Abstract
Sensitive high speed photodiode detectors have been prepared in various compositions of (Hg,Cd)Te for the 1-μ to 3-μ spectral region. These detectors, operating at room temperature, exhibit quantum efficiencies in the 40–70% range and specific detectivities that range from at 1.3 μ to at 3 μ. Improved performance is possible by cooling the photodiode detector; specific detectivities of approaching the BLIP limit at 2.2 μ have been measured at 77 K. Response time measurements using detector–preamplifier modules have been made with 0.9 μ, 1.06 μ and 1.54-μ pulsed radiation. The response time of approximately 10 nsec does not appear wavelength-dependent and is limited by the RC product and amplifier bandwidth. When the photodiode is terminated with a very broadband amplifier, the pulse response is limited by the RC product to 0.5 nsec and a secondary time constant of ~5 nsec is observed that is believed to be caused by the transit time of stored charge carriers.
© 1972 Optical Society of America
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