Time-resolved cathodoluminescence scanning electron microscope

时间分辨阴极发光扫描电子显微镜

• 批准号: EP/R025193/1
• 负责人: Rachel Oliver
• 金额: $ 357.81万
• 依托单位: University of Cambridge
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2018
• 资助国家: 英国
• 起止时间: 2018 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FR025193%2F1
• 关键词: Time; resolved; cathodoluminescence; scanning; electron

This proposal aims to bring to the UK an amazing microscope which will provide new and powerful capability in understanding the properties of light emitting materials and devices. These materials are key to many technologies, not only technologies that utilise the light emission from materials directly (such as energy efficient light bulbs based on light emitting diodes) but also a range of other devices which utilise the same family of materials such as solar cells and electronic devices for power conversion. Some of these technologies are in current use, but their efficiency and performance can be enhanced by achieving a better understanding of the relevant materials. Other target technologies are further from the market, but may represent the building blocks of our future security and prosperity. For example, the new microscope will provide information about light sources which emit one and only one fundamental particle of light (photon) on demand. Such "quantum light sources" are a potential building block for quantum computers and for quantum cryptography schemes which represent the ultimate in secure data transfer.How will the new microscope allow us to advance the development of all these technologies? It is based on a scanning electron microscope, which utilises an electron beam incident on a sample surface to achieve resolutions almost three orders of magnitude better than can be achieved using a standard light microscope. It thus accesses the nanometre scale, which is vital to addressing modern day electronic devices. Standard electron microscopy accesses the topography of a surface, but the incoming electron beam also excites some of the electrons within the material under examination into states with a higher energy. When these electrons relax back down to their usual low energy state, light may be given out, and the colour and intensity of that light is incredibly informative about the properties of the material under examination. This light emission can be mapped on a scale of ~10 nanometres so that nanoscale structures ranging from defects to deliberately engineered quantum objects can be addressed. This technique is known as cathodoluminescence, and has been in use for many years.The new capability of our proposed system is that it will map not only the colour and intensity of the light emission, but also allow us to measure the timescales on which an electron relaxes back down to its low energy state. We use the phrase "in the blink of an eye" to describe something that happens extraordinarily quickly. A real eye blink takes at least 100 milliseconds, whereas the relevant timescales for the electron to return to its low energy state could be almost 10 billion times quicker than this! The new microscope will be able to measure processes occurring on this time scale, by addressing how long after an electron pulse excites the material a photon is emitted. It will even be able to distinguish between photons with different wavelengths (or colours) being emitted on different time scales. Crucially, coupling this time-resolved capability with the ability to vary the temperature, we will be able to infer not only the time scales on which electrons relax to low energy sites emitting a photon, but also the time scales by which electrons reduce their energy by other, non-light-emitting routes. These non-light-emitting processes are what limit the efficiency of light emitting diodes, for example. Overall, across a broad range of materials, we will build up an understanding of how electrons interact with nanoscale structure to define a material's electrical and optical properties and hence what factors limit or improve the performance of devices. The proposed system will be the most advanced in the world, and will give UK researchers working on these hugely important photonic and electronic technologies a global advantage in developing new materials, devices and ultimately products.

