Detection of high intensity THz radiation by InP double heterojunction bipolar transistors

We report on the photoresponse of 0.7-μm InP double heterojunction bipolar transistor to THz radiation of low and high intensities, when the collector is unbiased. At low intensities, the photoresponse is linear in radiation intensity. Under intense laser radiation, we observe a saturation at intensities > 15 kW/cm
²
, sample damaging arising around ~ 40 kW/cm
²
. The photoresponse as a function of base-emitter bias dependence does not change with the radiation intensity.