Amorphous semiconductors for optoelectronic applications: photoconductors, detectors and sensors based on se-alloys

非晶态半导体，如氢化非晶硅(a-Si：H)及其合金、非晶态硒(a-Se)及其合金(a-Se：As)等，与晶态半导体相比有一个明显的优势，即可以方便地大面积制造，这使得它们在光伏、平板显示器(TFT显示器)、平板X射线图像探测器和柔性电子设备中得到了广泛的商业应用。在电子和光电设备领域，非晶态半导体代表着一个特别重要的利基市场，加拿大在这一领域具有非常强大的竞争力。我们的长期目标和目标是通过材料层面的创新、器件层面的创新和基础层面的知识进步，通过扩大我们在a-Se合金半导体和光电子器件方面的科学技术知识来增强实力。下一代a-Se X射线图像探测器的设计还需要对这三层中使用的光电导体的电学性质有广泛的了解，例如，载流子范围、漂移迁移率x载流子寿命、过剩噪声和每一层中的热产生速率。到目前为止，还没有人研究a-se p-i-n探测器中电子噪声的性质，我们打算将此作为一项主要研究。我们的目标和研究将包括：(I)发现和了解a-Se：As合金的电学和光电性质随温度和电场的变化，从而获得具有较低暗电流和较高外场的增强p-i-n结构；增加电场将改善DQE。(2)发现低频(1/f)噪声的行为，以便更好地设计探测器。(Iii)通过从(I)中增强材料性能，使i层和p层的组合物更稳定。(4)发展具有倍增功能的雪崩a-Se结构，证明它们适合用于超灵敏光学成像和间接辐射探测。当然，这项工作的影响是产生了关于a-Se探测器的新知识，具有新组合物的新结构，用于设计和开发下一代a-Se x射线探测器，以及全固态超声光学图像传感器。

Amorphous semiconductors, such as hydrogenated amorphous silicon (a-Si:H) and its alloys, amorphous selenium (a-Se) and its alloys (a-Se:As) etc, have one clear distinct advantage over crystalline semiconductors that they can be conveniently fabricated over large areas, which has lead to their extensive commercial use in photovoltaics, flat panel displays (TFT displays), flat panel x-ray image detectors, and flexible electronics. Within the field of electronic and optoelectronic devices, amorphous semiconductors represent a particularly important niche in which Canada has a very strong and competitive presence. Our long term goals and objectives are to build on strength by expanding our scientific and technological knowledge on a-Se alloy based semiconductors and optoelectronic devices by innovation at the material level, innovation at the device level and advancing knowledge at the fundamental level. The design of next generation a-Se x-ray image detectors also needs extensive knowledge on the electrical properties of the photoconductor used in the three layers, e.g. charge carrier ranges, drift mobility x carrier lifetime, excess noise and thermal generation rate in each layer. To date, no one has examined the nature of electronic noise in a-Se p-i-n detectors and we intend to take this on as a major study. Our objectives and studies will include: (i) Discovering and understanding the electrical and optoelectronic properties of a-Se:As alloys as a function of temperature and electric field toward enhanced p-i-n structures with lower dark currents and higher applied fields; increasing the field will improve the DQE. (ii) Discovering the behavior of low-frequency (1/f) noise for better detector design. (iii) More stable compositions for the i-layer and p-layer through enhanced material properties from (i). (iv) Developing avalanche a-Se structures with multiplication, demonstrating their suitability for use in ultrasensitive optical imaging and in indirect radiation detection. The impact of the work is, of course, the generation of new knowledge on a-Se detectors, novel structures with new compositions, for the design and development of next generation a-Se x-ray detectors, and all solid state ultrasenstive optical image sensors.