Mechanisms of rectification of a high-frequency signal by a field-effect heterotransistor with a short channel
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ICS OF SEMICONDUCTOR DEVICES
Mechanisms of Rectification of a High-Frequency Signal by a Field-Effect Heterotransistor with a Short Channel M. L. Orlov Institute for Physics of Microstructures, Russian Academy of Sciences, Nizhni Novgorod, 603950 Russia Submitted May 14, 2007; accepted for publication June 26, 2007
Abstract—The effect of nonlinearity of the drift velocity of free charge carriers and the gradient- and concentration-related nonlinearities in the power–voltage sensitivity of a field-effect transistor with a short channel are studied theoretically. Theoretical results are compared with experimental data on the detection of terahertz radiation. It follows from the comparison that, in order to gain deeper insight into observed systematic features in the analysis of high-frequency characteristics of the transistor, one has to take into account some other mechanisms of the current nonlinearity, in addition to the plasma-related nonlinearity. PACS numbers: 73.40.Lq, 73.50.Mx, 84.40.Dc, 85.30.Tv DOI: 10.1134/S1063782608030184
1. INTRODUCTION At present, the potential of using quantum-mechanical low-dimensional systems in the fabrication of devices of solid-state electronics in the still new terahertz range of frequencies is actively studied. In order to solve the associated problem, it is reasonable to use devices that have been already been used widely and for a long time in microelectronics and nanoelectronics. Foremost among these devices are heterobipolar transistors and short-channel field-effect transistors (FETs) with a two-dimensional (2D) gas of charge carriers in the transport channel. These devices fabricated on the basis of various heterocompositions have been successfully used at frequencies as high as 200 GHz and even higher [1], even if the traditional principles of amplification and conversion of the signal are used. A number of new ideas are also being actively discussed simultaneously with the development of traditional methods of amplification and conversion of electromagnetic signals on the basis of transistors [2, 3]. One of these ideas is related to the use of plasma resonances for detection and generation of electromagnetic signals in the terahertz region of frequencies even at room temperature. However, even the earliest experiments with generation of terahertz radiation by a fieldeffect transistor [4] showed that there are serious difficulties with excitation of oscillations in 2D plasma of a short-channel FET; these difficulties are most probably related to the necessity of sustenance of theoretically recommended [2] certain boundary conditions for the field and current at the source and drain contacts to the channel. The attractiveness of the idea and, simultaneously, the arising difficulties with its practical implementation gave rise to the necessity of preliminary diagnostics of
plasma oscillations in the 2D channel of an FET with the aim of searching for optimal conditions for excitation of these oscillations. The simplest method of attaining this aim is the use of an FET as
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