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We present a physical compact model for the calculation of the capacitance including a physics based model for the calculation of the charge centroid for III-V FETs. We have used Fermi-Dirac statistics considering two energy subbands obtained from analytical Schrödinger-Poisson solution of charge. The model is validated with data from numerical device simulations and shows excellent match.
The changes in dc characteristics of AlGaN/GaN HEMT after ICP-CVD silicon nitride (SiNx) passivation using two different recipes were investigated. Room temperature Raman analysis was performed to determine the stress state of the AlGaN layer after SiNx passivation. The changes in the stress state of the device after passivation was correlated with the shift in threshold voltage and changes in drain...
200 nm thick films of gallium nitride were grown on sapphire substrate using molecular beam epitaxy. Gold nanoparticles were fabricated on the grown films by thermal evaporation followed by annealing. Aluminium nanostructures were fabricated on another set of films using nanosphere lithography. Interdigited electrodes were fabricated using standard lithography to form metal-semiconductor-metal photodetectors...
Experimental observations of simultaneous existence of fast and slow trap states in AlGaN/GaN HEMTs are presented here. The presence of traps with time constants (0.1 ms ∼ 0.1 s) and activation energies (0.3 eV∼0.54 eV) was detected from transconductance dispersion and admittance curves. These fast traps may assist the high gate leakage currents in AlGaN/GaN HEMTs. The slower traps having the time...
A physics-based, charge-based model for P-type Gaussian doped DG MOSFET is presented in this work. The developed model is also applicable to the investigation of the impact of channel material on the performance of p-type DG MOSFET. The reliability issues of the p-type MOSFET have also been demonstrated using both developed analytical model and simulated results. The performance degradation due to...
We have investigated the influence of the reverse transfer conductance Rgd to extract the small signal parameters of GaN high electron mobility transistors (HEMTs) at microwave frequencies. In this paper a simplified method for extracting the small-signal equivalent circuit elements of HEMTs by means of measurements of scattering parameters only is presented. We have calculated the improvement in...
In this paper, we propose a novel methodology of real time dynamic tilt monitoring through the designed and developed Fiber Bragg Grating Tilt Meter (FBGTM). Based on the volumetric water pressure exerted from inside the chamber on the diaphragm over which the FBG sensor is bonded, the tilt angle of FBGTM can be estimated. An inclination platform is constructed to test the designed FBGTM in conjunction...
Hybrid inorganic/organic Cd-doped ZnO nanostructures called CZO nanohybrids were electrochemically synthesized on Ga-doped ZnO/Si. The CZO nanohybrids comprise alternating layers of organic surfactant and CZO inorganic phase. These lamellar structured nanohybrids were found to be c-axis oriented, perpendicular to the substrate with good crystallinity. During photoluminescence measurement, a strong...
Two-phase nanocomposites comprised of Zn1−xNixO/NiO (0.05 ≤ x ≤ 0.3) were grown by using sol-gel process with hydrated metal acetates as precursors. Thermal decomposition of the co-precipitated oxalate α-ZnNi(C2O4) yields wurtzite h.c.p. Zn1−xNixO and f.c.c. NiO together. The X-band electron spin resonance spectra provide the signatures of anisotropic spin interactions with long-range magnetic ordering...
This paper presents a two-dimensional (2D) analytical model for threshold voltage of fully depleted graded-channel silicon-on-insulator (SOI) MOSFETs. The two-dimensional Poisson's equation is solved in different channel regions with parabolic approximation by using suitable boundary conditions. The effect of different device parameters on device performance has been studied. Results confirmed that...
Plasmonic nanostructures in chiral geometries are suitable candidates for various device applications pertaining to optical polarization. These devices can show large chiro-optical effects, implying a strongly differential response to right and left circularly polarized light. In general, three-dimensional plasmonic structures show larger optical activity, but are typically not suitable for wafer-scale...
In the present study, GaN nanowall network (NWN) structures are grown using rf-plasma assisted molecular beam epitaxy (PA-MBE) system under highly nitrogen rich conditions over nitrided and bare c-plane sapphire substrates. Nitridation is carried out prior to growth for two of the samples and its effect on the crystal quality of the resultant nanowall structure is studied and compared with the same...
In this paper, the influence of gate-source and drain-source bias on the bias-stress stability and lifetime of pentacene-based low-voltage (−3 V) organic thin-film transistors (TFTs) built on plastic substrate has been investigated. The 10%-current-decay lifetime is used for analyzing the influence of applied bias on the bias-stress stability of TFTs, and to compare various biasing conditions. Our...
ZnO nanoparticles (ZNPs) were synthesized by wet chemical method using poly vinyl alcohol (PVA) templates. Uniform growth, high yield and excellent optical properties were observed in ZNPs synthesized under pulsed microwave irradiation (PMW). Moreover the dangling bonds of ZNPs prepared under PMW were passivated more effectively than in samples prepared without it. Strong UV emission peaks at ∼ 360...
In this work, energy band structure in a derivative of the conducting polymer carbazole was analyzed by scanning tunneling microscopy and spectroscopy (STM and STS). The band gap formed by evolved energy bands was found by STS to be of 1.7 eV, which may be compared with the electronic bandgap obtained by the bulk DACz diode, which is 0.59 eV. DACz diodes have a very low turn-on voltage of 0.06 V,...
We have fabricated inkjet-printed 6,13-bis(triisopropylsilylethynyl) (TIPS) pentacene thin-film transistor by optimizing a cross-linked poly-4-vinylphenol (PVP) dielectric on glass substrate. The quality and integrity of the polymer dielectric has been studied for different weight percent of PVP and the poly(melamine-co-formaldehyde) as a cross-linking agent (CLA) in propylene glycol methyl ether...
Deep vertical etching of Si using hydrogen peroxide as oxidant and Au as catalyst has been studied in terms of relative reactant concentrations and catalyst morphology. The concentrations of hydrogen peroxide and hydrofluoric acid are highly important and the ratio of the same can be varied to achieve isotropic to highly anisotropic vertical etching. Catalyst morphology and positioning of the substrate...
AlGaAs/GaAs heterostructures having different thicknesses of AlGaAs layers have been grown by Molecular Beam Epitaxy. Detailed Structural characterization of these structures has been performed and discussed in this report. AlGaAs layer thicknesses have been measured by an electrochemical Capacitance-Voltage profiler by etch profiling and confirmed by field emission scanning electron eicroscopy and...
We propose simple approximate expressions for capacitance and electrostatic force for fixed-fixed beam-based MEMS/NEMS devices subjected to direct electrostatic and fringing field effects. The configuration that are considered for study are fixed-fixed beam and bottom electrode, fixed-fixed beam and side electrode, and a combination of beam, bottom electrode and side electrode. The expressions are...
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