Modeling terahertz radiation detection using field effect transistors beyond cutoff / Nihal Yassin Mohamed Ibrahim ; Supervised Salah E. A. Elnahwy , Nadia H. Rafat

Thesis (Ph.D.) - Cairo University - Faculty of Engineering - Department of Mathematics and Physics

Terahertz (THz) radiation detection using field effect transistors (FET) operated beyond cutoff frequency has emerged in the last two decades as a promising technology. Despite the diverse applications available and the inherent advantages of the semiconductor technology, many challenges still lie in the path of the development of the theory and experiments of this technology. This work attempts to develop a comprehensive model of a FET operated beyond cutoff frequency as a THz detector. The model suggested in this work divides the FET THz detector into three parts: Antenna, extrinsic (coupling), and intrinsic (channel). The intrinsic part can be considered as the core of this work. In this part, non-quasi-static approach based on drift charge transport is used to model the FET above threshold potential and beyond cutoff frequency. The model is used to derive piecewise analytical expressions of the different regimes / subregimes of operation of the FET (linear and saturations regimes). Also the effect of multiple AC input signals incident from different channel ports is considered in details giving rise to the possibility of symmetry point formation where those signals cancel the effect of each-other

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