DC Measurements Research Articles

Research on the Technology of Improving the Compatibility of DC Measurement Devices Based on the Operation Experience of Siemens Hardware Solutions

The aim of this study was to manufacture alternative Siemens DC measurement system equipment to solve the problems of increased failure rates of foreign DC measurement equipment and the stopped production of key parts. In this paper, the overall structure and common faults of the Siemens DC measurement system are introduced, the difference between TDM signal frame structure and FT3 frame structure is detailed, and the related functional structure, chip type, and function of the Siemens distal module and merging unit (including laser function) are studied. The remote module, merging unit (including laser function), and related hardware design and software design to replace the Siemens DC measurement system were developed, and the test environment and control protection, fault recording wave for communication, and other functional tests were built. The test results show that the domestic remote module, merging unit (laser function), and other technologies communicate normally with the existing Siemens and the domestic mainstream manufacturers, and the accuracy meets the requirements of the 0.2 level.

A Nonlinear Model of RF Switch Device Based on Common Gate GaAs FETs

ABSTRACTThis paper presents a novel method for nonlinear modeling GaAs field‐effect transistors (FETs) in a common gate (CG) configuration, which is crucial for the effective design and thorough assessment of RF switch circuits. By focusing solely on a CG‐based GaAs FET for RF switch device characterization and modeling, the modeling process is streamlined compared to traditional methods that involve both CG and common source (CS) devices. The direct measurement of both DC and RF characteristics using the CG device enhances the accuracy of model parameter extraction. This approach ensures consistency in model and simulation applications as the CG topology aligns with devices commonly found in RF switch circuits. Moreover, to enhance predictive accuracy regarding the dispersion effect, an improved equation of drain‐source current has been incorporated. The empirical validation of the model reveals good agreements in terms of insertion loss, isolation, and output power performance for the CG GaAs FET device, including a wide band single‐pole double‐throw (SPDT) switch Monolithic Microwave Integrated Circuit (MMIC).

The Impact of Gate Annealing on Leakage Current and Radio Frequency Efficiency in AlGaN/GaN High-Electron-Mobility Transistors

Gallium Nitride (GaN) high-electron mobility transistors (HEMTs) are highly promising for high-frequency and high-power applications due to their superior properties, such as a wide energy bandgap and high carrier density. The performance of GaN HEMTs is significantly influenced by the interfacial states of the AlGaN barrier, and gate annealing has emerged as a key process for reducing leakage currents and enhancing DC/RF characteristics. This research investigates the impact of gate annealing on AlGaN/GaN HEMTs, focusing on two main aspects: leakage current reduction and improvements in DC and RF efficiency. Through comprehensive electrical analysis, including DC and RF measurements, the effects of gate annealing were experimentally evaluated. The results show a significant reduction in gate leakage current and noticeable improvements in DC/RF performance for the devices that underwent gate annealing. The study confirms that the annealing process can effectively enhance device performance by modifying the material properties at the gate interface.

Insight into the Structural Optimization and Electrical Conductivity of NiII/MnII Bipyridine–Dicyanamide Complexes

AbstractTwo monomeric octahedral complexes {[Ni(N(CN)2)2(bpy)2]2·H2O (1) and [Mn(N(CN)2)2(bpy)2] (2) where bpy = 2,2′‐bipyridine} were synthesized and characterized by single crystal X‐ray diffraction, elemental analysis, UV–visible, and IR spectra. The geometry optimization through DFT measurements predicts that both the complexes have similar monomeric structures with hexa‐coordinated metal centers having a couple of bpy and mononegative dca anions and thus satisfying the octahedral geometry. Moreover, it is found that the HOMO–LUMO energy gaps are ΔE = 4.981 and 5.563 eV for complexes 1 and 2, respectively, which are responsible for the stabilization of the complex formation. The calculated absorption bands are located at 304 and 235 nm, which are in excellent agreement with the experimental result. Moreover, the DFT study of the electronic spectra of both complexes shows that the calculated absorption bands are in well agreement with the experimental results. In the electrical studies, direct current (dc) measurements on the copper/complex (1 or 2)/copper structure confirm a definite development in the device current with applied bias. Complex 1 has shown better electrical conductance compared to complex 2 based on the reduction of device resistance.

