Résumé
Detection of terahertz radiation by two dimensional electron plasma in high electron mobility GaAs∕GaAlAs transistors was investigated at cryogenic temperatures in quantizing magnetic fields. Shubnikov–de Haas oscillations of the detection signal were observed. A double (optical and electrical) modulation technique applied allowed us to study the influence of gated and ungated parts of the transistor channel on the detection. Our results provide a direct experimental evidence that both the gated and ungated plasma participate in the detection and clearly show the necessity to improve theoretical models that usually take into account only the gated part of the channel.This work was supported by Polish 3T11B04528 and 162/THz/2006/02 and European Union MTKD-CT-2005-029671 grants. It was also supported by the CNRS and GDR-E project Semiconductor sources and detectors of terahertz frequencies and by the joint French-Lithuanian research programme Gilibert/EGIDE. We acknowledge also the help of the Region Languedoc–Roussillon through the Terahertz Platform project. One of us (W.K.) acknowledges the support of the Japanese JSPS society.