Broadband bias-tunable terahertz photodetector using asymmetric GaAs/AlGaAs step multi-quantum well

In this letter, a broadband bias-tunable terahertz (THz) quantum well infrared photodetector (QWIP) with a GaAs/AlGaAs asymmetric step multi-quantum well using the intersubband transition was proposed, designed, fabricated, and characterized. It is found that the THz QWIP has two photon response peaks at 4.5 THz and 6.5 THz and the bias-tunable photon response in the 4.0–6.5 THz frequency range of the device is attributed to the field-assisted tunneling of electrons in the second excitation subbands to continuum states.