Ultrafast quantum well infrared photo detector

Quantum well infrared photo-detectors (QWIP) have found numerous application as sensitive fast photo-detectors. Applications for fast detectors include laser diagnostics, telecommunications and Compton scattering measure- ments. The high speed potential of QWIPs is enabled by a short carrier lifetime in the order of 5 pS. This short lifetime permits design of a 40 GHz bandwidth detector. In this paper we report on the development of a QWIP with an integrated electrical co-planar waveguide. The QWIP is a 100 well structure that is almost completely absorbing over the wavelength range of 9 to 11 microns. The QWIP was fabricated with a gold air bridge to connect the top of the mesa to the center line of a gold co-planar waveguide. The co-planar waveguide is tapered to allow direct connection to 2.4 mm and smaller electrical cable. Initial tests indicate that the device has a 40 GHz or greater bandwidth.