1,721,116 research outputs found
High quality Schottky contacts for limiting leakage currents in Ge-based Schottky barrier MOSFETs
Full text linkSchottky barrier (SB) Ge channel MOSFETs suffer from high drain-body leakage at the required elevated substrate doping concentrations to suppress source-drain leakage. Here we show that electrodeposited Ni-Ge and NiGe/Ge Schottky diodes on highly doped Ge show low off current, which might make them suitable for SB p-MOSFETs. The Schottky diodes showed rectification of up to 5 orders in magnitude. At low forward biases the overlap of the forward current density curves for the as deposited Ni/n-Ge and NiGe/n-Ge Schottky diodes indicates Fermi-level pinning in the Ge band gap. The SB height for electrons remains virtually constant at 0.52 eV (indicating a hole barrier height of 0.14 eV) under various annealing temperatures. The series resistance decreases with increasing annealing temperature in agreement with four point probe measurements indicating the lower specific resistance of NiGe as compared to Ni, which is crucial for high drive current in SB p-MOSFETs. We show by numerical simulation that by incorporating such high quality Schottky diodes in the source/drain of a Ge channel PMOS, highly doped substrate could be used to minimize the subthreshold source to drain leakage current
High-quality NiGe/Ge diodes for Schottky barrier MOSFETs
No full textSchottky barrier (SB) Ge channel MOSFETs suffer from high drain-body leakage at the required elevated substrate doping concentrations to suppress source–drain leakage. Here, we show that electrodeposited Ni–Ge and NiGe/Ge Schottky diodes on highly doped Ge show low off current, which might make them suitable for SB-MOSFETs. The Schottky diodes showed rectification of up to five orders in magnitude. At low forward biases, the overlap of the forward current density curves for the as-deposited Ni/n-Ge and NiGe/n-Ge Schottky diodes indicates Fermi-level pinning in the Ge bandgap. The SB height for electrons remains virtually constant at ∼0.52 eV (indicating a hole barrier height of ∼0.14 eV) under various annealing temperatures. The series resistance decreases with increasing annealing temperature in agreement with four-point probe measurements indicating the lower specific resistance of NiGe as compared with Ni, which is crucial for high drive current in SB-MOSFETs. We show by numerical simulation that by incorporating such high-quality Schottky diodes in the source/drain of a Ge channel PMOS, highly doped substrate could be used to minimize the subthreshold source to drain leakage current
Hotspot-mediated ultrafast nonlinear control of multifrequency plasmonic nanoantennas
No full textPlasmonic devices have a unique ability to concentrate and convert optical energy into a small volume. There is a tremendous interest in achieving active control of plasmon resonances, which would enable switchable hotspots for applications such as surface-enhanced spectroscopy and single molecule emission. The small footprint and strong-field confinement of plasmonic nanoantennas also holds great potential for achieving transistor-type devices for nanoscale-integrated circuits. To achieve such a functionality, new methods for nonlinear modulation are required, which are able to precisely tune the nonlinear interactions between resonant antenna elements. Here we demonstrate that resonant pumping of a nonlinear medium in a plasmonic hotspot produces an efficient transfer of optical Kerr nonlinearity between different elements of a multifrequency antenna. By spatially and spectrally separating excitation and readout, isolation of the hotspot-mediated ultrafast Kerr nonlinearity from slower, thermal effects is achieved
Spin-polarized tunneling, magnetoresistance and interfacial effects in ferromagnetic junctions
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Semi-insulating silicon by deep level doping for radio frequency applications
No full textDeep level Mn doping by ion implantation and RTA have been used for the first time to make very high resistivity Czochralski silicon substrates up to 10 kΩcm and on the average, resistivity increased nearly ten-fold. Interesting features, like trapping by end-of-range defects, out-diffusion and partial activation of Mn dopant atoms were observed
Comprehensive analysis of radiative cooling enabled thermoelectric energy harvesting
No full textThe market for Internet-of-Things (IoT) with integrated wireless sensor networks (WSN) is expanding at a rate never seen before. The thriving of IoT also brings an unprecedented demand for sustainable micro-Watt-scale power supplies. Radiative cooling (RC) can provide a continuous temperature difference which can be converted by a thermoelectric generator (TEG) into electrical power. This novel combination of radiative cooling with TEG expands the category of sustainable energy sources for energy harvesting. However, the further application of RC-TEG requires a holistic investigation of its RC-TEG performance which is dependent on many different parameters. Using 3D finite element method simulation, this works provides a comprehensive analysis of the concept of RC-TEG by investigating the impact of radiative cooler properties, TEG parameters, and environmental conditions, to provide a full picture of the performance of RC-TEG devices. The capability of RC-TEG to provide continuous power supply is tested using real-time environmental data from both Singapore and London on two different days of the year, demonstrating continuous power supply sufficient for a wide range of physical devices
High quality NiGe/Ge diodes for Schottky barrier MOSFETs
No full textSchottky barrier (SB) Ge channel MOSFETs suffer from high drain/body leakage at the required elevated substrate doping concentrations. Here we show that electrodeposited Ni-Ge and NiGe/Ge Schottky diodes on highly doped Ge show very low off current, which might make them suitable for SB-MOSFETs. Diodes were fabricated by electrodeposition of Ni on n-type Ge having a resistivity of 0.005-0.02 ohm-cm. Germanidation was performed by annealing the samples in an inert atmosphere at temperatures up to 500° C. X-ray diffraction analysis and the scanning electron microscope images confirm the existence of only polycrystalline NiGe phase at the various annealing temperatures. The current density vs. voltage curves of both of the as deposited Ni/n-Ge and the annealed NiGe/n-Ge diodes show the forward current density being ~5 orders in magnitude higher than the reverse current density at 1 volt bias. Moreover, at low forward biases, there is a sharp overlap of the forward current density for the as deposited Ni/n-Ge and NiGe/n-Ge Schottky diodes. This SB height remains virtually constant at 0.52 eV under annealing indicating consistent Fermi pinning in the Ge band gap. The series resistance decreases with annealing in agreement with four point probe measurements indicating the lower specific resistance of NiGe as compared to Ni, which is crucial for high drive current in SB-MOSFETs. The experimental data of the diodes are used to calibrate numerical simulations of the SB-MOSFETs
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