Photo-detection in a reverse biased InGaAs/InP laser structure at 1.5μm

The authors have demonstrated that a conventional multiple quantum well ridge waveguide laser can also be operated as a high-speed photodetector with an internal quantum efficiency = 100% at a reverse bias of 5 V. The speed of this detector is limited by the escape of photo-generated carriers from the InGaAsP barriers to the InP cladding layer. The processes controlling the time response of the detector are considered. The photo-generated carriers must escape from the quantum well, diffuse across the InGaAsP barrier regions to the interface with the doped InP contacts and then escape over this barrier. The carrier escape mechanism is therefore a combination of thermionic emission, phonon-assisted tunneling and direct tunneling from the quantum well region. The carrier escape time is limited by the slowest of these processes