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惊人的显微镜，该显微镜将为理解发光材料和设备的特性提供新的强大能力。这些材料是许多技术的关键，不仅可以直接利用材料发射光发射（例如基于发光二极管的能源有效的灯泡），而且还利用了许多其他设备，这些设备都利用了相同的材料家族（例如太阳能电池家族和电子设备）进行电源转换。这些技术中的一些是目前使用的，但是通过更好地了解相关材料，可以提高其效率和性能。其他目标技术离市场更远，但可能代表了我们未来的安全和繁荣的基础。例如，新的显微镜将提供有关光源的信息，这些光源可按需发射一个和仅发光的一个基本粒子（光子）。这样的“量子光源”是量子计算机的潜在构件和代表安全数据传输最终的量子加密方案。新的显微镜将如何允许我们推动所有这些技术的开发？它是基于扫描电子显微镜，该扫描电子显微镜利用出现在样品表面上的电子束以比使用标准光显微镜要实现的分辨率要好几乎三个数量级。因此，它可以访问纳米量表，这对于解决现代电子设备至关重要。标准电子显微镜可以访问表面的地形，但是传入的电子束也激发了所检查的材料中的某些电子，以较高的能量进行。当这些电子放松到通常的低能状态时，可能会发出光，并且该光的颜色和强度对正在检查的材料的特性非常有用。可以将这种光发射映射到约10纳米的尺度上，以便可以解决从缺陷到故意设计的量子对象的纳米级结构。该技术被称为阴极发光，已经使用了多年了。我们提出的系统的新能力不仅会绘制光发射的颜色和强度，而且还使我们能够测量电子在其上放松到其低能状态的时间表。我们使用“眨眼”一词来描述很快发生的事情。真正的眼睛眨眼至少需要100毫秒，而电子返回其低能状态的相关时间尺度可能比此更快地比这快了100亿倍！新的显微镜将能够通过解决电子脉冲激发光子发射的材料后的时间来测量在此时间尺度上发生的过程。它甚至能够区分不同时间尺度上发出不同波长（或颜色）的光子。至关重要的是，将这种时间分辨的能力与变化温度变化的能力结合在一起，我们将不仅能够推断电子放松到低能位点的时间尺度，还可以推断出发光光子的低能位点，还可以推断出电子通过其他非光线发射路线来减少其能量的时间尺度。例如，这些非光发射过程限制了发光二极管的效率。总体而言，在广泛的材料中，我们将建立对电子如何与纳米级结构相互作用的理解，以定义材料的电气和光学特性，从而限制或改善设备的性能。拟议的系统将是世界上最先进的系统，并将使英国研究人员在开发新材料，设备和最终产品方面具有全球优势。

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