基于亚波长光栅聚焦透镜的硅基集成单行载流子光探测器

Uni-traveling carrier photodetectors (UTC-PDs), which use only electrons as carriers traveling through the pn junctions, can depress the space charge effect efficiently, and thus own excellent performance of high response speed and high saturation output power. Conventional UTC-PDs based on InP material system are with low external quantum efficiency due to the thin and small active absorption regions. And also, it is very difficult for them to be integrated with silicon-based photoelectric functional devices. It is very significant to develop UTC-PDs with high quantum efficiency, high speed, and compatible with CMOS process technology platform. As novel micro-nano structures, subwavelength gratings are attracting tremendous interest owing to their promising applications in high performance semiconductor optoelectronic devices. When the micro-nano structures on the subwavelength gratings arrange in a special way, especially in a way of non-periodicity or non-uniformity, a series of particular but controllable modulation phenomena of the gratings on the incident light fields will appear. This project investigates on the fundamental physical mechanism and the basic law of transmission and focusing properties of subwavelength gratings at micro-nano scale. We expect that, with the help of the particular modulation effects of subwavelength gratings and the feasible integration technique between heterogeneous semiconductor materials, novel UTC-PDs, which are with high quantum efficiency, high response speed，and compatible with silicon-based photonic and electronic devices, will come true in the near future.

单行载流子光探测器（UTC-PD）仅以电子作为传输载流子流过器件pn结区，可以很好地抑制空间电荷屏蔽效应，因而拥有优异的饱和输出和高速响应性能。传统UTC-PD基于InP材料系，有源吸收区较薄，面积较小，因而外部量子效率较低，且不易与硅基光电功能器件集成。研制高效、高速、与CMOS工艺技术平台兼容的新型UTC-PD具有重要意义。亚波长光栅作为一种新型微纳结构，在半导体光电子器件中的应用研究已得到广泛关注。当亚波长光栅上的微纳结构图形按特定规律，特别是呈非周期、非均匀方式排列时，会对入射光场产生一系列特殊、可控的调制现象。本项目重点研究微纳尺度亚波长光栅实现透射、聚焦等光场调制特性的物理机理和基本规律，希望借助具有特定微纳结构的亚波长光栅对入射光场的特殊调制功能，以及切实可行的半导体异质材料集成工艺，实现高量子效率、高响应速度、易于与硅基光子或电子器件集成的新型UTC-PD。

亚波长光栅在新型集成半导体光电子器件中的应用已得到广泛关注。由于结构上的紧凑性，亚波长光栅结构器件在与其它半导体器件集成时有着潜在优势。继续探究新型亚波长光栅与光场相互作用的物理机理，不断揭示两者因相互作用而出现的新的光学现象、光谱规律，有利于进一步拓展亚波长光栅在集成光电子器件中的应用。借助角分辨光谱测试系统，项目深入研究并揭示了一维亚波长光栅在特定的光场入射方式下，所呈现出的一系列新的光谱特性：当光场入射面平行于光栅走向时，其所有导模共振光谱均呈现简并特性，且不同的共振光谱随入射角的变化而变化的基本规律存在显著不同，深入研究相关光谱变化规律，对于研发超高品质因子光栅滤波器等新型半导体器件具有现实意义；光场入射面既不平行也不垂直于光栅走向（介于两者之间）时，以特定方法优化光栅结构参数，可实现一维亚波长光栅的偏振不敏感特性。此外，项目研究了一种沉积于特殊微坑结构中的多层介质膜器件，深入分析了该器件与入射光场作用后所呈现的若干独特光谱现象。项目取得的成果对于丰富亚波长光栅的功能、应用，促进其与光电探测器等其它半导体器件的集成具有一定价值。