Sub-Terahertz Emission from Field-Effect Transistors

Several commercially available field-effect GaInAs-based transistors were studied as emitters of electromagnetic radiation. The emitters were tested either at room or at liquid helium temperature. To spectrally analyse emitted radiation, we applied three different experimental techniques: a spectrum analyser with antennas and mixers, a Michelson interferometer and a magnetic-field-tunable InSb detector. We show that the emission consists of a fundamental frequency of 11.5 GHz and its multiple harmonics spanning the emission band up to about 400 GHz. Analysis of the results allows us to suggest that the emission is caused by a Gunn effect and a high harmonics content is related to a pulse-like time dependence of the current.