Opportunistic Networks: Present Scenario- A Mirror Review

Opportunistic Network is form of Delay Tolerant Network (DTN) and regarded as extension to Mobile Ad Hoc Network. OPPNETS are designed to operate especially in those environments which are surrounded by various issues like- High Error Rate, Intermittent Connectivity, High Delay and no defined route between source to destination node. OPPNETS works on the principle of “Store-and-Forward” mechanism as intermediate nodes perform the task of routing from node to node. The intermediate nodes store the messages in their memory until the suitable node is not located in communication range to transfer the message to the destination. OPPNETs suffer from various issues like High Delay, Energy Efficiency of Nodes, Security, High Error Rate and High Latency. The aim of this research paper is to overview various routing protocols available till date for OPPNETs and classify the protocols in terms of their performance. The paper also gives quick review of various Mobility Models and Simulation tools available for OPPNETs simulation

Study of electron traps associated with oxygen superlattices in n‐type silicon

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Garbage Monitoring And Management Using Deep Learning

Rapid urbanisation and population growth have led to an unprecedented increase in waste generation. In addition to this, increasing tourism has also increased the challenge of maintaining coastal areas. Inefficient and inadequate waste management practices pose significant environmental and health hazards to both humans and wildlife. Through deep learning and computer vision techniques, the garbage can be identified and its location can be extracted directly from the images. Videos are collected using UAVs. Auto generation of waste reports and additional services like chat-bots are also implemented. Furthermore, the system implements OR tools using which the routes of garbage collector vehicles is optimised. By minimising travel distances and maximising cleanup efficiency, the system reduces operational costs and enhances the overall effectiveness of beach cleanup initiatives. Predominant spots of garbage are analysed and the nearest dustbins are mapped along with the route to reach the dustbin. The garbage detection model gave a mAP of 0.845. The silhouette score of clustering was 70.1% for chameleon and 99.02% for k means. All of the above mentioned modules were integrated and presented on the user interface of the application developed

Electron microscopy of quantum dots

This brief review describes the different types of semiconductor quantum dost systems, their main applications and which types of microscopy methods are used to characterize them. Emphasis is put on the need for a comprehensive investigation of their size distribution, microstructure, chemical composition, strain state and electronic properties, all of which influence the optical properties and can be measured by different types of imaging, diffraction and spectroscopy methods in an electron microscope

Quasi 2D Si-O Superlattices for Future Nanoelectronic Applications

Graphite-like 2D nanolattices of dielectrics andsemiconductors with enhanced anisotropic electronic properties are goodcandidates to pave the way to the ultimate scaling and performances of future nanoelectronic devices. Graphene, the most studied representativeof the 2D graphitic materials, has overshadowed research on other potential quasi-2D nanolattices with totally unexplored physical properties. For instance, 3D materials, in which strong anisotropic is introduced inthe band structure, could potentially lead to enhanced mobility and display quasi-2D properties. Such structures could be induced in Si and Ge lattices, by epitaxial layering with non-semiconducting monolayers, so called superlattices. In such a case, the band structure and the density of states could be strongly modified reducing in-plane effective mass while inhibiting the transport perpendicular to the layers. This could reduce gate leakage and carrier scattering, thus maintaining high mobility at low equivalent oxide thickness. A first goal of the PhD project is to develop processes for the fabrication of Si/O, Si/N, Si/C and Si/S superlattices. The fabrication of such superlatticesrequires precise control at the (sub)-monolayer level to maintain the epitaxial Si structure. The approach is therefore based on atomically controlled processing by CVD. Self-limiting chemisorption reactions are used to control the amount of O, N, C, and S in the superlattices. This technique has already been used for epitaxial layering of Si and N. Structural characterization of these superlattices is done using Transmission Electron Microscopy (TEM). X-ray Photoelectron Spectroscopy (XPS) is usedfor having the bonding information at the interfaces and Secondary Ion Mass Spectroscopy (SIMS) is used to determine the atom density at the interface. Understanding of the deposition process will contribute to the development of superlattices with optimal transport properties. A second goal of the PhD project is the study of the carrier transport properties of these materials. Especially the carrier mobility, current carrier capability and the band gap of these materials are important parameters in this respect. MOS-type test structures including simple transistors will be made on the engineered Si superlattices to evaluate the electrical properties of these materials, such as mobility and gate leakage. Low temperature processing will be needed for the gate stackand source/drain contact formation in order not disturb the nanolatticestructure. The results of the electrical tests will provide insight in the basic properties of these materials and allow benchmarking them against other candidates for advanced nano-electronic applications, such as graphene and high mobility channel materials (III-V).status: publishe

A deep-level transient spectroscopy study of p-type silicon Schottky barriers containing a Si-O superlattice

The presence of deep levels in a silicon-oxygen (Si-O) superlattice (SL) deposited on p-type silicon substrates has been investigated by deep-level transient spectroscopy (DLTS) on thermally evaporated Cr Schottky barriers (SBs). The SLs have been fabricated with different thicknesses of the silicon interlayers, formed by chemical vapor deposition. It is shown that a broad band of hole traps is present near the surface of the SB, which is associated with the SL. In addition, the activation energy corresponding with the peak maximum shifts to higher values with respect to the valence band and gives rise to a higher trap concentration with increasing silicon interlayer thickness. It is proposed that these states are associated with the structural defects found in similar SL structures, that is, with the epitaxial quality and not with the SiO bonds in the atomic layers. The change in the DLT-spectra with silicon thickness could be related with the transformation of the structural defects from small self-interstitial clusters to stacking faults

Comparison between Si/SiO2 mid-gap interface states and deep levels associated with silicon-oxygen superlattices in p-type silicon

Copyright © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim In this paper, the deep levels found by deep-level transient spectroscopy in Si-O superlattices on p-type silicon substrates are compared with the band of near mid-gap hole traps typically observed at the Si/SiO2 interface. In addition, the impact of a post-deposition Forming Gas Annealing is investigated. A large similarity between the two material systems is reported, which indicates that similar silicon-oxygen bonds may be responsible for the deep hole traps.(© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim).status: publishe

Deep levels in silicon-oxygen superlattices

This work reports on the deep levels observed in Pt/Al2O3/p-type Si metal-oxide-semiconductor capacitors containing a silicon–oxygen superlattice (SL) by deep-level transient spectroscopy. It is shown that the presence of the SL gives rise to a broad band of hole traps occurring around the silicon mid gap, which is absent in reference samples with a silicon epitaxial layer. In addition, the density of states of the deep layers roughly scales with the number of SL periods for the as-deposited samples. Annealing in a forming gas atmosphere reduces the maximum concentration significantly, while the peak energy position shifts from close-to mid-gap towards the valence band edge. Based on the flat-band voltage shift of the Capacitance–Voltage characteristics it is inferred that positive charge is introduced by the oxygen atomic layers in the SL, indicating the donor nature of the underlying hole traps. In some cases, a minor peak associated with P b dangling bond centers at the Si/SiO2 interface has been observed as well.status: publishe