Monte Carlo simulation of silicon-germanium transistors

Self-consistent Monte Carlo simulation studies of n-channel Si/SiGe modulation doped field effect transistors (MODFETs) and silicon-on-insulator lateral bipolar junction transistors (SOI- LBJTs) are reported in this thesis. As a preliminary to the device studies Monte Carlo simulations of electron transport in bulk Si strained as if grown on Si(_0.77)Ge(_0.23) and Si(_0.55)Ge(_0.45) substrates have been carried out at 300 K, for field strengths varied from 10(^4) to 2 x 10(^7) Vm(^-1). The calculations indicate an enhancement of the average electron drift velocity when Si is tensilely strained in the growth plane. The enhancement of electron velocity is more marked at low and intermediate electric fields, while at very high fields the velocity saturates at about the same value as unstrained Si. In addition the ensemble Monte Carlo method has been used to study the transient response to a stepped electric field of electrons in strained and unstrained Si. The calculations suggest that significant velocity overshoots occurs in strained material. Simulations of n-channel Si/Si(_1=z)Ge(_z) MODFETs with Ge fractions of 0.23, 0.25, and 0.45 have been performed. Five depletion mode devices with x = 0.23 and 0.25 were studied. The simulations provide information on the microscopic details of carrier behaviour, including carrier velocity, kinetic energy and carrier density, as a function of position in the device. Detailed time-dependent voltage signal analysis has been carried out to test device response and derive the frequency bandwidth. The simulations predict a current gain cut-off frequency of 60 ± 10 GHz for a device with a gate length of 0.07 /nm and a channel length of 0.25 um. Similar studies of depletion and enhancement mode n-channel Si/Sio.55Geo.45 MODFETs with a gate length of 0.18 /im have been carried out. Cut-off frequencies of 60 ±10 GHz and 90± 10 GHz are predicted for the depletion and enhancement mode devices respectively. A Monte Carlo model has also been devised and used to simulate steady state and transient electron and hole transport in SOI-LBJTs. Four devices have been studied and the effects of junction depth and silicon layer thickness have been investigated. The advantage of the silicon-on-insulator technology SOI device is apparent in terms of higher collector current, current gain, and cut-off frequency obtained in comparison with an all-silicon structure. The simulations suggest that the common-emitter current gain of the most promising SOI-LBJT structure considered could have a cut-off frequency approaching 35 ± 5 GHz

How to Prevent Homelessness When a Bed Is a Home?

While shared-housing programs are a useful strategy for keeping many people from becoming homeless, others need more independent housing in order to climb out of poverty. There is an urgent need for more self-contained social housing in Canada.York's Knowledge Mobilization Unit provides services and funding for faculty, graduate students, and community organizations seeking to maximize the impact of academic research and expertise on public policy, social programming, and professional practice. It is supported by SSHRC and CIHR grants, and by the Office of the Vice-President Research & Innovation. [email protected] www.researchimpact.c

Shared Housing Programs Can Lead People Back into Homelessness

Shared housing does not meet the needs of people who have already been homeless. Many of these people wind up returning to homelessness. Subsidized individual apartments would better meet the needs of those trying to get out of a difficult situation.York's Knowledge Mobilization Unit provides services and funding for faculty, graduate students, and community organizations seeking to maximize the impact of academic research and expertise on public policy, social programming, and professional practice. It is supported by SSHRC and CIHR grants, and by the Office of the Vice-President Research & Innovation. [email protected] www.researchimpact.c

新規金属ハライドの合成とその構造物性相関

京都大学新制・課程博士博士(理学)甲第23023号理博第4700号新制||理||1674(附属図書館)京都大学大学院理学研究科化学専攻(主査)教授 島川 祐一, 教授 寺西 利治, 教授 長谷川 健学位規則第4条第1項該当Doctor of ScienceKyoto UniversityDGA

Influence of Shielding Gas on Aluminum Alloy 5083 in Gas Tungsten Arc Welding

AbstractThe influence of shielding gas parameter was affect to mechanical properties and microstructures of heat-affected zone and fusion zone on gas tungsten arc welding (GTAW) in aluminium alloy AA 5083. The factorial experiment was designed for this research. The factors of AA 5083 weld used in the study types of shielding gas in argon and helium, gas flow rate at 6, 10 and 14 litres per minute. Then the results were using microstructure and vickers hardness test. The result showed that types of shielding gas and gas flow rate interaction hardness at heat-affected zone and fusion zone with a P–value < .05. The factor which was the most effective to the hardness at heat-affected zone and fusion zone was argon with a flow rate of 14 litres per minute at heat-affected zone with 74.27 HV and fusion zone with 68.97 HV. The helium was high thermal conductivity, resulting in a large amount of heat. The grain size was grain growth in larger grain size. This can result in decreased of hardness. Experimental results showed that the argon condition provided smaller grain size, suitable size resulting in higher hardness both in weld metal and HAZ. This research can be used for data on considering on gas tungsten arc welding of aluminium alloy 5083

Transpiration Cooling System in Al-Co Open-celled Foam having PPI of 13

One-dimensional transpiration cooling system in open-celled foam has been conducted experimentally and numerically to investigate the heat transfer characteristics of combined convection and radiation. The Alumina–Cordierite (Al-Co) open-cell foam having porosity of 0.87 and pores per inch (PPI) of 13 was employed. The upper surface of porous plate was heated by the heat flux of incoming radiation (qRx,f) varying from 0.97 - 16.59 kW/m2 whereas air injection velocity (uf) fed into the lower surface was varied from 0.364 - 1.274 m/s, and then uf was converted as Reynolds number (Re). The results show that the temperature efficiency (hT), indicating how close the mean temperature of a porous heat plate to that of inlet air, increased rapidly with the air injection velocity (Re). It was then saturated and had a constant value at Re higher than 30. The conversion efficiency (hC), which was regarded as the ability of porous material in transferring energy by convection after absorbed from heat radiation, decreased slightly with increasing of qRx,f and uf (Re). The numerical predictions also agreed well with experimental data. Keyword: Open-cell foam, Radiation, Transpiration cooling, Reynolds numbe

Accurate fashion and accessories detection for mobile application based on deep learning

Detection and classification have an essential role in the world of e-commerce applications. The recommendation method that is commonly used is based on information text attached to a product. This results in several recommendation errors caused by invalid text information. In this study, we propose the development of a fashion category (FC-YOLOv4) model in providing category recommendations to sellers based on fashion accessory images. The resulting model was then compared to YOLOv3 and YOLOv4 on mobile devices. The dataset we use is a collection of 13,689, which consists of five fashion categories and five accessories' categories. Accuracy and speed analysis were performed by looking at mean average precision (mAP) values, intersection over union (IoU), model size, loading time, average RAM usage, and maximum RAM usage. From the experimental results, an increase in mAP was obtained by 99.84% and an IoU of 88.49 when compared to YOLOv3 and YOLOv4. Based on these results, it can be seen that the models we propose can accurately identify fashion and accessories categories. The main advantage of this paper lies in i) providing a model with a high level of accuracy and ii) the experimental results presented on a smartphone