Electrodeposited zinc cellulose nanocrystals composite coatings: Morphology, structure, corrosion resistance and electrodeposition process

Nanoparticles, particularly ceramic, have been widely investigated as beneficial additives in electrodeposited zinc coatings. However, exploiting cellulose-based nanocrystals derived from plant sources is attractive due to their cost-effectiveness and sustainability. In this work, we assessed the impact of various concentrations of cellulose nanocrystals, ranging from 0 to 8 v/v%, on the characteristics of zinc coatings obtained through electrodeposition. We investigated the morphology and structure of the zinc deposits using scanning electron microscopy (SEM), x-ray diffraction (XRD), and confocal microscopy (CM). Corrosion resistance was evaluated through mass loss measurements and electrochemical tests including DC (potentiodynamic polarization) and AC (electrochemical impedance spectroscopy) measurements. Increasing cellulose nanocrystal concentrations up to 7 v/v% notably enhanced the corrosion resistance in 0.5 M NaCl solution. In comparison to coatings with no cellulose addition, the 7 v/v% cellulose concentration resulted in: i) an increase in polarization resistance from 586 Ω cm2 to 1850 Ω cm2, ii) a decrease in corrosion current density from 3.21 × 10−5 A/cm2 to 0.76 × 10−5 A/cm2, and iii) a reduction of the corrosion rate from 0.15 mm/year to 0.08 mm/year assessed after 24-h immersion. Furthermore, the addition of this optimal concentration of nanocrystals enhanced current efficiency to approximately 95%, without compromising microhardness, which remained around 184 HV0.1. Additionally, the incorporation of cellulose nanocrystals resulted in a more compact coating with reduced roughness (Ra ∼0.69 μm). This work thus showcases the significant and beneficial impact of cellulose nanocrystals in producing enhanced electrodeposited zinc coatings.

Osmium(III) Acetylacetonate and Its Missing Polymorph: A Magnetic and Structural Investigation.

Despite the potential for their application, the magnetic behavior of complexes containing 4d and 5d metal ions is underexplored, evidencing the need for benchmark multi-technique studies on simple molecules. We report here a structural and magnetic study on osmium(III) acetylacetonate [Os(acac)3]. X-ray single crystal diffraction did not allow us to determine the structure of the β-polymorph of [Os(acac)3]. The combined magnetic (dc magnetic measurements on powder and cantilever torque magnetometry on single crystal) and spectroscopic (electron paramagnetic resonance, EPR) characterization is here used to provide further evidence that its structure is indeed the one of the orthorhombic "missing polymorph", analogous to the ruthenium(III) derivative. Our study shows that all acetylacetonate complexes of the eighth group of the periodic table show dimorphism and are isomorphic. The EPR characterization allowed the experimental assessment of the easy axis nature of the ground doublet and the determination of the first hyperfine coupling in an osmium complex. Torque magnetometry, applied here for the first time on an osmium-based molecule, determined the orientation of the easy axis along the pseudo C3 axis of the complex. Ac magnetometric measurements revealed in-field slow relaxation of the magnetization further slowed by the suppression of dipolar fields via magnetic dilution in the isostructural gallium(III) analogue.

AC Electric Conductivity of High Pressure and High Temperature Formed NaFePO4 Glassy Nanocomposite.

Olivine-like NaFePO4 glasses and nanocomposites are promising materials for cathodes in sodium batteries. Our previous studies focused on the preparation of NaFePO4 glass, transforming it into a nanocomposite using high-pressure-high-temperature treatment, and comparing both materials' structural, thermal, and DC electric conductivity. This work focuses on specific features of AC electric conductivity, containing messages on the dynamics of translational processes. Conductivity spectra measured at various temperatures are scaled by apparent DC conductivity and plotted against frequency scaled by DC conductivity and temperature in a so-called master curve representation. Both glass and nanocomposite conductivity spectra are used to test the (effective) exponent using Jonscher's scaling law. In both materials, the values of exponent range from 0.3 to 0.9, with different relation to temperature. It corresponds to the electronic conduction mechanism change from low-temperature Mott's variable range hopping (between Fe2+/Fe3+ centers) to phonon-assisted hopping, which was suggested by previous DC measurements. Following the pressure treatment, AC conductivity activation energies were reduced from EAC≈0.40 eV for glass to EAC≈0.18 eV for nanocomposite and are lower than their DC counterpart, following a typical empirical relation with the value of the exponent. While pressure treatment leads to a 2-3-orders-of-magnitude rise in the AC and apparent DC conductivity due to the reduced distance between the hopping centers, a nonmonotonic relation of AC power exponent and temperature is observed. It occurs due to the disturbance of polaron interactions with Na+ mobile ions.

