DETECTION OF TERAHERTZ RADIATION BY HOT-ELECTRON EFFECTS IN COUPLED-QUANTUM-WELL PHOTODIODES

Detection of continuous-wave terahertz (THz) radiation has been demons trated in GaAs/AlGaAs coupled quantum well p-i-n photodiodes by intras ubband absorption. The sharp interwell tunneling resonances observed i n the photocurrent are highly sensitive to temperature, and the carrie r temperature increase caused by the absorption of THz radiation is fo und to affect the photocurrent in a qualitatively similar manner. We f ind that the effect results in detectivities of THz radiation around 1 mA/W for a photocurrent signal of 100 nA. We discuss the functionalit y of our device in the context of an ''optical/THz mixer,'' where the mixing occurs between the modulation frequencies of the applied THz an d visible light fields. (C) 1996 American Institute of Physics.