Parallel-plate Ba0.25Sr0.75TiO3 (BST) varactors with a record high Q factor are fabricated on Si substrate. At 45 GHz the is about 40, and tuneability at 25 V more than 40% in measured frequency range 0.045–45 GHz. The improvement achieved by using thick bottom electrode consisting of Pt (50 nm)/Au (0.5 μm) allowing us to reduce microwave losses associated metal layers. BST films exhibit relatively permittivity (150) zero bias resistivity (1010 Ω cm) fields up 700 kV/cm.

We present a flexible terahertz (THz) detector based on graphene field-effect transistor fabricated plastic substrate. At room temperature, this reveals voltage responsivity above 2 V/W and estimated noise equivalent power (NEP) below 3 nW/Hz at 487 GHz. have investigated the effects of bending strain DC characteristics, responsivity, NEP detector, results reveal its robust performance. Our findings shown that is promising material for development THz technology.

This letter presents a graphene field effect transistor (GFET) detector at 400 GHz, with maximum measured optical responsivity of 74 V/W, and minimum noise-equivalent power 130 pW/Hz <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1/2</sup> . shows how the performance degrades as function residual carrier concentration in channel, which is an important material parameter that depends on quality sheet contaminants introduced during fabrication...

A composite right/left handed (CRLH) transmission line (TL) phase shifter, using ferroelectric (Ba/sub 0.25/Sr/sub 0.75/TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> ) varactors as tunable element, is presented for the first time. It theoretically and experimentally demonstrated how unique features of CRLH TLs, enables a differential shift with flat frequency dependence around center frequency. The experimental prototype coplanar...

Experimentally observed resonant absorption peaks in frequency dependent loss tangent thin film parallel-plate SrTiO3 and Ba0.25Sr0.75TiO3 capacitors are explained by electrostriction piezoelectric effects. A simple theory (linear approximation) is proposed to model the electric field temperature dependences of acoustic frequencies, intensities microwave into transformations. The dependence frequencies may be used develop tunable bulk wave resonators (TFBARs) operating at up 10GHz above....

Plasma waves play an important role in many solid-state phenomena and devices. They also become significant electronic device structures as the operation frequencies of these devices increase. A prominent example is field-effect transistors (FETs), that witness increased attention for application rectifying detectors mixers electromagnetic at gigahertz terahertz frequencies, where they exhibit very good sensitivity even high above cut-off frequency defined by carrier transit time. Transport...

Parallel-plate Au(Pt)∕Ba0.25Sr0.75TiO3∕(Pt)Au thin film varactors were fabricated on high resistance Si substrates and characterized at dc, rf, microwave frequencies. In the frequency range 10–45 GHz show relatively low losses, with loss tangent less than 0.025 45 GHz. Due to thick highly conductive Pt/Au electrodes metal losses are 10%. However, of ferroelectric is still three five times higher that in Ba0.27Sr0.73TiO3 single crystal. The analysis dc field dependences permittivity a wide...

Electrically tunable solidly mounted thin film bulk acoustic resonators based on Ba <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> Sr xmlns:xlink="http://www.w3.org/1999/xlink">1-x</sub> TiO xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> films are reported for the first time. The acoustically isolated from silicon substrate by a Bragg reflector stack. Applying DC bias induces piezoelectric effect and an resonance at approximately 4...

Correlations between microstructure and Q-factor of tunable solidly mounted Ba0.25Sr0.75TiO3 (BSTO) thin film bulk acoustic wave resonators are studied using analysis test structures prepared at different growth temperatures the BSTO films varying in range 450-650 °C. The observed changes with temperature correlated related microstructure, including grain size, texture misalignment, interfacial amorphous layer, surface roughness, deterioration Bragg reflector layers. correlations established...

In this letter, we report on the performance of graphene field-effect transistors (GFETs) in which extrinsic transit frequency ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${f}_{T}$ </tex-math></inline-formula> ) and maximum oscillation notation="LaTeX">${f}_{\text {max}}$ showed improved scaling behavior with respect to gate length notation="LaTeX">${L}_{g}$ ). This improvement was achieved by use...

This paper reports on compact tunable true-time delay lines based ferroelectric (Ba/sub 0.25/Sr/sub 0.75/TiO/sub 3/) varactors integrated high-resistivity silicon. The are lumped elements, physically implemented as synthetic coplanar-strip lines. An approximate analytical design procedure, exactly valid for /spl omega//spl rarr/0, is proposed. physical size of the fabricated 2.0/spl times/0.33 mm/sup 2/, including bias pads. Measurements performed from room temperature (RT) down to 80 K....

The tunable solidly mounted Ba0.25Sr0.75TiO3 (BSTO) thin film bulk acoustic wave resonators (TFBARs) with improved Q-factor are fabricated and characterized. BSTO films grown by magnetron sputtering at temperature 600 °C extremely low sputter gas pressure 2 mTorr using on-axis configuration. measured TFBARs is more than 250 mechanical 350 5 GHz resonance frequency. improvement in the associated reduction grain misorientation. latter responsible for generation of shear waves leaking through...

