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Wireless Mobile Ad Hoc Networks are particularly vulnerable due to their fundamental characteristics such as an open medium, dynamic topology, distributed cooperation, and constrained capability. Location information of nodes can be critical in wireless ad hoc networks, especially in those deployed for military purposes. In this paper, we present two Protocols for anonymous routing to prevent location disclosure attacks. The Protocol for Anonymous Routing (PAR) guarantees absolute anonymity, which itself might cause problems as it would become hard to identify malicious and misbehaving nodes. PAR-Enhanced trades off some anonymity to enable detection of malicious and misbehaving nodes. [ABSTRACT FROM AUTHOR]

We propose to use IEEE 802.22 networks as a natural interconnection between energy-constrained networks, such as sensor networks, and the Internet. In this interconnection scenario, we propose Activecast, broadcast designed as a continuation of the IEEE 802.22 broadcast on sensor networks. Activecast effectively transmits a query to all active sensors in the network. Activecast minimizes the number of retransmitted messages while maintaining high reachability. Activecast requires minimum communication overhead, yet performs very well in the presence of various environmental constrains. Activecast can also be integrated to any sleep based sensor protocol, as it does not make any assumptions on the underlying wake up scheduling protocol and wake up times/durations of the sensors. We study the properties of Activecast by analysis and simulations while also considering irregular radio coverage of sensors. [ABSTRACT FROM AUTHOR]

In this paper we present Clustering Protocol for Sensor networks (CPS). Clustering techniques are used by different protocols and applications to increase scalability and reduce delays in sensor networks. Examples include routing protocols, and applications requiring efficient data aggregation. Our approach is based on the Covering Problem that aims at covering an area with minimum number of circular disks. CPS is a lightweight protocol that does not require any neighborhood information and imposes low communication overhead. We present simulation results to show the efficiency of CPS in both ideal cases and randomly distributed networks. Moreover, CPS is scalable with respect to density and network size. [ABSTRACT FROM AUTHOR]

We present Delay-Energy Aware Routing (DEAP) a novel protocol for heterogeneous wireless ad hoc networks. DEAP is a crosslayer scheme that: first, manages adaptively the energy control by controlling the wakeup cycle of sensors based on the experienced packet delay; and second, rout packet in each hoc by distributing the load a group of neighboring nodes. The primary result of DEAP is that it enables a flexible and wide range of tradeoffs between the packet delay and the energy consumption. Therefore, DEAP supports delay sensitive applications of heterogeneous networks that include sensors and actors. DEAP is scalable to the change in network size, node type, node density and topology. DEAP accommodates seamlessly such network changes, including the presence of actors in heterogeneous sensor networks. Indeed, while DEAP does not count on actors, it takes advantage of them, and uses their resources when possible, thus reducing the energy consumption of sensor nodes. Through analysis and simulation evaluations, we show that DEAP improves the packet delay and network lifetime compared to other protocols. [ABSTRACT FROM AUTHOR]

Abstract: Sodium dodecyl sulfate (SDS) self assembles at hydrophobic graphite surfaces forming linear parallel hemicylinders with approximately 5nm spacing between adjacent hemicylinders. In this paper, we report the effect of cosurfactants on the SDS surface micelle structures. It is known from the literature that cosurfactants influence the relaxation times of bulk phase micelles. Specifically, the relaxation times of SDS micelles increase dramatically when cosurfactants, such as non-ionic 1-dodecanol (C12OH) or cationic dodecyl trimethyl ammonium bromide (C12TAB) are added, resulting in the formation of stable micelles. Soft contact AFM imaging was used to determine if these increased relaxation times in bulk solution influence the formation of surface micelle structures at the graphite surface. Surface micelles formed by adsorption from SDS only solutions were significantly different from those surface micelles formed from mixed surfactant solutions. The addition of cosurfactants produced kinks and disrupted the otherwise highly ordered linear hemicylindrical SDS structures observed at graphite surfaces. In one case (SDS/C12OH) swollen surface micelles with a spacing of more than 8nm were observed. Finally, whereas surface micelles form instantaneously from SDS only solutions, the time taken for the equilibrium surface state to be established in the presence of the C12OH cosurfactant was found to be more than 4h. [Copyright &y& Elsevier]

