We present resonant-tunnelling-diode (RTD) oscillators operating at the fundamental frequency of 1111 GHz. show that our RTDs and RTD have much room for further improvement their parameters increase frequencies. The frequencies several THz should be achievable with oscillators. Our study also shows operation beyond relaxation-time limit possible. under are extremely compact (less than a square millimeter) room-temperature sources coherent cw radiation. Such enable plenty real-world applications.

In search for possibilities to increase the operating frequencies of resonant-tunneling diodes (RTDs), we are studying RTDs working in an unusual regime. The collector side our is so heavily doped that depletion region fully eliminated and ground quantum-well subband stays immersed under (or close to) quasi-Fermi level. electron injection from into RTD quantum well very strong comparable emitter whole range biases. Our exhibit pronounced negative-differential-conductance peak-to-valley...

Abstract The review outlines the basic principles of operation resonant-tunnelling diodes (RTDs) and RTD oscillators followed by an overview their development in last decades. Further, we discuss different types RTDs oscillators, limitations due to parasitics, inherent as detectors. We also give present status sub-THz THz several examples applications.

9 μW at the fundamental frequency of 1.09 THz, 15 0.98 and up to 27 lower frequencies 620–660 GHz have been demonstrated with double-resonant-tunneling-diode (RTD) patch-antenna oscillators. These parameters are substantially superior those previously reported for RTD oscillators, they close state-of-the-art level all other types oscillators around 1 THz. However, double-RTD also provide essential advantages compactness, simplicity, vertical emission from chip surface, a high degree...

The nonlinear response of resonant-tunnelling diodes (RTDs) is analysed theoretically at high frequencies (HFs), which are far above the diode’s tunnel-relaxation-time limit. We show that HF I-V curve in this regime substantially different from static one. calculated and oscillation characteristics a RTD oscillator good agreement with our measurement results. Our model applicable to RTDs working THz frequencies.

I have shown that weak variation of the tunnel transparency collector barrier with bias has substantial (and frequently crucial) effect on high-frequency properties resonant-tunneling diodes (RTDs). Also it been real part RTD conductance can be negative and large at frequencies much higher than reciprocal quasibound-state lifetime in quantum well between barriers RTD, if (as opposed to common practice) is heavily doped does not thick spacer layers. The displacement currents are responsible...

The spectral characterization of a broadband antenna using pump-probe photomixing continuous-wave (CW) terahertz (THz) system is presented. high dynamic range the system, comparable to or better than that similar systems reported in literature, provides an accurate means characterization. planar exhibits log-periodic behavior at low frequencies, bow-tie and resonance characteristic between, well agreement with geometry. It predicted improved geometry extends higher frequencies would...

The concept of on-chip double-resonant-tunneling-diode (RTD) patch-antenna oscillator has the virtues compactness, simplicity, high isolation from external circuitry, and increased output power. Relying on this concept, we demonstrate an order magnitude increase in power compared to previous reports RTD oscillators: 10 μW at fundamental frequency 525 GHz 70 330 GHz. Estimates show that significantly higher frequencies powers are achievable with type oscillator. Only optical lithography been...

A model for analyzing dynamic large-signal characteristics of double-barrier resonant-tunneling diodes (RTDs) is presented. The based on the analysis dynamical trajectories in phase space, defined by RTD bias and electron density quantum well. We show that an accurate can be reformulated approximate way, relying only a directly measurable DC I–V curve few other parameters, which could easily estimated with simple calculations. further demonstrate equivalent circuit, composed capacitor,...

We show, first, that the charge relaxation (response) time of resonant-tunneling diode (RTD) can be significantly shorter or longer than resonant-state lifetime, depending on RTD operating point and parameters. Coulomb interaction between electrons is responsible for effect. Second, it also demonstrated frequencies RTDs are limited neither by lifetime nor time; particularly in with heavily doped collector, differential conductance stay negative at far beyond limits imposed constants. provide...

Electro-optical control of the terahertz phase in continuous-wave photomixing systems allows determination both amplitude and with a single sampling point per frequency. It is experimentally demonstrated that spectroscopic measurements can be performed by an order magnitude faster method without performance degradation compared to standard delay line technique.

