Browsing by Author "Zhang, J"

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Embargo
Effect of point defect injection on diffusion of boron in silicon and silicon–germanium in the presence of carbon
(American Institute of Physics, 2005-06-01) Karunaratne, M. S. A; Willoughby, A F W; Bonar, J M; Zhang, J; Ashburn, P
Boron diffusion in Si and strained SiGe with and without C was studied using point defect injection. Interstitial-, vacancy- and noninjection conditions were achieved by annealing Si capping layers which were either bare, with Si3N4 film or with Si3N4+SiO2 bilayers, respectively. Concentration profiles of B, Ge, and C were obtained using secondary-ion-mass spectrometry and diffusion coefficients of B in each type of matrix were extracted by computer simulation. Under inert annealing, we find that C strongly suppresses B diffusion in SiGe:C, but the effect of C is less strong in Si:C, particularly at high temperatures. In contrast, C only weakly suppresses B diffusion in both Si:C and SiGe:C under interstitial injection. For inert anneal conditions, C reduces the B diffusion coefficient in Si:C by factors of 4.2, 5.9, and 1.9 at 940, 1000, and 1050 °C respectively, whereas for interstitial injection the factors are 2.1, 1.3, and 1.1, respectively. The equivalent factors for SiGe:C are 8.4, 5.9, and 8.0 for inert anneal conditions and 2.2, 3.4, and 1.6 for interstitial injection conditions. The degree of B diffusion suppression achieved in both Si:C and SiGe:C is dependent on the level of C retained during annealing. Diffusion of C is shown to be faster in Si:C and hence less C is retained there after annealing than in SiGe:C. Interstitial injection is shown to strongly enhance C diffusion in both Si:C and SiGe:C and hence decreases the effectiveness of C for B diffusion suppression. These findings illustrate that the retarding effect of C on B diffusion in both Si:C and SiGe:C is strongly reduced when the anneal is carried out under conditions where interstitials are injected from the surface.
Open Access
A geo-spatial database about the eco-environment and its key issues in South Asia
(Taylor & Francis, 2018-07-03) Li, A; Deng, W; Zhao, W; Liu, B; Zhang, J; Kong, B; Nan, X; Bian, J; Koirala, H. L; Gilani, H; Sati, V. P; Gomes, P. I. A; Khanal, N. R
The South Asia has high variability ingeographical features, climate,and landscapes. With the rapid economic development and populationgrowth, the increased pressure on natural resources, land degradation,water crisis, and climate change become the common concerns for thecountries in the region. To get a deep and general idea about the landand water natural resources and environment in South Asia, a knowl-edge database was constructed based on the climatic condition, landuse/cover, water resources, water disasters, and geohazards. The resultspresented a scientific insight regarding the spatio-temporal changingpattern of the eco-environmental components in this region. Riskassessments were performed for thefloods, droughts, and geohazardswhich occurred with a high frequency. In general, the big knowledgedatabase established in this study would be helpful to aid the devel-opment of future policies and programs (like the Belt and RoadInitiative) for environmental issues adaptation in the region, includinginitiatives for regional cooperation and capacity building in naturalresources and environment management
Embargo
Resource management of task oriented distributed sensor networks
(IEEE, 2001-05-06) Zhang, J; Kulasekere, E. C; Premaratne, K; Bauer, P. H
In this paper we provide a foundation for a unified analysis of both the decision fusion and congestion avoidance aspects of a task-oriented distributed sensor network (DSN). Such a framework allows network resource management to be carried out in a manner that is sensitive to the overall objectives of the DSN rather than decoupling them via perhaps simple fairness strategies. The proposed approach associates importance measures related to the degradation and relevance of incoming data lines at each network node. These are then used to carry out intelligent resource management and avoid congestion in a manner which is implicitly related to the decision objectives of the DSN and explicitly related to the resource availability. To achieve this, we propose a 'per-flow' technique that decouples data flow among nodes at different hierarchical levels of the DSN. The resulting framework allows seamless integration of the importance measures providing resource management decisions that are sensitive to the overall DSN objectives.