Self-Sensing Potential of Metashale Geopolymer Mortars with Carbon Fiber/Graphite Powder Admixtures

Multifunctional building materials with self-sensing capability have great potential for civil engineering applications. The self-sensing capability of typically calcium aluminosilicate matrices of cementitious or geopolymer materials is adopted by admixing electrically conductive admixtures in an amount that ensures optimal electrical properties and their proportionality to mechanical loading. The paper aims to evaluate the self-sensing capability of 4 metashale geopolymer mortars with graphite powder (GP) and carbon fibers (CF) in different ratios, including MGF 5/0, MGF 4.5/0.5, MGF 4/1, and MGF 3/0. The 4-probe measurements at 21 V DC input voltage on (100 × 100 × 100) mm3 samples with embedded copper-grid electrodes evaluate the gauge factor, which corresponds to the monitored changes in electrical resistivity. Despite the limitations of DC measurements, the self-sensing capability is observed for all the mixtures. The most promising response to dynamic loading with an FCR of 0.018%, is observed for the MGF 4.5/0.5 sample.

Programmed Heterostructures for Enhanced Electrical Conductivity.

Interfacial electron transport in multicomponent systems plays a crucial role in controlling electrical conductivity. Organic-inorganic heterostructures electronic devices where all the entities are covalently bonded to each other can reduce interfacial electrical resistance, thus suitable for low-power consumption electronic operations. Programmed heterostructures of covalently bonded interfaces between ITO-ethynylbenzene (EB) and EB-zinc ferrite (ZF) nanoparticles, a programmed structure showing 67 978-fold enhancement of electrical current as compared to pristine NPs-based two terminal devices are created. An electrochemical approach is adopted to prepare nearly π-conjugated EB oligomer films of thickness ≈26nm on ITO-electrode on which ZF NPs are chemically attached. A "flip-chip" method is employed to combine two EB-ZnFe2O4 NPs-ITO to probe electrical conductivity and charge conduction mechanism. The EB-ZnFe2O4 NPs exhibit strong electronic coupling at ITO-EB and EB-NPs with an energy barrier of 0.13eV between the ITO Fermi level and the LUMO of EB-ZF NPs for efficient charge transport. Both the DC and AC-based electrical measurements manifest a low resistance at ITO-EB and EB-ZF NPs, revealing enhanced electrical current at ± 1.5V. The programmed heterostructure devices can meet a strategy to create well-controlled molecular layers for electronic applications toward miniaturized components that shorten charge carrier distance, and interfacial resistance.

Electrical modeling of an electrochemical sensor operating at the redox cycling mode

In this work, the direct current vs. voltage (DC) characteristics, and the alternate current (AC) impedance of a 1D four-electrode electrochemical cell, operating under redox-cycling conditions, are presented and discussed. The analysis refers to a four-electrode electrochemical system with one positively biased working electrode, one negatively biased working electrode, one auxiliary electrode, and one reference electrode operating in a redox cycling mode. This configuration is useful, for example, for electrochemical biosensors that can benefit from the inherent redox-cycling amplification of the apparatus. An aqueous buffered electrolyte is assumed, containing electrochemically active species that can be oxidized on the anode, with a positive overpotential. Meanwhile, the product of the oxidation reaction can diffuse to the other working electrode which has a negative overpotential, where the product is reduced. The analysis in this paper assumes that oxidation is the dominant mechanism at the anode, reduction is the dominant mechanism at the cathode, and the transport between them is dominated by diffusion. Since it is a 1D model, an ideal lossless redox cycling, i.e. both working electrodes’ currents (anodic and cathodic) are of the same magnitude with opposite signs, is assumed. Next, the small signal (AC) impedance of the electrochemical cell was calculated assuming that the AC signal modifies the oxidation reaction rate at the anode while the reduction reaction rate at the cathode is fixed. The impedance under redox cycling is calculated vs. frequency for various oxidation and reduction rates and both Bodé and Nyquist plots of the impedance are presented. The last part of the paper presents measured data for both DC and AC (i.e. Bodé and Nyquist plots) experiments with interdigitated array (IDA) electrodes, 5 & 10 μm spacing, operating under redox cycling conditions. The DC measurements were conducted in a 6 mM ferricyanide [K3Fe(CN)6] in 0.1 M Phosphate Buffer Saline (PBS) solution, pH 7.4. The AC measurements were conducted in 10 mM & 100 nM ferricyanide (K3Fe(CN)6) in 100 mM KNO3 aqueous electrolyte. A critical discussion follows the results section where the highlights and problems of the models are discussed.

