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THz detection by field-effect transistors in magnetic fields: Shallow water vs. deep water mechanism of electron plasma instability

Terahertz Detektion mittels Feldeffekt-Transistoren in magnetischen Feldern: Seichtwasser- versus Tiefwasser-Mechanismen der Elektronplasma-Instabilität
: Sakowicz, M.; Lusakowski, J.; Karpierz, K.; Grynberg, M.; Knap, W.; Köhler, K.; Valusis, G.; Golaszewska, K.; Kaminska, E.; Piotrowska, A.


International journal of high speed electronics and systems 18 (2008), No.4, pp.949-958
ISSN: 0129-1564
Journal Article
Fraunhofer IAF ()
III-V semiconductor; III-V Halbleiter; heterostructure; Heterostruktur; electrical property; elektrische Eigenschaft

Detection of THz radiation by a high electron mobility (HEMT) GaAs/GaAlAs transistor was investigated at 4 K as a function of the magnetic field B. The detection signal (a source - drain photovoltage appearing as a response to THz radiation) was found to be periodic in B(exp -1), i.e., it showed Shubnikow - de Haas oscillations. A Fourier transform of the signal showed a large amplitude component independent of the gate polarization, and a small amplitude component dependent on it. This shows that a HEMT response to the radiation cannot be described either by a plasma instability in gated ("shallow water") or in ungated ("deep water") parts of the channel, but rather by a response of the channel as a whole. This is in a good correspondence with recent experimental evidence of antenna effects in detection of radiation by HEMTs and advanced theoretical models of instability of coupled gated - ungated plasma in HEMTs.