A study has been done of microwave mixing at 20 GHz using the nonlinear (power dependent) resistance thin niobium strips in resistive state. Our experiments give evidence that electron-heating is main cause phenomenon. Also a detailed phenomenological theory for determination conversion properties presented. This capable predicting frequency-conversion loss rather accurately arbitrary bias by examining I-V characteristic, Knowing electron temperature relaxation time, and parameters derived...

This paper reviews the state of rapidly emerging terahertz hot-electron nanobolometers (nano-HEB), which are currently among most sensitive radiation power detectors at submillimeter wavelengths. With achieved noise equivalent close to 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-19</sup> W/Hz xmlns:xlink="http://www.w3.org/1999/xlink">1/2</sup> and potentially capable approaching NEP ~ xmlns:xlink="http://www.w3.org/1999/xlink">-20</sup>...

A theoretical analysis for the noise temperature of a low-temperature hot-electron superconducting mixer has been presented. The contribution both Johnson and electron fluctuations evaluated. limit single-side band device due to intrinsic mechanisms estimated be as low 20–40 K, depending on film material. corresponding bandwidth can large 2–3 GHz, with electron-phonon cooling mechanism. An improvement sensitivity is not necessarily followed by decrease conversion gain bandwidth.

The noise performance of a Nb hot-electron bolometer mixer at 2.5 THz has been investigated. devices are fabricated from 12-nm-thick film, and have 0.30 μm×0.15 μm in-plane size, thus exploiting diffusion as the electron cooling mechanism. rf coupling was provided by twin-slot planar antenna on an elliptical Si lens. experimentally measured double sideband temperature receiver low 2750±250 K with estimated ≈900 K. bandwidth derived both IF impedance measurements ≈1.4 GHz. These results...

We report on the measurement of a very low noise equivalent power 3×10−19 W/Hz1/2 at 620 GHz in superconducting antenna-coupled hot-electron bolometer. The sensing element is micron-size titanium transition-edge sensor with NbTiN contacts fabricated sapphire substrate. high sensitivity due to small device volume, operating temperature, and weak electron-phonon coupling film. Measurements were done using cryogenic black body emitter producing well-controlled femtowatt levels. achieved optical...

We have measured directly the thermal conductance between electrons and phonons in ultrathin Hf Ti films at millikelvin temperatures. The experimental data indicate that electron–phonon coupling these is significantly suppressed by disorder. electron cooling time τε follows T−4 dependence with a record-long value τε=25 ms T=0.04 K. hot-electron detectors of far-infrared radiation, fabricated from such films, are expected to very high sensitivity. noise-equivalent power detector area 1 μm2...

While most experimental studies of kinetic-inductance sensors have been limited so far by the temperature range near superconducting transition, detectors can be very sensitive at temperatures well below where number equilibrium quasiparticles is exponentially small. In this regime, a shift quasiparticle chemical potential under radiation results in change kinetic inductance. We modeled noise characteristics made from disordered Nb, NbC, and MoRe films. Low-phonon transparency interface...

We report on the detection of single photons with {\lambda} = 8 {\mu}m using a superconducting hot-electron microbolometer. The sensing element is titanium transition-edge sensor volume ~ 0.1 {\mu}m^3 fabricated silicon substrate. Poisson photon counting statistics including simultaneous 3 was observed. width photon-number peaks 0.11 eV, 70% energy, at 50-100 mK. This achieved energy resolution one best figures reported so far for devices. Such devices can be suitable calorimetric...

We analyze the performance of graphene microstructures as thermal photon detectors and deduce range parameters that define a linear response. The saturation effects detector operates beyond are described in detail for single-photon (calorimeter). compute effect operating this find sensitive detection occurs such non-linear operation. identify optimum conditions at terahertz frequencies should be feasible.

In this letter, we report on the structural and transport measurements of ultrathin MgB2 films grown by hybrid physical-chemical vapor deposition followed low incident angle Ar ion milling. The as thin 1.8 nm, or 6 unit cells, exhibit excellent superconducting properties such high critical temperature (Tc) current density (Jc). results show great potential these for devices present a possibility to explore superconductivity in at 2D limit.

We present high-performance terahertz (THz) metal-mesh bandpass filters developed to mitigate direct detection effects in sensitive THz receivers based on superconducting hot-electron bolometer (HEB) mixers. These are free-standing 5-micron thick sheets of copper perforated with a periodic array diamond-shaped apertures. The simple aperture design minimizes the effect fabrication (rounding) errors filter performance, allowing precise engineering center frequency (1.5-5.5 THz) while...

