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131.
基于非选择性外延,自对准注入技术,集电区选择性注入和快速热退火工艺,提出了一种适用于1.5μm BiCMOS集成技术的SiGe HBT器件结构。该结构具有内基区薄,外基区厚,B/E结两侧杂质浓度低,发射极/基极自对准诸优点。利用TSuprem4和Medici进行工艺模拟和电学特性仿真。结果表明,所设计的的SiGe HBT具有良好的电学特性,其最大电流增益为210,当Vce=2.5 V时,截止频率达到65 GHz,验证了器件结构设计的合理性。 相似文献
132.
一种计算卷积码自由距离的快速算法 总被引:1,自引:0,他引:1
本文给出了一种计算卷积码自由距离的快速算法,该算法把遗传算法与模拟退火有机结合并根据随机概率来控制算法的运行,避免了优化迟钝与盲目现象,提出了该算法的收敛质量和速度,模拟结果表明:与已有算法相比,本算法具有更好可靠性,有效性和稳定性。 相似文献
133.
Consider the classical nonparametric regression problem yi = f(ti) + ii = 1,...,n where ti = i/n, and i are i.i.d. zero mean normal with variance 2. The aim is to estimate the true function f which is assumed to belong to the smoothness class described by the Besov space B
pq
q
. These are functions belonging to Lp with derivatives up to order s, in Lp sense. The parameter q controls a further finer degree of smoothness. In a Bayesian setting, a prior on B
pq
q
is chosen following Abramovich, Sapatinas and Silverman (1998). We show that the optimal Bayesian estimator of f is then also a.s. in B
pq
q
if the loss function is chosen to be the Besov norm of B
pq
q
. Because it is impossible to compute this optimal Bayesian estimator analytically, we propose a stochastic algorithm based on an approximation of the Bayesian risk and simulated annealing. Some simulations are presented to show that the algorithm performs well and that the new estimator is competitive when compared to the more standard posterior mean. 相似文献
134.
Henry Berger 《Microelectronic Engineering》1991,10(3-4):259-267
A survey is given of the BOC Group technical research programs, whose purpose is to relate purity in gas processing to ULSI device parameters. Results from the following research programs are presented: how inert gas purity affects the Ti silicide for IGFET metallization; the effects of argon versus nitrogen used in silicon gate oxidation process steps; and preliminary work on a new gas analytical tool, Atmospheric Pressure Ionization Mass Spectrometry (APIMS), which allows measurement of sub ppb impurity levels in processing gases. 相似文献
135.
The residual electrically active defects in(4×10~(12)cm~(-2)(30KeV)+5×10~(12)cm~(-2)(130KeV))si-implanted LEC undoped si-GaAs activated by two-step rapid thermal annealing(RTA)LABELED AS 970℃(9S)+750℃(12S)have been investigated with deep level transient spec-troscopy(DLTS).Two electron traps ET_1(E_c-0.53eV,σ_n=2.3×10~(-16)cm~2)and ET_2(E_c-0.81eV,σ_n=9.7×10(-13)cm~2)are detected.Furthermore,the noticeable variations of trap's con-centration and energy level in the forbidden gap with the depth profile of defects induced by ion im-plantation and RTA process have also been observed.The[As_i·V_(As)·As_(Ga)]and[V_(As)·As_i·V_(Ga)·As_(Ga)]are proposed to be the possible atomic configurations of ET_1 and ET_2,respectively to explaintheir RTA behaviors. 相似文献
136.
Youn Tae Kim Chi Hoon Jun Jong-Tae Baek Hyung Joun Yoo Sang-Koo Chung 《Journal of Electronic Materials》1995,24(10):1413-1417
In this study, we have investigated sensitivities of the ion implanted silicon wafers processed by rapid thermal annealing
(RTA), which can reveal the variation of sheet resistance as a function of annealing temperature as well as implantation parameters.
All the wafers were sequentially implanted by the arsenic or phosphorous implantations at 40, 80, and 100 keV with the dose
level of 1014 to 2 × 1016 ions/cm2. Rapid thermal annealing was carried out for 10 s by the infrared irradiation at a temperature between 850 and 1150°C in
the nitrogen ambient. The activated wafer was characterized by the measurements of the sheet resistance and its uniformity
mapping. The values of sensitivities are determined from the curve fitting of the experimental data to the fitting equation
of correlation between the sheet resistance and process variables. From the sensitivity values and the deviation of sheet
resistance, the optimum process conditions minimizing the effects of straggle in process parameters are obtained. As a result,
a strong dependence of the sensitivity on the process variables, especially annealing temperatures and dose levels is also
found. From the sensitivity analysis of the 10 s RTA process, the optimum values for the implant dose and annealing temperature
are found to be in the range of 1016 ions/cm2 and 1050-1100°C, respectively. The sensitivity analysis of sheet resistance will provide valuable data for accurate activation
process, offering a guideline for dose monitoring and calibration of ion implantation process. 相似文献
137.
