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22 December 1997 Ultrafast resonant-cavity-enhanced Schottky photodiodes
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Resonant cavity enhanced (RCE) photodiodes are promising candidates for applications in optical communications and interconnects where ultrafast high-efficiency detection is very desirable. In RCE structures, the electrical function of the photodiode is largely unchanged, but optically it is subject to the effects of the cavity, mainly wavelength selectivity and a large enhancement of the resonant optical field. The increased optical field allows photodetectors to be made thinner and therefor faster in the transit-time limited operation, while simultaneously maintaining a high quantum efficiency at the resonant wavelengths. The combination of RCE detection scheme with Schottky photodiodes allows for fabrication of high-performance photodetectors with relatively simple material structure and fabrication process. In RCE Schottky photodiodes, a semi-transparent metalization can be used simultaneously as the electrical contact and the top reflector for the resonant cavity. Device performance is optimized by varying the thickness of the Schottky metalization and utilizing a dielectric matching layer. We present theoretical and experimental results on spectral and high-speed properties. We have demonstrated RCE Schottky photodiodes in (Al, In)GaAs/GaAs material system with temporal response of 10 ps full-width-at-half-maximum. These results were measurement setup limited and a conservative estimation of the bandwidth corresponds to more than 100 GHz. The photodiodes were designed and fabricated for 900 nm and 840 nm resonant wavelengths. The best measured quantum efficiency is around 50% which is slightly less than the theoretical prediction for these devices.
© (1997) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
M. Selim Unlu, Bora M. Onat, Mutlu Goekkavas, Ekmel Ozbay, Erhan P. Ata, Elias Towe, Gary Tuttle, Richard P. Mirin, and David H. Christensen "Ultrafast resonant-cavity-enhanced Schottky photodiodes", Proc. SPIE 3290, Optoelectronic Integrated Circuits II, (22 December 1997);

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