Comprehensive characterization of a high‐performance double heterojunction InGaAs pHEMT for linear power‐efficient amplifiers applications

AbstractThis article centers its attention on the phenomenon of electrostatics, linearity, analogue, and RF performance of a 0.5 μm × (2 × 100) μm double heterojunction AlGaAs/InGaAs/GaAs pHEMT using on‐wafer DC and RF measurements up to 50 GHz. With a high ION/IOFF ratio (1.21 × 107) and low subthreshold slope (72.7 mV/dec), a flat and high transconductance over a wide range of Vgs has been achieved for the tested device. Furthermore, the input intercept and higher‐order voltage intercept point both attained large values with low intermodulation and harmonic distortion. Regarding RF parameters, the intrinsic gain has been achieved up to 28 dB. The GBW up to 750 GHz was attained, with the highest fT and fmax values being 24.5 GHz and 99.3 GHz, respectively. Since the device has very low intrinsic capacitance, parameters like TFP, GFP, and GTFP also showed excellent results. The high intrinsic gain and TGF indicate ample potential of the device for use as an amplifier. Investigating the parameters reveals the device to have very good linearity and amplifying capability.

Characterization of magnetic properties, including magnetocaloric effect, of RE5Pt2In4 (RE = Gd-Tm) compounds

The RE5Pt2In4 (RE = Gd-Tm) rare earth compounds have been investigated by means of X-ray diffraction (XRD) as well as by DC and AC magnetometric measurements. The compounds crystallize in an orthorhombic crystal structure of the Lu5Ni2In4-type (Pbam space group, No. 55). With decreasing temperature, the intermetallics undergo a transition from para- to ferro-/ferri- (RE = Gd, Tb, Ho, Er) or antiferromagnetic state (RE = Tm). In case of Dy5Pt2In4, the ferromagnetic state is reached through an intermediate antiferromagnetic order present in a limited temperature range. The critical temperatures of magnetic ordering range from 4.1 K (RE = Tm) up to 108 K (RE = Tb). For the majority of investigated compounds, a cascade of additional magnetic transitions is found below the respective critical temperatures of magnetic ordering. The magnetic moments are found solely on the rare earth atoms, while the moments of the remaining Pt and In atoms are absent or are too small to be detected while accompanied by the strong rare earth’s moments. The magnetocaloric (MCE) performance of RE5T2In4 (RE = Gd-Tm) is found quite good, especially while taking into account the compounds with RE = Ho and Er. Maximum magnetic entropy change (−ΔSMmax) reaches 11.8 (RE = Ho) or 11.4 J ⋅ kg−1 ⋅ K−1 (RE = Er) under magnetic flux density change of 0–9 T. Under the same conditions, the relative cooling power (RCP) and refrigerant capacity (RC) equal 607 and 495 J ⋅ kg−1 (RE = Ho) or 434 and 341 J ⋅ kg−1 (RE = Er).

DTT toroidal field conductor samples test in Sultan: DC and AC characterization

The superconducting magnet system of the Divertor Tokamak Test (DTT) facility, composed of 18 toroidal field (TF) coils, 6 poloidal field coils and a central solenoid, has been designed and many procurements have been launched. Some manufacturing aspects and some conductor features require characterization under relevant close-to-operative conditions. To confirm the design choices in all details, cryogenic tests in qualified facilities have been foreseen. In this work, the results of the TF samples characterization at the SULTAN facility at the Swiss Plasma Centre (SPC, EPFL) are presented. The 3 week test campaign started on July the 8th, 2022. The DTT TF SULTAN sample was made of two Nb3Sn cable-in-conduit conductor ‘legs’, namely ‘TF-A’ and ‘TF-B’, made with wires produced by Kiswire Advanced Technology, differing for the cabling twist pitch sequence only, and designed to work in DTT at 42.5 kA at 11.9 T peak field. The extensive characterization comprised 3000 electro-magnetic (EM) cycles and two warm-up-cool-down (WUCD) steps, and in detail it included: AC measurements on the virgin conductors, on cyclic loaded conductors and after WUCDs; DC tests at 10.85 T/42.5 kA with intermediate EM cycles at 10.85 T/45 kA before and after WUCDs; DC tests using partial Lorentz force loads, and Minimum Quench Energy tests at 9 T/42.5 kA after cycles and WUCDs. The results of the DC measurement analysis verified the design, in terms of current sharing temperature (T cs) and critical current (I c), as both samples are over the minimum acceptance values. In particular, the ‘TF-A’ sample, characterized by a so-called ‘long twist pitch’ cabling sequence, showed higher performance without any degradation with loading and WUCD cycles, whereas sample ‘TF-B’ presented an initial T cs reduction that afterwards substantially remained unchanged. In terms of strain acting at the Nb3Sn filaments level, this result can be described by a lower effective strain in the ‘TF-A’ sample. AC losses were measured with a calorimetric method as a function of frequency for each series of AC sinusoidal pulsing measurements, and the characteristic coupling time constants were determined.

