Field Effect Transistors for Terahertz Detection: Physics and First Imaging Applications

Resonant frequencies of the two-dimensional plasma in FETs increase with the reduction of the channel dimensions and can reach the THz range for sub-micron gate lengths. Nonlinear properties of the electron plasma in the transistor channel can be used for the detection and mixing of THz frequencies. At cryogenic temperatures resonant and gate voltage tunable detection related to plasma waves resonances, is observed. At room temperature, when plasma oscillations are overdamped, the FET can operate as an efficient broadband THz detector. We present the main theoretical and experimental results on THz detection by FETs in the context of their possible application for THz imaging.Comment: 22 pages, 12 figures, review pape

Diodai ir jų taikymas elektronikoje

Knygoje pateikiama trumpa diodų raidos apžvalga nuo kristalinio detektoriaus iki šiuolaikinio Šotkio kontakto ir pn sandūros. Aprašomi fizikiniai procesai, vykstantys idealiuosiuose bei realiuosiuose Šotkio kontaktuose, pn ir pin sandūrose. Parodoma, kaip fizikiniai reiškiniai lemia diodų veikimą ir savybes. Aprašoma šiuolaikinių serijiniu būdu gaminamų puslaidininkinių diodų technologija. Pateikiama labiausiai paplitusių šiuolaikinių diodų taikymo elektronikos grandinėse pavyzdžių, grupuojant juos į skyrius pagal diodų parametrus ir veikimo principus: universalieji (bendrosios paskirties) diodai, didelės galios diodai, aukštadažniai diodai, varaktoriai, stabilitronai (išskyrus optoelektronikoje taikomus fotodiodus, šviesos ir lazerinius diodus). Atskiras knygos skyrius yra skiriamas aktyviosios veikos (galios stiprinimo) diodams. Knygos pabaigoje paminėtos netradicinės ir naujausios diodų technologijos. Mokomoji knyga bus naudinga elektronikos inžinieriams, elektronikos įtaisų ir grandinių projektuotojams

Hot electron effect in degenerate semiconductor tunnel junction

We report on the results of experimental study of free carrier heating in degenerate GaAs tunnel p-n diodes when the carriers are excited by pulsed microwave radiation. Free carrier heating is responsible for the electromotive force in the diode. The magnitude of the electromotive force linearly depends on pulsed microwave power and increases with the decrease in semiconductor lattice temperature. It is almost independent of the pulsed microwave frequency and of p-n junction plane orientation in respect to electric field direction. In the tunnelling regime the dark current in the diode is reduced, however, at high enough forward bias the diffusive current is stimulated due to hot carrier phenomenon

Dissipative Parametric Gain in a GaAs/AlGaAs Superlattice

Funding Information: We are sincerely grateful to Martynas Skapas, Sandra Stanionytė, and Remigijus Juškėnas for superlattice characterization; Linas Minkevičius, Vladimir Maksimenko, and Miron S. Kagan for illuminating discussions. The research activities of K. N. A. were partially funded by the Marius Jakulis Jason Foundation and T. H. was supported, in part, by the Foundation for Polish Science through the IRA Programme co-financed by the EU within SG OP. Publisher Copyright: © 2022 American Physical Society.Parametric generation of oscillations and waves is a paradigm, which is known to be realized in various physical systems. Unique properties of quantum semiconductor superlattices allow us to investigate high-frequency phenomena induced by the Bragg reflections and negative differential velocity of the miniband electrons. Effects of parametric gain in the superlattices at different strengths of dissipation have been earlier discussed in a number of theoretical works, but their experimental demonstrations are so far absent. Here, we report on the first observation of the dissipative parametric generation in a subcritically doped GaAs/AlGaAs superlattice subjected to a dc bias and a microwave pump. We argue that the dissipative parametric mechanism originates from a periodic variation of the negative differential velocity. It enforces excitation of slow electrostatic waves in the superlattice that provide a significant enhancement of the gain coefficient. This work paves the way for a development of a miniature solid-state parametric generator of GHz-THz frequencies operating at room temperature.Peer reviewe

InGaAs Diodes for Terahertz Sensing—Effect of Molecular Beam Epitaxy Growth Conditions

InGaAs-based bow-tie diodes for the terahertz (THz) range are found to be well suited for development of compact THz imaging systems. To further optimize design for sensitive and broadband THz detection, one of the major challenges remains: to understand the noise origin, influence of growth conditions and role of defects for device operation. We present a detailed study of photoreflectance, low-frequency noise characteristics and THz sensitivity of InGaAs bow-tie diodes. The diodes are fabricated from InGaAs wafers grown by molecular beam epitaxy (MBE) on semi-insulating InP substrate under different technological conditions. Photoreflectance spectra indicated the presence of strong built-in electric fields reaching up to 49 kV/cm. It was demonstrated that the spectral density of voltage fluctuations at room temperature was found to be proportional to 1/f, while at lower temperatures, 77–200 K, Lorentzian-type spectra dominate due to random telegraph signals caused by individual capture defects. Furthermore, varying bias voltage, we considered optimal conditions for device room temperature operation in the THz range with respect to signal-to-noise ratio. The THz detectors grown with beam equivalent pressure In/Ga ratio equal to 2.04 exhibit the minimal level of the low-frequency noise, while InGaAs layers grown with beam equivalent pressure In/Ga ratio equal to 2.06 are found to be well suited for fabrication of room temperature bow-tie THz detectors enabling sensitivity of 13 V/W and noise equivalent power (NEP) of 200 pW/√Hz at 0.6 THz due to strong built-in electric field effects