该提案旨在为英国带来一台令人惊叹的显微镜，它将为了解发光材料和设备的特性提供新的强大功能。这些材料是许多技术的关键，不仅是直接利用材料发光的技术（例如基于发光二极管的节能灯泡），而且是一系列利用同一系列材料的其他设备，例如太阳能电池以及用于功率转换的电子设备。其中一些技术目前正在使用，但可以通过更好地了解相关材料来提高其效率和性能。其他目标技术距离市场较远，但可能代表我们未来安全和繁荣的基石。例如，新型显微镜将根据需要提供有关发射一种且仅一种基本光粒子（光子）的光源的信息。这种“量子光源”是量子计算机和量子密码方案的潜在构建模块，代表了安全数据传输的终极目标。新显微镜将如何帮助我们推动所有这些技术的发展？它基于扫描电子显微镜，利用电子束入射到样品表面来获得比使用标准光学显微镜高出近三个数量级的分辨率。因此，它达到了纳米尺度，这对于解决现代电子设备的问题至关重要。标准电子显微镜可以观察表面的形貌，但入射的电子束也会将被检查材料内的一些电子激发到具有更高能量的状态。当这些电子松弛回到通常的低能状态时，可能会发出光，并且光的颜色和强度对于所检查材料的特性提供了令人难以置信的信息。这种光发射可以在约 10 纳米的尺度上进行绘制，从而可以解决从缺陷到故意设计的量子物体的纳米级结构。这种技术被称为阴极发光，已经使用了很多年。我们提出的系统的新功能是，它不仅可以绘制光发射的颜色和强度，还可以让我们测量光发射的时间尺度。电子弛豫回到低能态。我们用“眨眼间”这个短语来描述发生得非常快的事情。真正的眨眼至少需要 100 毫秒，而电子返回低能状态的相关时间尺度可能比这快近 100 亿倍！新的显微镜将能够通过确定电子脉冲激发材料后多长时间发射光子来测量在这个时间尺度上发生的过程。它甚至能够区分在不同时间尺度上发射的不同波长（或颜色）的光子。至关重要的是，将这种时间分辨能力与改变温度的能力结合起来，我们不仅能够推断出电子弛豫到发射光子的低能量位点的时间尺度，还能够推断出电子减少能量的时间尺度通过其他非发光路线。例如，这些非发光工艺限制了发光二极管的效率。总的来说，在广泛的材料中，我们将了解电子如何与纳米级结构相互作用，以定义材料的电学和光学特性，从而确定哪些因素限制或提高设备的性能。拟议的系统将是世界上最先进的，并将为研究这些极其重要的光子和电子技术的英国研究人员提供开发新材料、设备和最终产品的全球优势。

项目成果

Radiation effects in ultra-thin GaAs solar cells

• DOI: 10.1063/5.0103381
• 发表时间: 2022-11-14
• 期刊: JOURNAL OF APPLIED PHYSICS
• 影响因子: 3.2
• 作者: Barthel, A.;Sayre, L.;Hirst, L. C.
• 通讯作者: Hirst, L. C.

Cathodoluminescence Study of 68 MeV Proton-Irradiated Ultra-Thin GaAs Solar Cells

68 MeV 质子辐照超薄砷化镓太阳能电池的阴极发光研究

• DOI: 10.1109/pvsc45281.2020.9300748
• 发表时间: 2020
• 作者: Barthel A

Combined SEM-CL and STEM investigation of green InGaN quantum wells

• DOI: 10.1088/1361-6463/abddf8
• 发表时间: 2021-04-22
• 期刊: JOURNAL OF PHYSICS D-APPLIED PHYSICS
• 影响因子: 3.4
• 作者: Ding, B.;Jarman, J.;Oliver, R. A.
• 通讯作者: Oliver, R. A.

Stacking fault-associated polarized surface-emitted photoluminescence from zincblende InGaN/GaN quantum wells

• DOI: 10.1063/5.0012131
• 发表时间: 2020-07-20
• 期刊: APPLIED PHYSICS LETTERS
• 影响因子: 4
• 作者: Church, S. A.;Ding, B.;Binks, D. J.
• 通讯作者: Binks, D. J.

Halide Homogenization for High-Performance Blue Perovskite Electroluminescence.

用于高性能蓝色钙钛矿电致发光的卤化物均质化

• DOI: 10.34133/2020/9017871
• 发表时间: 2020
• 期刊: Research (Washington, D.C.)
• 作者: Cheng L;Yi C;Tong Y;Zhu L;Kusch G;Wang X;Wang X;Jiang T;Zhang H;Zhang J;Xue C;Chen H;Xu W;Liu D;Oliver RA;Friend RH;Zhang L;Wang N;Huang W;Wang J
• 通讯作者: Wang J