项目针对日盲紫外AlGaN光电阴极的单光子级微弱信号探测能力提升，提出利用极化增强效应和变组分内建电场进行复合结构优化设计，并针对复合结构阴极材料开展化学清洗、热清洗及Cs-O-Cs激活等制备工艺的优化，提升阴极表面的Cs-O吸附性能和激活性能，以及阴极真空衰减后的二次激活后的表面势垒重构性能，最终提升阴极的光电发射性能和单光子微弱信号探测能力。利用阴极材料激活前的瞬态浓度光栅、稳态光电压谱测试和激活后的光谱响应测试构建复合结构阴极材料的闭环评价体系，并结合第一性理论仿真、压电极化理论、二维空穴基态波函数、光生载流子输运理论和定态薛定谔方程对阴极材料的光电发射机理和光谱响应调制进行系统研究。项目研究成果为臭氧探测、空间探测、高能物理、导弹预警、紫外通信、生化分析等领域单光子微弱信号探测所需的日盲紫外探测AlGaN光电阴极制备提供系统理论指导和复合评价手段。

Aiming at improving the weak signal and single photon detection ability of solar-blind ultraviolet AlGaN photocathode, the project puts forward using effect of polarization enhancement and built-in field support with variable components to conduct the composite structure optimization design, and carries out the optimization of preparing technology, such as chemical cleaning, heat cleaning, Cs-O-Cs activation for composite structure cathode materials, and then improve the surface Cs-O adsorption and activation performance of cathodes, as well as the surface barrier reconstruction properties of secondary activated cathodes after vacuum attenuation, and ultimately improve the cathode photoemission performance, weak signal and single photon detection capabilities. Using instantaneous concentration grating, steady photovoltage spectroscopy test before activation and spectral response measurement after activation for cathode material, we build a closed-loop evaluation system for cathode material with composite structure, and using first-principle theory simulation, piezoelectric polarization theory, two-dimensional electron hole ground state wave function, photo-generated carrier transport theory and stationary Schrodinger equation to construct the corresponding evaluation theory for photoelectric emission mechanism and spectral response modulation of cathode materials. Research achievements of the project will provide effective theoretical guidance and evaluation methods for the preparation of solar blind ultraviolet AlGaN photocahtode used as weak signal and single photon detection in the detection ozone, space exploration, high energy physics, missile warning, ultraviolet communication, biochemical analysis and other fields.