Current Issue : January - March Volume : 2020 Issue Number : 1 Articles : 5 Articles
As one of the highest mobility semiconductor materials, carbon nanotubes (CNTs) have\nbeen extensively studied for use in field effect transistors (FETs). To fabricate surround-gate FETs--\nwhich offer the best switching performance--deposition of conformal, weakly-interacting dielectric\nlayers is necessary. This is challenging due to the chemically inert surface of CNTs and a lack of\nnucleation sites--especially for defect-free CNTs. As a result, a technique that enables integration of\nuniform high-k dielectrics, while preserving the CNTâ??s exceptional properties is required. In this\nwork, we show a method that enables conformal atomic layer deposition (ALD) of high-k dielectrics\non defect-free CNTs. By depositing a thin Ti metal film, followed by oxidation to TiO2 under ambient\nconditions, a nucleation layer is formed for subsequent ALD deposition of Al2O3. The technique is\neasy to implement and is VLSI-compatible. We show that the ALD coatings are uniform, continuous\nand conformal, and Raman spectroscopy reveals that the technique does not induce defects in the\nCNT. The resulting bilayer TiO2/Al2O3 thin-film shows an improved dielectric constant of 21.7 and an\nequivalent oxide thickness of 2.7 nm. The electrical properties of back-gated and top-gated devices\nfabricated using this method are presented....
We present in this paper a fully integrated low-noise high common-mode rejection ratio\n(CMRR) logarithmic programmable gain amplifier (LPGA) and chopped LPGA circuits for EEG\nacquisition systems. The proposed LPGA is based on a rail-to-rail true logarithmic amplifier (TLA)\nstage. The high CMRR achieved in this work is a result of cascading three amplification stages\nto construct the LPGA in addition to the lower common-mode gain of the proposed logarithmic\namplification topology. In addition, the 1/f noise and the inherent DC offset voltage of the input\ntransistors are reduced using a chopper stabilization technique. The CMOS 180 nm standard\ntechnology is used to implement the circuits. Experimental results for the integrated LPGA show a\nCMRR of 140 dB, a differential gain of 37 dB, an input-referred noise of 0.754 microVrms, a 189 microW power\nconsumption from 1.8 V power supply and occupies an active area of 0.4 mm2....
Titanium nitride (TiN) has mechanical and electrical characteristics applicable for very\nlarge scale integration (VLSI) and discrete electronic devices. This study assessed the effect of\nhydrogen on sputtering growth of TiN on ceramic substrates. Although ceramic substrate is used\nin discrete device applications due to its insulating property, ceramic is also porous and contains\noxygen and water vapor gases, which can be incorporated into TiN films during growth. In addition,\ndiscrete devices are usually packaged in glass sealing at 700 DegreeC, and reaction with the trapped gases\ncan significantly degrade the quality of the TiN film. In order to evaluate ways to minimize the\neffects of these gases on TiN, hydrogen gas was introduced during sputtering growth. The main\nhypothesis was that the hydrogen gas would react with oxygen to lower the oxygen density in the\nvacuum chamber, which would suppress the effects of the trapped gases in the ceramic and ultimately\nimprove the quality of the TiN film. Improvements in TiN quality were confirmed by X-ray diffraction\n(XRD), energy dispersive spectroscopy (EDS), and resistance measurements. During the glass-sealing\nprocess,N2-purging at 400 DegreeC was effective at keeping the TiN in a low resistance state. These results\nshow that introducing hydrogen gas during sputtering growth could solve the problems caused by\nceramic substrates....
High-performance packet classification algorithms have been widely studied during the\npast decade. Bit-Vector-based algorithms proposed for FPGA can achieve very high throughput by\ndecomposing rules delicately. However, the relatively large memory resources consumption severely\nhinders applications of the algorithms extensively. It is noteworthy that, in the Bit-Vector-based\nalgorithms, stringent memory resources in FPGA are wasted to store relatively plenty of useless\nwildcards in the rules. We thus present a memory-optimized packet classification scheme named\nWeeBV to eliminate the memory occupied by the wildcards. WeeBV consists of a heterogeneous\ntwo-dimensional lookup pipeline and an optimized heuristic algorithm for searching all the wildcard\npositions that can be removed. It can achieve a significant reduction in memory resources without\ncompromising the high throughput of the original Bit-Vector-based algorithms. We implementWeeBV\nand evaluate its performance by simulation and FPGA prototype. Experimental results show that\nour approach can save 37% and 41% memory consumption on average for synthetic 5-tuple rules and\nOpenFlow rules respectively....
In the present investigation, a nitrogen-doped multilayer homoepitaxial single crystal\ndiamond is synthesized on a high-pressure high temperature (HPHT) Ib-type diamond substrate\nusing the microwave plasma chemical vapor deposition (MPCVD) method. When 0.15 sccm of\nnitrogen was added in the gas phase, the growth rate of the doped layer was about 1.7 times\nthat of the buffer layer, and large conical and pyramidal features are formed on the surface of the\nsample. Raman mapping and photoluminescence imaging of the polished cross sectional slice shows\na broadband emission, with a characteristic zero phonon line (ZPL) at 575 nm in the doped layers,\nand large compressive stress was formed in the nitrogen-doped layers. X-ray topography shows\nthat the defects at the interface can induce dislocation. The pyramid feature is formed at the defect,\nand more nitrogen-related defects are formed in the pyramid region. Thin nitrogen-doped multilayers\nwere successfully prepared, and the thickness of the nitrogen-doped and buffer layers was about\n650 nm each. The indentation measurements reveal that the thin nitrogen-doped multilayers are\nultra-tough (at least ~22 MPa m1/2), compared to the Ib-type HPHT seed substrate (~8 MPa m1/2) and\nthe unintentionally doped chemical vapor deposition (CVD) single crystal diamond (~14 MPa m1/2)....
Loading....