Flexible energy harvesting devices fabricated in scalable thin-film processes are important components the field of wearable electronics and Internet Things. We present a flexible rectenna based on one-dimensional junction metal-insulator-graphene diode, which offers low-noise power detection at terahertz (THz) frequencies. The rectennas polyimide film process by photolithography using graphene grown chemical vapor deposition. A area reduces capacitance enables operation D-band (110 - 170...

Electrically tunable solidly mounted thin film bulk acoustic resonators based on Ba0.25Sr0.75TiO3 and BaTiO3 films are fabricated measured in wide dc bias voltage temperature ranges. At room temperature, the tunability of series parallel resonances for resonator 1.7% 0.3%, respectively, 15V applied over 350nm thick ferroelectric (43V∕μm). The electromechanical coupling coefficient increases with up to 3.7% at 15V. limited partly by quality used films. Potentially, they may be substantially...

The concept of the frequency switching in composite bulk acoustic wave (BAW) resonators based on thin films paraelectric phase ferroelectrics is demonstrated experimentally. BAW Ba0.25Sr0.75TiO3/SrRuO3/Ba0.25Sr0.75TiO3 multilayer structure are fabricated and characterized. It shown that resonance can be switched more than two times (from 3.6 GHz to 7.7 GHz) by changing polarity 5 V dc bias voltage at one ferroelectric layers. performance analyzed using theory field induced piezoelectric...

Lifetime is a critical parameter in ubiquitous, battery-operated sensors for machine-to-machine (M2M) communication systems, an emerging part of the future Internet Things. In this paper, performance radio frequency (RF) to DC energy converters using transparent and flexible rectennas based on graphene ambient RF energy-harvesting scenario evaluated. Full-wave electromagnetic (EM) simulations dipole antenna assuming reported state-of-the-art sheet resistance few-layer, yields estimated ohmic...

Effect of LiNbO3 ferroelectric substrate on the carrier mobility in top gated graphene field-effect transistors (G-FETs) is demonstrated. It shown that, at same residual concentration charge carriers, G-FETs higher than that SiO2/Si substrate. The effect associated with reduction Coulomb scattering via screening charged impurity field by induced substrate, but significant only for mobilities below 1000 cm2/V s. Raman spectra analysis and correlations established between microwave loss...

This paper addresses the high-frequency performance limitations of graphene field-effect transistors (GFETs) caused by material imperfections. To understand these limitations, we performed a comprehensive study relationship between quality and surrounding materials GFETs fabricated on silicon chip. We measured transit frequency (f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</sub> ) maximum oscillation...

The high-frequency performance of top-gated graphene field-effect transistors (GFETs) depends to a large extent on the saturation velocity charge carriers, limited by inelastic scattering surface optical phonons from dielectrics surrounding channel. In this work, we show that, simply changing channel dielectric with material having higher phonon energy, one could improve transit frequency and maximum oscillation GFETs. We fabricated GFETs conventional SiO <sub...

Tunable 5.2 GHz bulk acoustic wave resonators utilizing BaxSr1−xTiO3 ferroelectric films with similar intrinsic properties but different interface roughness are fabricated and characterized. Increase in from 3.2 nm up to 6.9 results reduction Q-factor 350 down 150 due extrinsic losses caused by scattering at reflections rough interfaces other mechanisms associated roughness. The increased is a result of distortion Pt bottom electrode formation heterogeneous enclosures TiO2−x the layer.

Intrinsically tunable 0.67BiFeO3−0.33BaTiO3 (BF–BT) thin film bulk acoustic wave resonators with record high tunability of 4.4% and effective electromechanical coupling coefficient 10% are fabricated analyzed. The analysis, based on the theory dc field induced piezoelectric effect mechanical loading by electrodes taken into account, reveals that enhanced parameters associated inherently BF–BT electrostriction coefficient, which is found to be 5.9 × 1010 m/F. Q-factor up 220 at 4.1 GHz...

A semiempirical model describing the influence of interface states on characteristics gate capacitance and drain resistance versus voltage top gated graphene field effect transistors is presented. By fitting our to measurements capacitance–voltage relating applied Fermi level position, state density found. Knowing allows us fit measured resistance–gate characteristics. The extracted values mobility residual charge carrier concentration are compared with corresponding results from a commonly...

Development of transistors for advanced low-noise amplifiers requires better understanding mechanisms governing the charge carrier transport in correlation with noise performance. In this article, we report on study velocity InGaAs/InP high-electron-mobility (HEMTs) found via geometrical magnetoresistance wide range drain fields, up to 2 kV/cm, at a cryogenic temperature K. We observed, first time experimentally, peaks and that peak corresponding field decrease significantly transverse...