The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
We discuss how noncontact, quantitative large-area mapping of the conductance of thin films requires delicate corrections in order to deduce electrical properties such as graphene mobility from THz-TDS measurements.
We report on the influence of substrate thickness on the performance of antenna coupled microbolometers for terahertz (THz) detection. Planar antennas with NbsNó microbolometers were fabricated on silicon substrates. Detected voltages of these antenna-coupled microbolometers are altered with a periodic variation from 0.5 THz to 0.75 THz, which is accorded with the reflection of the substrate. By placing...
We present an antenna-coupled 1 × 64 Nb5N6 microbolometer array detectors for real-time terahertz (THz) imaging. The intrinsic average responsivity of the detectors in the array is 650 V/W, and the corresponding noise equivalent power (NEP) is 17 pW/√Hz. The array chip is combined with a low noise readout circuit with 64 channels. The array detector was preliminary used for THz source imaging, and...
We have manufactured mid-infrared chalcogen donor centres in silicon by high-temperature diffusion doping. Electrical characterisation has shown that we can control the ratio of different donor centre concentrations. FT-IR spectroscopy reveals very narrow lines in the mid-infrared spectral band. We have now performed the first time-domain measurements on the donor centre excited states. Our preliminary...
CMOS-compatible, heavily-doped semiconductor films are very promising for applications in mid-infrared plasmonic devices because the real part of their dielectric function is negative and broadly tunable in this wavelength range. In this work we investigate n-type doped germanium epilayers grown on Si substrates. We design and realize Ge nano-antennas on Si substrates demonstrating the presence of...
The article describes a convenient way to numerically model antennas for sub-THz radiation detectors while accounting for multiple oxide layers included in typical silicon substrates used in microelectronic technologies. Several approaches are presented, including a solution based on calculations of effective permittivity of the layered substrate. The results suggest that this approach can work at...
We have applied the terahertz (THz) time-domain spectroscopy (TDS) to revealing the mechanism of the relativistic Doppler reflection of the THz light from a photo-induced plasma layer in a silicon wafer. The velocity of moving plasma layer is estimated by the reflected THz waveforms as a function of pump and probe delay time. We found that the interaction time of the moving plasma front and the reflected...
We applied optical pump — THz probe spectroscopy to a series of polycrystalline thin film silicon solar cells treated using various technological steps. We found a clear correlation between the ultrafast carrier dynamics and the macroscopic parameters (like open-circuit voltage) characterizing the cells in a usual steady-state operation.
In this paper, we have demonstrated a viable microstrip array patch antenna technology for the first time on GaN-on-low resistivity silicon (LR-Si) substrates (ρ < 40 Ω.cm) at H-band frequencies (220–325 GHz). The developed technology is compatible with standard MMIC technology with no requirement for high temperature processes. To mitigate the losses presented by the substrate and to enhance the...
We demonstrate a Fabry-Perot cavity for sensing highly absorbing liquids at terahertz frequencies. A sub-wavelength layer of liquid sample is accommodated between a ground plane and a silicon window. A probing terahertz pulse through the window can interrogate a minute change in the bulk properties of the sample. The sensing is manifested through a shift in the Fabry-Perot resonance. Importantly,...
Mid-infrared intersubband absorption from p-Ge quantum wells with Si0.5Ge0.5 barriers grown on a Si substrate is demonstrated from 6 to 9 μm wavelength at room temperature and can be tuned by adjusting the quantum well thickness. Fourier transform infra-red spectroscopy measurements demonstrate clear absorption peaks corresponding to intersubband transitions among confined hole states. The work indicates...
Graphene, two-dimensionally arranged carbon atoms in honeycomb lattices, has unique optical properties due to its linear dispersion and the massless nature of its carriers. In this paper, we concerned with the spectrum analysis of monolayer graphene film. The pump light from 808 and 1064 nm infrared semiconductor laser with tunable power from 0 to 450mW incident on the samples respectively together...
Using newly developed silicon micromachining technology that enables low-mass and highly integrated receivers, we are developing state-of-the-art terahertz spectrometer instruments for space-based planetary and astrophysics orbiter missions. Our flexible receiver with integrated antenna architecture provides a powerful instrument capability in a light-weight, low-power consuming compact package which...
An active all-optical high-efficiency broadband terahertz device based on an organometal halide perovskite (CH3NH3PM3, MAPbI3)/inorganic (Si) structure is investigated. Spectrally broadband modulation of the THz transmission is obtained in the frequency range from 0.2 to 2.6 THz, and a modulation depth of nearly 100% can be achieved with a low-level photoexcitation power (∼0.4 W/cm2). Both THz transmission...
An unconventional technique for fabricating single-crystal silicon microstructures is employed as a means of achieving high-efficiency terahertz resonators. The resonators are arranged in a homogeneous array, which is designed to operate as an artificial magnetic conductor with potential for applications in compact terahertz antennas. Experimental validation confirms zero phase change of the electric...
We report on a thickness dependence of the terahertz (THz) bull's eye antenna that uses surface plasmon. For the optimization of the device structure and the strong THz field enhancement, we investigate the thickness dependence of substrate for optimization. We achieved a high THz transmission through a sub-wavelength aperture and observed that the main peak has a weak dependence but the side peaks...
We describe the microstructuring of a silicon surface to act as a spatially tunable dielectric layer. As an example, we show FDTD simulations and fabrication results of it used as an antireflective layer optimized for the terahertz region.
In this paper, we present the performance of the first frequency multiplier using the non-linearity of distributed SIS junctions. The prototype doubler based on distributed SIS junction was for the first time able to pump an SIS mixer. The multiplication efficiency of the distributed SIS junction is 15–30 % for a fractional bandwidth of 10% with excellent spectral line purity. The measured −3 dB line...
Monodisperse colloidal gold nanoparticles were self-assembled into ultra-large-area monolayers and used as coating films on intrinsic silicon to improve the optical modulation depth of terahertz (THz) waves. The monolayer does not attenuate the transmission of THz wave but largely boost the generation of electron-hole pairs in silicon. The THz modulation depth of silicon was improved by a factor of...
We examine array configuration and silicon-lens integration of asymmetric-dual-grating-gate high-electron-mobility transistors (A-DGG HEMTs) as plasmonic terahertz detectors in order to enhance their external coupling efficiencies. We demonstrate 4-fold enhancement of the efficiency by an array of four series-connected detectors and 6-fold enhancement by the hyper-hemispherical silicon-lens integration...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.