4.3 THz quantum-well photodetectors with high detection sensitivity

We demonstrate a high performance GaAs/AlGaAs-based quantum-well photodetector (QWP) device with a peak response frequency of 4.3 THz. The negative differential resistance (NDR) phenomenon is found in the dark current-voltage (I-V) curve in the current sweeping measurement mode, from which the breakdown voltage is determined. The photocurrent spectra and blackbody current responsivities at different voltages are measured. Based on the experimental data, the peak responsivity of 0.3 A/W (at 0.15 V, 8 K) is derived, and the detection sensitivity is higher than 10¹¹ Jones, which is in the similar level as that of the commercialized liquid-helium-cooled silicon bolometers. We attribute the high detection performance of the device to the small ohmic contact resistance of ~2Ω and the big breakdown bias.