Resonant-Cavity Photodetectors

9629636坎贝尔本研究计划的目标将是双重的： 1)建立在雪崩光电二极管（APD）光电探测器以前的工作，以开发一个现实的模型，可以用作一种工具，以促进器件的设计和优化，并进行系统的实验研究的关键结构参数，包括带边不连续性，势垒和阱区的宽度，和组成的势垒层的轮廓。模拟和实验工作之间的紧密耦合是该计划的优势，并将为理解和开发这些技术上重要的光电探测器提供必要的反馈。 2)这也是本研究提出的目标，实现新的光电探测器，利用新颖的resonantcavity结构，以实现增强的性能相对于传统的光电探测器。 实现这些新型光电探测器的一个关键方面是对决定其性能的物理效应的基本理解。例如，谐振腔方法已经成功地扩展到雪崩光电二极管。然而，在这种类型的结构中，撞击电离过程的某些方面还没有很好地理解。 谐振腔结构可以提供若干性能优点，其中之一是可以避免传统PIN光电二极管结构固有的响应度/带宽之间的权衡。 对于典型的垂直入射光电探测器，宽的带宽需要薄的吸收层，这反过来又导致低的量子效率。另一方面，谐振腔结构有效地提高了带宽的渡越时间分量的响应度，因为光信号多次穿过微腔内的薄吸收层。例如，Si基谐振腔光电二极管已经证明，可以在不牺牲量子效率的情况下实现带宽的10倍增加。此外，这些光电探测器的窄光谱响应可用于诸如波分复用的应用。例如，高Q腔可以提供集成滤波功能。 ***

9629636 Campbell The objectives of this research program will be two fold: 1) to build on previous work in the avalanche photodiodes (APD) photodetectors to develop a realistic model that can be used as a tool to facilitate device design and optimization and to conduct a systematic experimental study of the critical structural parameters, including the bandedge discontinuities, the widths of the barrier and well regions, and the composition profile of the barrier layers. Tight coupling between the simulation and experimental work is a strength of this program and will provide the feedback necessary for understanding and developing these technologically important photodetectors. 2) It is also the objective of this proposed research to realize new photodetectors that utilize novel resonantcavity structures to achieve enhanced performance relative to conventional photodetectors. A crucial aspect to achieving these novel photodetectors is a fundamental understanding of the physical effects that determine their performance. For example, the resonantcavity approach has been successfully extended to avalanche photodiodes. However, there are aspects to the impact ionization process in this type of structure that are not well understood. The resonant-cavity structure can provide several performance advantages, one of which is that the tradeoff between responsivity/bandwidth that is inherent to conventional PIN photodiodes structures can be circumvented. For the typical normal-incidence photodetector, a wide bandwidth necessitates a thin absorption layer which, in turn, results in low quantum efficiency. The resonant-cavity structure, on the other hand, effectively decouples the responsivity from the transit-time component of the bandwidth because the optical signal makes multiple passes across the thin absorbing layer inside the microcavity. For example, it has been demonstrated with Si-based resonant-cavity photodiodes that a 10x increase in bandwidth can be achieve without sacrificing quantum efficiency. In addition, the narrow spectral response of these photodetectors may be used to advantage for applications such as wavelength-division multiplexing. For example, high Q cavities can provide an integrated filtering function. ***