Terahertz Quantum Well Photodetectors

The terahertz (THz) part of the electromagnetic spectrum promises a wide range of new and novel, some may be disruptive, applications. However, the development of technologies in the THz spectrum or the very far infrared region has been slow mainly because of the lack of convenient detectors and lasers. There are a few competing new approaches for better detectors, and here, we concentrate on one based on quantum wells. We report on the design and simulated performance of quantum-well photodetectors for the terahertz (1-10 THz). Quantum well, barrier, and doping parameters are optimized in terms of operating temperature, absorption, and detectivity. We also report on our experimental demonstration of GaAs/AlGaAs photodetectors with background limited infrared performance. These devices are suited for a variety of applications, especially in conjunction with the newly developed THz quantum cascade lasers. Examples include THz sensing and imaging and free space communication.