157 research outputs found
Reduction of Parasitic Capacitance in Vertical MOSFETs by Spacer Local Oxidation
No full textApplication of double gate or surround-gate vertical metal oxide semiconductor field effect transistors (MOSFETs) is hindered by the parasitic overlap capacitance associated with their oayout, which is considerably larger than for a lateral MOSFET on the same technology node. A simple self-aligned procfess has been developed to reduce the parasitic overlap capacitance in MOSFETs using nitride spacers on the sidewalls of the trench or pillar and a local oxidation. This will result in an oxide layer on all exposed planar surfaces, but no oxide layer on the protected vertical channel area of the pillar. The encroachment of the oxide on the side of the pillar is studied by transmission electron microscopy (TEM)which is used to calibrate the nitride viscosity in the process simulations. Surround gate vertical transistors incorporating the spacer oxidation have been fabricated, and these transistors show the integrity of the process and excellent subthreshold slope and drive current. The reduction in intrinsic capacitance is calculated to be a factor of three. Pillar capacitors with a more advanced process have been fabricated and the total measured capacitance is reduced by a factor of five compared with structures without the spacer oxidation. Device simulations confirm the measured reduction in capacitance
Experimental and theoretical evidences of hysteresis in passive mode-locked quantum dots lasers
No full textWe report experimental evidence of coexistence between passive mode-locking (ML) solutions and laser off state in a monolithic two sections InAs/InGaAs Quantum Dot (QD) semiconductor laser. The considered device has a 0.4 mm long straight absorber and a 2.380 mm long active region characterized by a 2° full taper angle. The active side facet is as cleaved, while the absorber side facet is high reflection coated
Low-head hydropower as a reserve power source for wind power
No full textWind power generation faces intermittency challenges, typically requiring reserve power generation sources burning fossil fuels to maintain reliability of the electricity grid in the event of a decrease in wind. This study proposes an alternative hypothesis: that hydropower turbines installed at low-head dams can provide similar reserve power generation to support wind, thereby avoiding the externalities associated with fossil-fuel plants and conventional hydropower. Low-head dams, common across the United States, are used for flood control, securing municipal water supplies, and providing ample water depth for recreation. As a case study, hydropower potential at 13 such dams along a 150-kilometer reach of the Fox River (Northeastern Illinois, USA) was estimated using a HEC-RAS model calibrated with U.S. Geological Survey data. The output of the model was then analyzed to determine the capacity of the system and gauge its reliability both as a standalone generator and as a component in a coupled wind-hydropower system. Findings revealed that economic, environmental, and regulatory factors all affected the implementation of this low-head hydropower system. The system was found to perform reliably over a five-year time period in spite of significant long-term fluctuations in streamflow, thereby enabling it to offset the short-term variability of wind power. However, combining the low-head hydropower system with wind power limits the reliable output of the entire system to the lowest amount of power generated by the low-head hydropower system, regardless of how much wind power is deployed. The low-head hydropower system's relatively small capacity and inauspicious cost-benefit ratio suggest that this low-head hydropower system would be best suited for local applications rather than grid-scale operations, especially if environmental and regulatory considerations are included.Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2021-05-01The student, Trevor Auth, accepted the attached license on 2019-04-19 at 17:04.The student, Trevor Auth, submitted this Thesis for approval on 2019-04-19 at 17:11.This Thesis was approved for publication on 2019-04-22 at 16:27.DSpace SAF Submission Ingestion Package generated from Vireo submission #13795 on 2019-08-22 at 15:07:35Made available in DSpace on 2019-08-23T20:36:05Z (GMT). No. of bitstreams: 2
AUTH-THESIS-2019.pdf: 4928113 bytes, checksum: 5607561ed5f7181acff3cb7c7d2fb6a9 (MD5)
LICENSE.txt: 4208 bytes, checksum: f30c100a8f0b95b112ebf1a3032c529b (MD5)
Previous issue date: 2019-04-22Embargo set by: Seth Robbins for item 112185
Lift date: 2021-08-23T20:36:18Z
Reason: Author requested U of Illinois access only (OA after 2yrs) in Vireo ETD systemU of I Only Restriction Lifted for Item 112185 on 2021-08-24T09:15:24Z
Transcript-specific expression profiles derived from sequence-based analysis of standard microarrays
No full textBackground: Alternative mRNA processing mechanisms lead to multiple transcripts (i.e. splice isoforms) of a given gene
which may have distinct biological functions. Microarrays like Affymetrix GeneChips measure mRNA expression of genes
using sets of nucleotide probes. Until recently probe sets were not designed for transcript specificity. Nevertheless, the reanalysis of established microarray data using newly defined transcript-specific probe sets may provide information about expression levels of specific transcripts.
Methodology/Principal Findings: In the present study alignment of probe sequences of the Affymetrix microarray HGU133A with Ensembl transcript sequences was performed to define transcript-specific probe sets. Out of a total of 247,965 perfect match probes, 95,008 were designated ‘‘transcript-specific’’, i.e. showing complete sequence alignment, no crosshybridization, and transcript-, not only gene-specificity. These probes were grouped into 7,941 transcript-specific probe sets and 15,619 gene-specific probe sets, respectively. The former were used to differentiate 445 alternative transcripts of 215
genes. For selected transcripts, predicted by this analysis to be differentially expressed in the human kidney, confirmatory real-time RT-PCR experiments were performed. First, the expression of two specific transcripts of the genes PPM1A (PP2CA_HUMAN and P35813) and PLG (PLMN_HUMAN and Q5TEH5) in human kidneys was determined by the transcriptspecific array analysis and confirmed by real-time RT-PCR. Secondly, disease-specific differential expression of single transcripts of PLG and ABCA1 (ABCA1_HUMAN and Q5VYS0_HUMAN) was computed from the available array data sets and confirmed by transcript-specific real-time RT-PCR.
Conclusions: Transcript-specific analysis of microarray experiments can be employed to study gene-regulation on the
transcript level using conventional microarray data. In this study, predictions based on sufficient probe set size and foldchange are confirmed by independent mean
An aging world - growing old in developing countries. The Courier No. 176, July/August 1999
No full text
Frequency- and amplitude- modulated semiconductor laser frequency combs
No full textChip-scale coherent semiconductor light sources generating optical frequency combs currently revolutionize mid-infrared on-chip spectroscopy, near-infrared optical communications and nonlinear microscopy. Their key advantages is the efficient generation of narrow and equidistant spectral lines or laser modes with a fixed phase relationship across a broadband spectral region. An attractive realization of such combs is based on nanostructured semiconductor lasers with semiconductor quantum dots forming their active region. In this thesis, frst, the formation of two types of optical frequency combs in a semiconductor quantum dot laser is presented: in-phase synchronization of the intermode beatings, leading to optical pulses, and the splay-phase synchronization, leading to quasi continuous wave optical output. Both states can be generated on demand in a single semiconductor laser. By varying the laser design and the biasing conditions, frequency- and amplitude-modulated combs can be generated on demand. Second, based on their identifed particular temporal characteristics, a novel technique to determine the sensitivity of semiconductor laser frequency combs to optical feedback, is presented. Results suggest, that amplitude-modulated semiconductor laser frequency combs are less sensitive to optical feedback than frequency-modulated semiconductor laser frequency combs. The developed insights are expected to elevate semiconductor laser frequency combs in current and future integrated photonic circuits in optical communications, where unavoidable optical feedback from downstream active and passive components deteriorates comb stability
- …