We present Geometric Broadcast for Heterogeneous Sensor Networks (GBS), a novel broadcasting protocol for heterogeneous wireless sensor and actor networks. While broadcasting is a very energy expensive protocol, it is also widely used as a building block for a variety of other network layer protocols. Therefore, reducing the energy consumption by optimizing broadcasting is a major improvement in heterogenous sensor networking. GBS is a distributed algorithm where nodes make local decisions on whether to transmit based on a geometric approach. GBS does not need any neighborhood information and imposes very low communication overhead. GBS is scalable to the change in network size, node type, node density and topology. Furthermore it accommodates seamlessly such network changes, including the presence of actors in heterogeneous sensor networks. Indeed, GBS takes advantage of actor nodes, and uses their resources when possible, thus reducing the energy consumption by sensor nodes. Through simulation evaluations, we show that GBS is very scalable and its performance is improved by the presence of actors. At the best of our knowledge, GBS is the first broadcast protocol designed specifically for heterogeneous sensor and actor networks. [ABSTRACT FROM AUTHOR]

Sensor networks usually operate under very severe energy restrictions. Therefore, sensor communications should consume the minimum possible amount of energy. While broadcasting is a very energy-expensive protocol, it is also widely used as a building block for a variety of other network layer protocols. Therefore, reducing the energy consumption by optimizing broadcasting is a major improvement in sensor networking. In this paper, we propose an optimized Broadcast Protocol for Sensor networks (BPS). The major novelty of BPS is its adaptive-geometric approach that enables considerable reduction of retransmissions by maximizing each hop length. BPS adapts itself and gets the best out of existing radio conditions. In BPS, nodes do not need any neighborhood information, which leads to low communication and memory overhead. We analyze the worst-case scenario for BPS and show that the number of transmissions in such a scenario is a constant multiple of those required in the ideal case. Our simulation results show that BPS is very scalable with respect to network density. BPS is also resilient to transmission errors. [ABSTRACT FROM AUTHOR]

In this paper, we present a novel lightweight protocol for data integrity in wireless sensor networks. Our protocol is based on a leapfrog strategy in which each cluster head verifies if its previous node has preserved the integrity of the packet using the secret key it shares with two hop uptree nodes. The proposed protocol is simple. The analysis and simulation results show that the protocol needs very few header bits, as low as three bits, thus resulting in negligible bandwidth overhead; the protocol poses very low computational overhead, it needs to compute just a hash as compared to multiple complex operations required by any cryptographic implementation for verifying authenticity. [ABSTRACT FROM AUTHOR]

Abstract: The zeta-potentials of the self-assembled surface ionic surfactants (sodium dodecyl sulfate—SDS and hexadecyltrimethyl ammonium bromide—CTAB) on graphite surfaces were determined both from streaming potential and electrophoretic mobility measurements. The adsorption of the surfactants at graphite–liquid interfaces has been studied using atomic force microscopy (AFM) soft-contact imaging which shows the formation of linear, parallel hemicylinders with headgroups oriented towards the solution. The magnitude of the zeta-potential increased with an increase in surfactant concentration, reaching a constant value at a concentration corresponding to the point of surface micelle formation as confirmed from AFM imaging. The streaming potential and electrophoretic mobility measurements showed that the zeta-potentials of SDS and CTAB surface micelles adsorbed at the graphite surface were about -75 and +70mV, respectively, well in agreement with the values reported for bulk phase micelles in the literature. [Copyright &y& Elsevier]