Direct calibration of a true-rms ac voltmeter against a He-free pulsed Josephson standard

Starting from 2019 a new central role is played by quantum standards, owing to the redefined SI, where electrical units are directly linked to the fundamental constants e (elementary charge) and h (Planck constant). Thus, metrologists are nowadays trying to extend the astonishing accuracy attainable in dc measurements to ac and beyond, moving towards calibrations aiming quantum ac voltage generation. Programmable Josephson Voltage Standards are nowadays capable of fulfilling primary metrology requirements only for stepwise-approximated voltage signals up to few hundreds Hz. Pulsed Josephson standards are instead capable of generating arbitrary waveforms at higher frequencies, so are generally called Josephson Arbitrary Waveform Standards (JAWS). Despite of the lower attainable voltage, JAWS are very promising and are the subject of intense research activity. In particular, the capability of generating high spectral purity signals allows high accuracy measurements especially at the low voltage levels (<100mV rms), which are challenging to be performed by the traditional ac-dc transfer difference using thermal converters. We report in the following about our setup for quantum-based calibrations of a true-rms ac voltmeter with low uncertainty, first results obtained and unsolved issues.

Double percolation approach for hybrid graphene Nanoplatelet-Carbon black nanocomposites based on electrical impedance Spectroscopy

A double-percolation model for predicting electrical properties in hybrid carbon black (CB)-graphene nanoplatelet (GNP) nanocomposites is proposed. This model is based on DC and EIS measurements. From DC measurements, a non-ohmic behavior is observed for low-filled nanocomposites whereas at high-filled ones, an ohmic behavior is noticed. From EIS analysis, the behavior of the system can be modeled by an equivalent circuit formed by a series of inductance-resistance capacitance (LRC), for contact and intrinsic electrical mechanisms, and resistance–capacitance (RC) elements, for tunneling transport, where the capacitances are substituted by Constant Phase Elements (CPEs) due to the presence of scattering effects. The complex impedance analysis shows a GNP-dominated electrical behavior at a high CB/GNP ratio. At a medium CB/GNP ratio a double percolating network is formed. At a low CB/GNP ratio, the electrical transport is CB-dominated. The proposed model based on the classical percolation theory with a double threshold properly fits the electrical measurements.

Adaptive impedance matching in microwave and terahertz metamaterial absorbers using PIN diodes and GaN HEMTs

Metamaterial absorbers allow electromagnetic waves to be converted into heat energy based on impedance matching. However, passive metamaterial absorbers exhibit fixed absorption characteristics, limiting their flexibility. This work demonstrates tunable microwave and terahertz absorbers by integrating adjustable resistors into the metamaterial units. First, a microwave absorber from 1 to 5 GHz was designed by embedding PIN diodes with voltage-controlled resistance. Calculations, simulations, and measurements verified two separate absorption peaks over 90% when optimized to a resistance of 250 Ω. The absorption frequencies shifted based on the resistor tuning. Building on this, a terahertz absorber was modeled by substituting gallium nitride high electron mobility transistors (GaN HEMTs) as the adjustable resistor component. The GaN HEMTs were controlled by an integrated gate electrode to modify the two-dimensional electron gas density, allowing resistance changes without external voltage terminals. Simulations revealed two absorption peaks exceeding 90% absorption at 0.34 THz and 1.06 THz by adjusting the equivalent resistance from 180 Ω to 380 Ω, and the tunable resistance is verified by DC measurement of single GaN HEMT in the unit. This work demonstrates how integrating adjustable resistors enables dynamic control over the absorption frequencies and bandwidths of metamaterial absorbers. The proposed geometries provide blueprints for tunable microwave and terahertz absorbers.

Tunnel-Structured Phosphate Exhibiting High Proton Conductivity and Thermal Stability over a Wide Intermediate Temperature Range.

