Design, Fabrication, and Characterizations of Novel Multispectral Photodetectors Using Postgrowth Fabry–Perot Optical Filters for Simultaneous Near Infrared/Short-Wave Infrared Detection

A novel InP-based multispectral photodetector chip, using multiple Fabry-Perot resonant cavities integrated with photodectors, was designed, fabricated, and characterized. The integrated devices are capable of simultaneous wavelength detection at four wavelengths in the near infrared/short-wave infrared regime such as 1.32, 1.41, 1.49, and 1.66 μm. Experimental results show highly distinguishable detection peaks from 22.8% to 37.4%. A little change in dark current density has been observed after filter integration (~2χ10^-2 A/cm² at -10 V). The experimental full-width half-maximum values are 2.18-2.9 times of the design´s, indicating light scattering caused by cavity etch and cavity thickness nonuniformities. The discrepancy between design and experimental results are analyzed for a better understanding of the filter properties and experimental variables.