Visible photoluminescence (PL) of nanocrystalline silicon (nc-Si) embedded in single crystal CaF2 formed on Si(1 1 1) has been studied and the influence of ex situ rapid thermal annealing (RTA) on the surface morphology and PL spectra has been studied. It has been found that the PL intensity and uniformity was improved by RTA with appropriate temperature and short annealing time. 相似文献
138.
Distributed automated docking of flexible ligands to proteins: Parallel applications of AutoDock 2.4 总被引:17,自引:0,他引:17
Garrett M. Morris David S. Goodsell Ruth Huey Arthur J. Olson 《Journal of computer-aided molecular design》1996,10(4):293-304
Summary AutoDock 2.4 predicts the bound conformations of a small, flexible ligand to a nonflexible macromolecular target of known structure. The technique combines simulated annealing for conformation searching with a rapid grid-based method of energy evaluation based on the AMBER force field. AutoDock has been optimized in performance without sacrificing accuracy; it incorporates many enhancements and additions, including an intuitive interface. We have developed a set of tools for launching and analyzing many independent docking jobs in parallel on a heterogeneous network of UNIX-based workstations. This paper describes the current release, and the results of a suite of diverse test systems. We also present the results of a systematic investigation into the effects of varying simulated-annealing parameters on molecular docking. We show that even for ligands with a large number of degrees of freedom, root-mean-square deviations of less than 1 Å from the crystallographic conformation are obtained for the lowest-energy dockings, although fewer dockings find the crystallographic conformation when there are more degrees of freedom.The AutoDock 2.4 suite is written in ANSI C, and is supplied with Makefiles for the following platforms: Convex, DEC Alpha OSF/1, Hewlett-Packard Precision Architecture, Silicon Graphics, and Sun. The AutoDock suite of programs is freely available to the noncommercial scientific community and to educational establishments. Further information, including additional figures and MPEG animations showing all docked conformations for each test system, can be found at the following URL: http://www.scripps.edu/pub/olson-web/doc/autodock. 相似文献
139.
Taneda A 《Computational Biology and Chemistry》2005,29(2):324-119
In order to predict non-coding RNA genes and functions on the basis of genome sequences, accurate secondary structure prediction is useful. Although single-sequence folding programs such as mfold have been successful, it is of great importance to develop a novel approach for further improvement of the prediction performance. In the present paper, a secondary structure prediction method based on genetic algorithm, Cofolga, is proposed. The program developed performs folding and alignment of two homologous RNAs simultaneously. Cofolga was tested with a dataset composed of 13 tRNAs, seven 5S rRNAs, five RNase P RNAs, and five SRP RNAs; as a result, it turned out that the average prediction accuracies for the tRNAs, 5S rRNAs, RNase P RNAs, and SRP RNAs obtained by Cofolga with an optimal weight factor and default parameters were 83.6, 81.8, 73.5, and 67.7%, respectively. These results were superior to those obtained by a single-sequence folding based on free-energy minimization in which corresponding average prediction accuracies were 52.4, 47.4, 57.7, and 52.3%, respectively. Cofolga has a post-processing in which a single-sequence folding is performed after fixation of a predicted common structure; this post-processing enables Cofolga to predict a structure that is present in one of two RNAs alone. The executable files of Cofolga (for Windows/Unix/Mac) can be obtained by an e-mail request. 相似文献
140.
Giampaolo?Liuzzi Stefano?LucidiEmail author Veronica?Piccialli Antonello?Sotgiu 《Mathematical Programming》2004,101(2):339-364
In this paper we are concerned with the design of a small low-cost, low-field multipolar magnet for Magnetic Resonance Imaging with a high field uniformity. By introducing appropriate variables, the considered design problem is converted into a global optimization one. This latter problem is solved by means of a new derivative free global optimization method which is a distributed multi-start type algorithm controlled by means of a simulated annealing criterion. In particular, the proposed method employs, as local search engine, a derivative free procedure. Under reasonable assumptions, we prove that this local algorithm is attracted by global minimum points. Additionally, we show that the simulated annealing strategy is able to produce a suitable starting point in a finite number of steps with probability one.This work was supported by CNR/MIUR Research Program Metodi e sistemi di supporto alle decisioni, Rome, Italy.Mathematics Subject Classification (1991):65K05, 62K05, 90C56 相似文献