For the practical application of fuel cells in vehicles, it is a challenge to develop a proton solid electrolyte that coexhibits thermal stability and high proton conductivity at wide intermediate temperatures. Here, we report on the tunnel structured phosphate KNi1-xH2x(PO3)3·yH2O, which exhibits high proton conductivity at room temperature up to 500 °C, with the conductivity value reaching 1.7 × 10-2 S cm-1 at 275 °C for x = 0.18. This material, composed of the smallest cations that form the tunnel framework with face-shared (KO6) and (NiO6) chains and PO4 tetrahedral chains, retained the rigid framework up to 600 °C. Two oxygen sites of water molecules located adjacent to each other along the PO4 tetrahedral chains in the tunnel provided the proton conduction pathway. The sample maintained a conductivity of 5.0 × 10-3 S cm-1 for 10 h at 150 °C while changing the measurement atmosphere to a N2 gas flow, a 4% H2-96% Ar gas flow, and an O2 gas flow. The conductivity value at x = 0.18 obtained from the DC measurement was in the order of 10-6 S cm-1, close to the instrument's measurement limit. These results demonstrate that tunnel phosphate has potential as a proton solid electrolyte for next-generation fuel cells.

An Analysis on Hedging Strategies of Corporates under Ukraine Conflict

The Russia-Ukraine conflict has precipitated significant market volatility, notably affecting the energy and agricultural sectors. This paper offers a concise analysis of corporate hedging tactics in this tumultuous context. Specifically, it examines the energy sector's reaction to fuel price escalations and supply disruptions, highlighting Trafigura Group's revised risk management strategies utilizing financial derivatives to combat market unpredictability. Concurrently, the paper scrutinizes the Louis Dreyfus Company's (LDC) strategic response within the agricultural domain, acknowledging DC's proactive risk management measures, including asset insurance, alternative operational frameworks, and advanced risk assessment protocols. Additionally, the paper delves into the strategic allocation of gold as a corporate hedging instrument amidst geopolitical strife, evaluating its historical efficacy, crisis performance, and status as a potential financial refuge. The discourse concludes by articulating the imperative for adaptive, ongoing recalibration of corporate hedging strategies, underlining the integration of conventional assets like gold for comprehensive risk management amidst the ongoing Russia-Ukraine crisis.

Supercurrent noise in a phase-biased superconductor-normal ring in thermal equilibrium

In superconductor-normal-superconductor (SNS) junctions, supercurrent is mediated via Andreev bound states (ABSs) controlled by the phase difference between the two superconductors. Theory has long predicted significant noise of such supercurrent in equilibrium, due to thermal excitation between the ABSs. Via the fluctuation-dissipation theorem (FDT), this leads to a finite dissipative conductance that coexists with the supercurrent but is hidden in dc measurement. Here, we directly measure the supercurrent noise at radio frequency in a phase-biased SNS ring inductively coupled to a superconducting resonator. We also measure the admittance of the same system whose real part is the dissipative conductance, and quantitatively verify the FDT relation of the SNS ring. The dissipative conductance shows a 1/T temperature dependence, in contrast to the Drude conductance of an unproximitized metal. Using linear response theory, we attribute this behavior to the enhanced current correlations due to the electron-hole symmetry imposed by the proximity effect. Our results reveal the commonly overlooked role of thermal fluctuations in superconducting hybrid systems and other mesoscopic or quantum material systems with large orbital susceptibility. Published by the American Physical Society 2024

Measuring the permittivity of fused silica with planar on-wafer structures up to 325 GHz

Fused silica has become an interesting alternative to silicon for millimeter-wave (mmWave) applications. Unfortunately, there are a few reports on the measurement of fused silica's permittivity above 110 GHz that use electrical rather than optical methods. Given that mmWave applications use electrical circuits, additional electrical data would be useful to industry. To test the feasibility of electrical methods, we applied on-wafer techniques based on coplanar waveguide transmission lines to measure the complex permittivity of fused silica to 325 GHz. Our approach used the multiline thru-reflect-line algorithm on the scattering parameter measurements of transmission lines. Our method combined these results with dc measurements of the resistivity of the metals, simulations of the coplanar waveguide cross section, and dimensional metrology. In short, our measurements do not show significant dielectric dispersion for fused silica up to 325 GHz. The resulting complex permittivity was ϵr=3.87±0.03 and a loss tangent tanδ&amp;lt; 0.005 from 320 MHz to 325 GHz. To support our conclusions, we performed an uncertainty analysis considering relevant sources of uncertainty. In the broader context, these results show that fused silica is a suitable substrate for mmWave electronics where the loss tangent must be less than 0.005 up to 325 GHz.