The prospects of a YBa2Cu3O7−δ hot-electron bolometer mixer for THz heterodyne receiver are discussed. modeled device is submicron bridge made from 10-nm-thick film on high thermal conductance substrate. performance expected this analyzed in the framework two-temperature model which includes heating both electrons and lattice. Also, contribution phonon diffusion through substrate to normal metal contacts evaluated. intrinsic conversion efficiency noise temperature have been calculated as...

We present a concept for hot-electron direct detector capable of counting single millimeter-wave photons. The is based on microbridge (1 μm size) transition edge sensor made from disordered superconducting film. electron–phonon coupling strength at temperatures 100–300 mK proportional to the elastic electron mean free path l and can be reduced by over an order magnitude decreasing l. contacts are different superconductor with higher critical temperature Nb, which blocks thermal diffusion hot...

We report measurements of the energy resolution ultrasensitive superconducting bolometric detectors. The device is a titanium nanobridge with niobium contacts. A fast microwave pulse used to simulate single higher-frequency photon, where absorbed equal photon energy. This technique allows precise calibration input coupling and avoids problems unwanted background photons. Present devices have an intrinsic full-width at half-maximum approximately 23 THz, near predicted value due thermal...

Hot-Electron Bolometer (HEB) mixers have proven to be the best tool for high-resolution spectroscopy at Terahertz frequencies. However, current state of art NbN suffer from a small intermediate frequency (IF) bandwidth as well low operating temperature. MgB <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> is promising material HEB mixer technology in view its high critical temperature and fast thermal relaxation allowing large IF...

We discuss an implementation of a hot-electron transition-edge sensor (TES) capable counting THz photons. The main need for such calorimeter is spectroscopy on future space telescopes with background limited NEP/spl sim/10/sup -20/ W/Hz/sup 1/2/. micromachined bolometers will unlikely reach sensitivity at temperatures above 10 mK. TES sufficient still have time constant /spl sim/0.1-1.0 ms that too short integrating flux photons arriving rate <100 s/sup -1/. Hot-Electron Photon Counter based...

We are developing hot-electron superconducting transition-edge sensors (TES) capable of counting THz photons and operating at . fabricated Ti nanosensors with Nb contacts a volume on planar Si substrates have measured the thermal conductance in material, G=4times10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> W/K 0.3 K, caused predominantly by weak electron-phonon coupling. The corresponding phonon-noise NEP=3times10...

We report a systematic, comprehensive set of measurements on the dynamics and noise processes in diffusion phonon-cooled superconducting hot-electron bolometer mixers which will serve as ultralow detectors THz heterodyne receivers. The conversion efficiency output devices varying lengths were measured with radio frequency between 8 40 GHz. studied consist 100-Å-thin film Nb bridges connected to thick (1000 Å), high conductivity normal metal (Au) leads. range from 0.08 3 μm. For longer than...

A complex study of the electron-phonon interaction in thin NbC films with electron mean free path $l=2--13\mathrm{nm}$ gives strong evidence that scattering is significantly modified due to interference between and elastic from impurities. The ${T}^{2}$ term, which proportional residual resistivity, dominates over Bloch-Gr\"uneisen contribution resistivity at low temperatures up 60 K. energy relaxation rate directly measured via hot electrons heated by modulated electromagnetic radiation. In...

A hot-electron transition-edge superconducting bolometer with adjustable thermal relaxation speed is proposed. The contacts are made from a superconductor high critical temperature which blocks the diffusion of hot carriers into contacts. Thus electron-phonon interaction only mechanism for heat removal. electrons in nanometre-size Tc = 100-300 mK controlled by elastic electron mean free path l. rate behaves as T4l at subkelvin temperatures and can be reduced factor 10-100 decreasing Then an...

Epitaxial laser deposited YBa2Cu3O7−δ films of ∼50 nm thickness were patterned into detectors consisting ten parallel 1 μm wide strips in order to study nonequilibrium and bolometric effects. Typically, the samples had critical temperatures around 86 K, transition widths 2 K current densities above 1×106A/cm2 at 77 K. Pulsed measurements 0.8 wavelength (17 ps full width half maximum) showed a ∼30 response, attributed electron heating, followed by slower decay. Amplitude modulation band...

Hot-electron bolometer mixers employing thin films of conventional superconducting materials have already been successfully fabricated in the past. Magnesium diboride (MgB <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ) is a promising alternative to superconductors, and we report fabrication study ultrathin MgB down 10 nm deposited by hybrid physical-chemical vapor deposition technique. The showed T...

We compare the performance of 10 and 5 μm thick metal–metal waveguide terahertz quantum-cascade laser ridges operating around 2.7 THz based on a 4-well phonon depopulation active region design. Thanks to reduced heat dissipation lower thermal resistance, material shows an 18 K increase in continuous wave temperature compared material, despite maximum pulsed-mode larger input power density. A 129 is achieved using 15 wide ridge waveguide, which lased up 155 pulsed mode. The use thin regions...