We have shown, firstly, that the response time (τresp) of double-barrier resonant-tunnelling diode (RTD) can be much smaller as well larger than quasibound-state lifetime in quantum (τdwell). Secondly, real part RTD conductance negative and large at frequencies higher reciprocal τdwell RTDs with a heavily doped collector without spacer layers. The Coulomb interaction electrons emitter is responsible for effects. A simple analytical expression impedance has been derived an equivalent circuit proposed.

We demonstrated that the response time of resonant-tunneling structures (τresp) can be much smaller as well larger than quasibound-state lifetime. A simple analytical expression for impedance diode has been derived, it takes into account Coulomb interaction and equation relating τresp to static differential conductance also obtained; allows one get in measurements current–voltage curve.

A method of electro-optical control the terahertz (THz) phase in continuous-wave photomixing THz systems is suggested and demonstrated. The enables phase-sensitive detection without any moving mechanical components system. Additionally, allows lock-in a chopper, which increases signal-to-noise ratio

We demonstrate an “island” design of on-chip slot-antenna resonant-tunneling-diode (RTD) oscillators, where the contact n++ layer is removed everywhere except for a small island under RTD. At frequencies around 2 THz, this leads to significant reduction (by factor ≈ 2) in total Ohmic losses at conducting surfaces slot antenna. With design, we achieved highest radiated power RTD oscillators frequency range 1.6–1.74 THz with 2.2 μW fundamental 1.74 THz. Theoretical analysis indicates that...

A photonic sub-millimetre (sub-mm) wave transmitter module has been developed and fabricated. The consists of a 1.55 µm waveguide InP photodetector monolithically integrated with planar full slot antenna passive lowpass filter for DC bias supply. For the first time, optical heterodyne 460 GHz sub-mm signal generation is demonstrated. It further shown that can effectively replace classical solid-state oscillator an astronomical superconductor-insulator-superconductor receiver. generates...

The tunnel lifetime of the electrons in quantum well a resonant-tunnelling diode (RTD) is usually assumed to be imposing an inherent fundamental limitation on operating frequencies RTD oscillators. Here, we experimentally demonstrate that one can overcome by heavy doping collector. We present oscillators with oscillation frequency up factor 3 above limitation. Our results indicate limitations RTDs should lie far state-of-the-art contemporary

We show that the maximum output power of a simple resonant-tunneling-diode (RTD) oscillator is fundamentally limited by radiation conductance its antenna and RTD voltage swing. For stand-alone oscillators with common types, this level most likely cannot exceed 1 mW at sub-THz THz frequencies. The current density, conductance, capacitance have no direct influence on but those parameters determine how close one can get to maximum. maxima dc-to-RF conversion efficiency are achieved for...

We present resonant-tunnelling-diode (RTD) oscillators, which are operating at frequencies up to 564 GHz. Due heavy doping of the collector side our diodes, oscillators beyond tunnel-lifetime (τ) and relaxation-time (τrel) limits RTDs. At GHz we achieve ωτ≈1.2 ωτrel≈2.6, highest previously reported value ωτ >150 was ≈0.6. Our study indicates that RTD could be significantly increased RTDs should capable several THz.

The uni-traveling-carrier p-i-n photodiodes have been analyzed both in the ballistic and drift modes of operation. analytical expressions for terahertz (THz) power achievable with derived drift-diffusion approximation, optimum photodiode parameters identified different THz-power limitation mechanisms (space-charge effects, heating, absorption saturation, etc.) considered. It has shown that THz powers on level 300 μW at ≳1 THz, 10 mW 0.3 30 0.1 should be achievable. That would give more than...

We present a theoretical analysis of traveling-wave microstrip resonant-tunneling-diode (RTD) oscillators. Such oscillators are similar to terahertz (THz) quantum-cascade lasers (QCLs) with metal-metal waveguide and just the active part single QCL period (an RTD) as their core. Assuming realistic parameters RTDs, we show that RTD should be working at sub-THz THz frequencies. Contrary contemporary QCLs, microstrips room-temperature The major loss- gain-enhancement mechanisms in identified.