258 research outputs found
Monte Carlo simulation of implant free InGaAs MOSFET
No full textThe performance potential of n-type implant free In0.25Ga0.75As MOSFETs with high-κ dielectric is investigated using ensemble Monte Carlo device simulations. The implant free MOSFET concept takes advantage of the high mobility in III-V materials to allow operation at very high speed and low power. A 100 nm gate length implant free In0.25Ga0.75As MOSFET with a layer structure derived from heterojunction transistors may deliver a drive current of 1800 A/m and transconductance up to 1342 mS/mm. This implant free transistor is then scaled in the both lateral and vertical dimensions to gate lengths of 70 and 50 nm. The scaled devices exhibit continuous improvement in the drive current up to 2600 A/m and 3259 A/m and transconductance of 2076 mS/mm and 3192 mS/mm, respectively. This demonstrates the excellent scaling potential of the implant free MOSFET concept
Multidimensional partitioning and bi-partitioning : analysis and application to gene expression datasets
No full textEigenvectors and, more generally, singular vectors, have proved to be useful tools for data mining and dimension reduction. Spectral clustering and reordering algorithms have been designed and implemented in many disciplines, and they can be motivated from several dierent standpoints. Here we give a general, unied, derivation from an applied linear algebra perspective. We use a variational approach that has the benet of (a) naturally introducing an appropriate scaling, (b) allowing for a solution in any desired dimension, and (c) dealing with both the clustering and bi-clustering issues in the same framework. The motivation and analysis is then backed up with examples involving two large data sets from modern, high-throughput, experimental cell biology. Here, the objects of interest are genes and tissue samples, and the experimental data represents gene activity. We show that looking beyond the dominant, or Fiedler, direction reveals important information
Effect of impact ionization in scaled pHEMTs
No full textThe effect of impact ionization on pseudomorphic high electron mobility transistors is studied using Monte Carlo simulations when these devices are scaled into deep decanano dimensions. The scaling of devices with gate lengths of 120, 90, 70, 50 and 30 nm has been performed in both lateral and vertical directions. The impact ionization is treated as an additional scattering mechanism in the Monte Carlo module. The critical drain voltage, at which device characteristics begin to indicate breakdown, decreases as the gate voltage is lowered. Similarly, the breakdown drain voltage is also found to decrease during the scaling process
Enhancement-mode GaAs MOSFETs with an In0.3 Ga0.7As channel, a mobility of over 5000 cm2/V ·s, and transconductance of over 475 μS/μm
No full textWe present metal-gate high-k-dielectric enhancement-mode (e-mode) III-V MOSFETs with the highest reported effective mobility and transconductance to date. The devices employ a GaGdO high-k (k = 20) gate stack, a Pt gate, and a delta-doped InGaAs/AlGaAs/GaAs hetero-structure. Typical 1-mum gate length device figures of merit are given as follows: saturation drive current, Id,sat = 407 muA/mum; threshold voltage, Vt = +0.26 V; maximum extrinsic transconductance, gm = 477 muS/mum (the highest reported to date for a III-V MOSFET); gate leakage current, Ig = 30 pA; subthreshold swing, S = 102 mV/dec; on resistance, Ron = 1920 Omega-mum; Ion/Ioff ratio = 6.3 x 104; and output conductance, gd = 11 mS/mm. A peak electron mobility of 5230 cm2/V. s was extracted from low-drain-bias measurements of 20 mum long-channel devices, which, to the authors' best knowledge, is the highest mobility extracted from any e-mode MOSFET. These transport and device data are highly encouraging for future high-performance n-channel complementary metal-oxide-semiconductor solutions based on III-V MOSFETs
Epigenetic downregulation of human disabled homolog 2 switches TGF-beta from a tumor suppressor to a tumor promoter