The design of the IF protocol makes it difficult to reliably identify the originator of an IF packet, causing the defense against Distributed Denial of Service attacks to become one of the hardest problems on the Internet today. Previous solutions for this problem try to traceback to the exact origin of the attack by requiring every router's participation. For many reasons this requirement is impractical and the victim results with an approximate location of the attacker. Reconstruction of the whole path is also very difficult due to the sheer size of the Internet. This paper presents lightweight schemes for tracing back to the attack-originating AS instead to the exact origin itself. Once the attack-originating AS is determined, all further routers in the path to the attacker are within that AS and under the control of a single entity; which can presumably monitor local traffic in a more direct way than a generalized, Internet scale, packet marking scheme can. We furthermore, provide a scheme to prevent compromised routers from forging markings. [ABSTRACT FROM AUTHOR]

The structure of water in water-in-oil microemulsions used to synthesize oxalate precusor nanoparticles for the production of YBa2Cu3O7−x (YBCO) superconductor powder has been studied by FTIR–ATR spectroscopy of the O&z.sbnd;H stretching band. Two initial microemulsions are mixed together and nanoparticles are formed by a precipitation reaction in the cores of the reverse micelles of the resulting microemulsion. The shapes of the water O&z.sbnd;H stretching bands for the microemulsions before and after the reaction exhibit noticeable differences when normalized at their peaks. These differences have been quantified by decomposing the water O&z.sbnd;H stretching band into three components corresponding to water molecules with different types of hydrogen bonding. In the microemulsion after the precipitation and formation of oxalate precusor nanoparticles, the structure of water is characterized with an increased fraction of bound water. These bound water molecules are also connected with stronger H-bonds. We propose that upon synthesis of the precursor nanoparticles, the observed water structure changes are due to a thin water layer formed around the newly synthesized nanoparticles. [Copyright &y& Elsevier]

The inversion-layer capacitance Cinv of electrons in high-k/metal gate stacks (HKMGs) is studied theoretically and experimentally from the viewpoint of the penetration of electrons into the dielectrics. The numerical calculation of Cinv in the dielectric/substrate bilayer structure has clarified the influence of penetration on Cinv. Cinv in an HKMG is evaluated experimentally and is compared with the computational predictions in terms of the dependence on the dielectric boundary and the silicon crystal orientation. The consistency of the experiment and the calculation is the first evidence for the considerable modulation of Cinv due to penetration in the actual HKMG. Moreover, the dependence of Cinv on substrate biasing is investigated. The detailed analysis of Cinv in the system where the confinement of the inversion layer is intentionally changed has led to a further understanding of Cinv determined by penetration. [ABSTRACT FROM PUBLISHER]

HfO2 layers, 25-Å thick, were grown by cyclic Hf sputter deposition and room temperature oxidation steps on chemically oxidized Si(001). Subsequent in situ annealing and TiN deposition yield a high- \kappa gate-stack for which the original 8-Å-thick SiO2 layer is eliminated, as confirmed by transmission electron microscopy. Transistors fabricated with this gate-stack achieve an equivalent oxide thickness in inversion T_{\rm inv} =9.7 Å, with a gate leakage J_{g} =0.8 A/cm2. Devices fabricated without in situ annealing of the HfO2 layer yield a Tinv which increases from 10.8 to 11.2 Å as the oxidation time during each HfO2 growth cycle increases from 10 to 120 s, also causing a decrease in Jg from 0.95 to 0.60 A/cm2, and an increase in the transistor threshold voltage from 272 to 294 mV. The annealing step reduces Tinv by 1.5 Å (10%) but also increases the gate leakage by 0.1 A/cm2 (30%), and causes a 61 mV reduction in Vt . These effects are primarily attributed to the oxygen-deficiency of the as-deposited HfO2, which facilitates both the reduction of an interfacial SiO2 layer and a partial phase transition to a high- $\kappa $ cubic or tetragonal HfO2 phase. [ABSTRACT FROM AUTHOR]

