Detection of Intersubband Transitions in Gallium Arsenide Coupled Quantum Wells by Hot Electron Effects

We investigate the effect of Far-Infrared (FIR) radiation on carriers in GaAs/AlGaAs Coupled Quantum Well (CQW) photodiodes. The FIR can induce transitions between the lowest two electronic subbands of our device, which anti-cross as a bias is applied. The effect of FIR on the photocurrent and photoluminescence is studied as a function of the FIR wavelength and the applied bias. We find evidence for the intersubband transition through carrier heating effects.