No full textThe cytokine TGF-beta acts as a tumor suppressor in normal epithelial cells and during the early stages of tumorigenesis. During malignant progression, cancer cells can switch their response to TGF-beta and use this cytokine as a potent oncogenic factor; however, the mechanistic basis for this is poorly understood. Here we demonstrate that downregulation of disabled homolog 2 (DAB2) gene expression via promoter methylation frequently occurs in human squamous cell carcinomas (SCCs) and acts as an independent predictor of metastasis and poor prognosis. Retrospective microarray analysis in an independent data set indicated that low levels of DAB2 and high levels of TGFB2 expression correlate with poor prognosis. Immunohistochemistry, reexpression, genetic knockout, and RNAi silencing studies demonstrated that downregulation of DAB2 expression modulated the TGF-beta/Smad pathway. Simultaneously, DAB2 down-regulation abrogated TGF-beta tumor suppressor function, while enabling TGF-beta tumor-promoting activities. Downregulation of DAB2 blocked TGF-beta-mediated inhibition of cell proliferation and migration and enabled TGF-beta to promote cell motility, anchorage-independent growth, and tumor growth in vivo. Our data indicate that DAB2 acts as a tumor suppressor by dictating tumor cell TGF-beta responses, identify a biomarker for SCC progression, and suggest a means to stratify patients with advanced SCC who may benefit clinically from anti-TGF-beta therapies
Analysis of the singular value decomposition as a tool for processing microarray expression data
No full textWe give two informative derivations of a spectral algorithm for clustering and partitioning a bi-partite graph. In the first case we begin with a discrete optimization problem that relaxes into a tractable continuous analogue. In the second case we use the power method to derive an iterative interpretation of the algorithm. Both versions reveal a natural approach for re-scaling the edge weights and help to explain the performance of the algorithm in the presence of outliers. Our motivation for this work is in the analysis of microarray data from bioinformatics, and we give some numerical results for a publicly available acute leukemia data set
DNA meets the SVD
No full textThis paper introduces an important area of computational cell biology where complex, publicly available genomic data is being examined by linear algebra methods, with the aim of revealing biological and medical insights
High mobility III-V MOSFETs for RF and digital applications
No full textDevelopments over the last 15 years in the areas of materials and devices have finally delivered competitive III-V MOSFETs with high mobility channels. This paper briefly reviews the above developments, discusses properties of the GdGaO/Ga2O3 MOS systems, presents GaAs MOSFET DC and RF data, and concludes with an outlook for high indium content channel MOSFETs. GaAs based MOSFETs are potentially suitable for RF power amplification, switching, and front-end integration in mobile and wireless applications while MOSFETs with high indium content channels are of interest for future CMOS applications
Impact of interface state trap density on the performance characteristics of different III–V MOSFET architectures
No full textThe effect of interface state trap density, D(it), on the current-voltage characteristics of four recently proposed III-V MOSFET architectures: a surface channel device, a flat-band implant-free HEMT-like device with delta-doping below the channel, a buried channel design with delta-doping, and implant-free quantum-well HEMT-like structure with no delta-doping, has been investigated using TCAD simulation tools. We have developed a methodology to include arbitrary energy distributions of interface states into the input simulation decks and analysed their impact on subthreshold characteristics and drive current. The distributions of interface states having high density tails that extend to the conduction band can significantly impact the subthreshold performance in both the surface channel design and the implant-free quantum-well HEMT-like structure with no delta-doping. Furthermore, the same distributions have little or no impact on the performance of both flat-band implant-free and buried channel architectures which operate around the midgap. (C) 2009 Elsevier Ltd. All rights reserved.This work is funded by FP7 Project No. 214579 DUALLOGIC andEPSRC Grant EP/F002610/1 ‘‘III–V MOSFETs for ultimate CMOS”
1 μm gate length, In<sub>0.75</sub>Ga<sub>0.25</sub>As channel, thin body n-MOSFET on InP substrate with transconductance of 737μS/μm
No full textThe first demonstration of implant-free, flatband-mode In<sub>0.75</sub>Ga<sub>0.25</sub>As
channel n-MOSFETs is reported. These 1 μm gate length
MOSFETs, fabricated on a structure with average mobility of
7720 cm<sup>2</sup>/Vs and sheet carrier concentration of 3.3×10<sup>12</sup> cm<sup>-22</sup>,
utilise a Pt gate, a high-k dielectric (k≈20), and a δ-doped
InAlAs/InGaAs/InAlAs heterostructure. The devices have a typical
maximum drive current (I<sub>d,sat</sub>) of 933 μA/μm, extrinsic transconductance
(g<sub>m</sub>) of 737 μS/μm, gate leakage (I<sub>g</sub>) of 40 pA, and on-resistance
(R<sub>on</sub>) of 555 Ωμm. The g<sub>m</sub> and R<sub>on</sub> figures of merit are the
best reported to date for any III-V MOSFET
- …