Abstract: In this study, the effect of Cluster Carbon implantation and thermal annealing for recrystallization on the properties of phosphorus doped Si (Si:P) epitaxial films was investigated. Several Cluster Carbon implantation conditions and recrystallization annealing techniques based on solid phase epitaxy with rapid thermal annealing (RTA), spike RTA (sRTA), and millisecond laser annealing have been employed. It was found that a high substitutional carbon concentration can be achieved by laser annealing while high thermal budget annealing caused the loss of almost half of the substitutional carbon. The reduction of end of range defects and stacking faults/dislocation loops at the surface of carbon and phosphorus doped Si (Si:CP) layers through the use of cold implantation and fewer implantations was confirmed. Although sRTA activates phosphorus, additional laser annealing improves phosphorus activation further in the Si:CP layer. The phosphorus profile is abrupt with Cluster Carbon implantation when compared to no carbon implantation. [Copyright &y& Elsevier]

Abstract: We present an effective epitaxy process based on a cyclical deposition-etch (CDE) technique to obtain ultra-low resistivity in situ phosphorus-doped silicon carbon (SiCP) layers for raised source/drain applications. The combined low process temperature and high growth rate of the CDE technique is shown to maximize the incorporation of phosphorus and carbon into the crystal. We also present a complementary procedure based upon high-temperature annealing to further improve the phosphorus activation. This process and procedure enable the formation of raised SiCP source/drains on advanced 20nm fully-depleted-silicon-on-insulator devices with a carrier density up to 3×1020 cm−3 for 5×1020 cm−3 total P, and with fully-substitutional carbon in the range from 0% to 2%. It was found that a 1250°C millisecond laser anneal improves resistivity by 30% and 42% for SiP and SiC2.1%P, respectively. This result is in contrast with a 1060°C spike anneal, where the gain in activated P is shown to be insignificant for SiCP. It is shown that the formation of C clusters or precipitates during spike anneal adversely affects P activation. With an optimized annealing process, resistivity values as low as 0.46MΩcm for SiC2.1%P and 0.3MΩcm for SiP were obtained. [Copyright &y& Elsevier]

We investigate the determining mechanisms of the inversion-layer capacitance Cinv in the high-k/metal gate stacks, focusing on the two perturbative effects related with the dielectric properties. Those effects are the penetration of inversion-layer carriers into the dielectrics with a finite potential barrier and the image potential acting on the carriers adjacent to the dielectrics with permittivity different from that of the silicon substrate. The experimental and the theoretical analyses of the Cinv dependency on the crystal orientation of silicon substrates enable us to separate the two effects and to prove that the observed Cinv modulation in the high- k/metal gate stacks is attributable not to the image potential effect, but to the penetration effect. Moreover, we investigate the reduction of the total gate capacitance due to the Cinv in the advanced gate stacks scaled down to 0.66-nm equivalent oxide thickness. The influence of the elementary composition, the physical thickness, and the interface layer on a scaling loss due to the Cinv is experimentally evaluated. [ABSTRACT FROM AUTHOR]

Abstract: The effect of thermal heat treatment on carbon in in-situ phosphorous-doped silicon-carbon is studied as a function of annealing temperature and type. Films of 0 to 2% carbon were deposited using cyclic chemical vapor deposition at reduced pressures. Secondary ion-mass spectroscopy and high-resolution X-ray diffraction were employed to extract the total and substitutional carbon concentration in samples with phosphorous levels of mid-1020 cm-3. It was found that millisecond laser annealing drastically improves substitutionality while high thermal budget treatments (furnace, rapid-thermal, or spike annealing) resulted in an almost complete loss of substitutional carbon, independent of preceding or subsequent laser heat treatments. [Copyright &y& Elsevier]

Sulfur passivation of Ge(100) is achieved using aqueous ammonium sulfide (NH4)2S(aq). The passivation layer is largely preserved after atomic layer deposition of the high-κ dielectric material HfO2 when sufficiently low growth temperatures (e.g., 220 °C) are employed. Oxygen incorporation is moderate and results in an electrically passivating GeOS interface layer. The HfO2/GeOS/Ge gate stack exhibits lower fixed charge and interface state density than a more conventional HfO2/GeON/Ge gate stack fabricated via an ammonia gas treatment. [ABSTRACT FROM AUTHOR]