High-speed photodiodes for 2.0-4.0 μm spectral range

This paper reviews some recent developments in the high-speed photodiodes for 2.0-4.0 im spectral range. We report investigation, design and fabrication of broad bandwidth (2 GHz) GaInAsSb/GaA1AsSb p-i-n photodiodes operating in the 0.9-2.4 μm spectral range with submicroampere dark cunent. As well, we present InAs-based and InAs/InAsSbP photodiodes with long-wavelength cutoff of 3.8 μm. An analysis of the photodiode performance through the investigation of current-voltage, capacitance-voltage and spectral responsivity characteristics was carried out. Also, noise and speed-response characteristics were studied. In addition to high-speed response and low noise level these photodiodes offer room-temperature operation and hence are commercially viable. These devices are of great interest for a wide range of applications, such as high-resolution laser diode spectroscopy of gases and molecules, eye-safe laser rangefinding systems, the free-space optical link as well as systems of optical fiber communication.