Photodetector is one of key component in optoelectronic integrated circuits (OEICs). Photodetectors are extensively used in optical communication systems, optical interconnections, and biomedical imaging, and they typically operate from visible to near-infrared wavelength. For most applications, one or more of the following performance characteristics including high-sensitivity or quantum efficiency, high-speed, low noise, high dynamic range may be required. However, in optimizing the design of photodetectors, there is a key performance trade-off between quantum efficiency or sensitivity, and speed. To overcome this trade-off and simultaneously obtain high speed and high sensitivity, resonant cavity enhanced photodetectors (RCE-PDs) are used. Here, we discuss, in detail, various RCE-PD structures with an emphasis on theory, design, modeling and performance characteristics. Important research results are summarized and ideas on how to improve the design of RCE-PDs are presented. The time and frequency response, important for high-speed or high bit rate applications, are discussed from the perspective of detectors in real applications. For optimized design of OEICs, circuit models are indispensable. Therefore, we discuss circuit models for RCE-PDs, including the effects of parasitic elements on time response characteristics as well as device design optimization. The various materials combinations that have been used for RCE-PDs as well as different types of photodetectors are summarized. Finally, the rapidly emerging, high-performance RCE quantum dot photodetectors for mid-infrared applications are introduced.