Electron transport and detection of terahertz radiation in a GaN/AlGaN submicrometer field-effect transistor

Electron transport and photoresponse in the terahertz range in a GaN/AlGaN field-effect transistor with the submicrometer gate (0.25 μm) and two-dimensional electron gas in the channel (the electron concentration n _s = 5 × 10¹² cm^?2) were studied at 4.2 K. The charge-carrier mobility in the transistor’s channel μ = 3500 cm²/(V s) was determined from the dependence of the conductance on magnetic field. It is found that the dependence of photovoltage at the radiation frequency f = 574 GHz on the gate voltage (i.e., on the concentration of two-dimensional electrons) features a characteristic maximum, which is related to a resonance response of the subgate plasma in the transistor channel.