Henri Happy

A new method for on wafer noise measurement

A method for measuring the noise parameters of MESFETs and HEMTs is presented. It is based on the fact that three independent noise parameters are sufficient to fully describe the device noise performance. It is shown that two noise parameters, R/sub n/ and mod Y/sub OPT/ mod , can be directly obtained from the frequency variation of the noise figure F/sub 50/ corresponding to a 50 Omega generator impedance. By using a theoretical relation between the intrinsic noise sources as additional data, the F/sub 50/ measurement only can provide the four noise parameters. A good agreement with more conventional techniques is obtained. >

Lysozyme detection on aptamer functionalized graphene-coated SPR interfaces.

The paper reports on a surface plasmon resonance (SPR)-based approach for the sensitive and selective detection of lysozyme. The SPR sensor consists of a 50 nm gold film coated with a thin film of reduced graphene oxide (rGO) functionalized with anti-lysozyme DNA aptamer. The SPR chip coating with rGO matrix was achieved through electrophoretic deposition of graphene oxide (GO) at 150 V. Electrophoretic deposition resulted in partial reduction of GO to rGO with a thickness depending on the deposition time. For very short time pulses of 20 s, the resulting rGO film had a thickness of several nanometers and was appropriate for SPR sensing. The utility of the graphene-based SPR sensor for the selective and sensitive detection of proteins was demonstrated using lysozyme as model protein. Functionalization of rGO matrix with anti-lysozyme DNA aptamer through π-stacking interactions allowed selective SPR detection of lysozyme. The graphene-based SPR biosensor provides a means for the label-free, concentration-dependent and selective detection of lysozymes with a detection limit of 0.5 nM.

Improved Monte Carlo algorithm for the simulation of /spl delta/-doped AlInAs/GaInAs HEMTs

A classical Monte Carlo (MC) device simulation has been modified to locally introduce the effects of electron degeneracy and nonequilibrium screening. Its validity in the case of AlInAs/GaInAs HEMTs has been checked through the comparison, first, with a quantum Schrodinger-Poisson (SP) simulation in the case of a complicated layer structure, which is actually used in the fabrication of real devices, and second, with experimental results of static characteristics of recessed /spl delta/-doped HEMTs.

Scalable Electrical Compact Modeling for Graphene FET Transistors

A new scalable electrical compact model for the Graphene FET devices is proposed. Starting from Thieles quasianalytical model, the equations are modified to be fully compatible with SPICE-like circuit simulation. Compared to Meric et al. model, the charge model is improved. This large signal model has been implemented in Verilog-A code and can be used for simulation in a standard circuit design environment such as Cadence or ADS. This model has been verified using different measurements from the literature, and furthermore, its scalability is demonstrated.

Microscopic noise modeling and macroscopic noise models: how good a connection? [FETs]

Based on the active line concept, a novel approach for the calculation of the high frequency noise performance of field effect transistors (FET) is proposed. By using a simple analytical theory, the FET small signal equivalent circuit as well as the macroscopic noise sources and their correlation are calculated for different two-port terminations. Values of the usual dimensionless noise parameters P, R, C, gate noise temperature T/sub g/ and drain noise temperature T/sub d/ are then given and discussed. By comparison with a more realistic numerical modeling of the noise performance, the validity of the analytical noise model is discussed. The validity of Pospieszalskis noise model and its relations with Pucels one is emphasized. >

Influence of the gate leakage current on the noise performance of MESFETs and MODFETs

Abstract In this paper, the influence of the gate leakage current on the noise performance of MESFETs and MODFETs is investigated. Both a simple analytical model and a more realistic numerical model have been developed. It is shown that the noise performance is strongly dependent on the gate leakage current value, especially at low frequency. The theoretical results are discussed and compared with experimental ones.

Fabrication and characterization of low-loss TFMS on silicon substrate up to 220 GHz

This paper presents the results of the fabrication and characterization up to 220 GHz, of thin-film microstrip (TFMS) transmission-line structures. The transmission lines are fabricated on a low-resistivity silicon substrate (/spl rho/=10 /spl Omega/ /spl middot/ cm). TFMS lines with a thick dielectric layer (20 /spl mu/m of benzocyclobutene is used here) present losses of 0.3 dB/mm at 94 GHz and 0.6 dB/mm at 220 GHz. Thus, using this technology, it will be possible to develop monolithic microwave integrated circuits on a silicon substrate.

Wide- and narrow-band bandpass coplanar filters in the W-frequency band

This paper deals with the design of passive coplanar devices in the W-frequency band. As long as coplanar transmission lines are correctly dimensioned, analytical models based on quasi-TEM approximation can be used. Such models are associated with a correct definition of the reference planes at the junctions and employed for junction discontinuities, T- and cross-junctions. In order to validate these assertions, simulated and experimental data on classical quarter-wavelength shunt-stub filters are first presented. Then the design of traditional coupled-line filters is examined. The problems in terms of insertion loss associated with these kinds of narrow-band applications are discussed here. Minimization of insertion losses requires increasing the width of the strips. Consequently, the design becomes complex and modeling using transmission-line models less accurate. Nevertheless, as an optimization procedure is needed to tune the filter theoretically, such a very fast design method is necessary. Simulated and experimental results in the range 500 MHz to 110 GHz are compared throughout the paper.

Measurement Techniques for RF Nanoelectronic Devices: New Equipment to Overcome the Problems of Impedance and Scale Mismatch

The emergence of new materials (nanowires, nanotubes, graphene tapes, and thin films) and devices with nanoscale dimensions give rise to the necessity for developing dedicated techniques that will allow their electrical characterization at high-frequency range. In this article, two possible views have been highlighted to tackle the issue of the measurement of high-impedance nanoscale devices. The first solution is based on the integration of a high-impedance reflectometer and a nanoscale device on the same chip. The microwave impedance of a single CNT has been successfully measured up to 6 GHz using this technique. The second solution consists of inserting an adjustable microwave interferometer between a traditional VNA and the high-impedance device. The interferometer allows adjustment of the impedance to be measured to the highest measurement sensitivity of the measurement system. In particular, capacitances down to 0.35 fF have been measured with an error estimated to be less than 10% using the interferometric technique combined with a scanning microwave microscope. These proofs of concept on one-port nanodevices open the route towards the case of two-port active devices with high impedance. Advances in the manufacturing of next-generation nanodevices will depend on our ability to measure electrical properties and performance characteristics accurately and reproducibly at the nanoscale regime over a broad frequency range.

Peroxynitrite activity of hemin-functionalized reduced graphene oxide

Conducting interfaces modified with reduced graphene oxide (rGO) have shown improved electrochemical response for different analytes. The efficient formation of functionalized rGO based materials is thus of current interest for the development of sensitive and selective biosensors. Herein, we report a simple and environmentally friendly method for the formation of a hemin-functionalized rGO hybrid nanomaterial that exhibits remarkable sensitivity to peroxynitrite (ONOO(-)) in solution. The hemin-functionalized rGO hybrid nanomaterial was formed by mixing an aqueous solution of graphene oxide (GO) with hemin and sonicating the suspension for 5 h at room temperature. In addition to playing a key role in biochemical and electrocatalytic reactions, hemin has been proven to be a good reducing agent for GO. The sensitivity of the peroxynitrite sensor is ≈7.5 ± 1.5 nA mM(-1) with a detection limit of 5 ± 1.5 nM.