High Performance Ultrafast Photodetectors.
Annual rept. Jun-Oct 96,
BOSTON UNIV MA
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We report spectral and high-speed measurement results on resonant cavity enhanced RCE Schottky photodiodes. The Schottky metal contact is semi-transparent and provides the top mirror reflectivity. We demonstrated by simulations that the detector responsivity can be optimized by using a dielectric coating on top of the metal contact. The novel concept of combining a dielectric impedance matching layer with the semi-transparent metal mirror drastically improves the expected quantum efficiency of RCE Schottky photodiodes. Simulations in GaAsInGaAs material system predicted more than 70 quantum efficiency for an absorbing region of O.13um. The devices were fabricated by using a microwave compatible process. On-wafer high-speed measurements yielded a 18 Ps pulse width corresponding to a 3-dB bandwidth of 20 GHz. We also report on our efforts on polarization sensing photodetectors.
- Optical Detection and Detectors