Time Resolution and Power Dependence of Transistor Based Terahertz Detectors

We present a systematic study of time resolution and power dependence of the responsivity of three significantly different types of the Field Effect Transistor based detectors. We analyze photoresponse of custom-made Si junctionless FETs (JLFETs), Si MOSFETs and GaAs-based high electron mobility transistors (HEMT) detectors, which represent structures that are very often employed in experiments dedicated to the detection of sub-THz and THz radiation using FETs. All structures have been monolithically integrated with a log-periodic broad-band planar antenna. Time resolved photoresponse of room temperature detectors have been studied applying nanosecond pulses of monochromatic linearly polarized terahertz laser radiation with frequencies f ranging from 0.6 to 3.3 THz. Our measurements demonstrate that these detectors have nanoseconds response time and very wide dynamic range, both strongly depending on applied FET gate voltages.