而对实际探测器的灵敏度和 DQE 的影响。 (e) 发现新的组织等效的 Sm 掺杂光电玻璃 (OEG)，以更好地监测 MRT 剂量分布并解决当前问题（能量依赖性）。这项工作的影响是产生了关于掺杂 a-Se 合金的新知识，该合金具有新的成分，用于设计和开发下一代平板 X 射线探测器和用于高剂量剂量测定的新型 OEG。