Formation of metal-semiconductor (M-S) contacts at sub-20 nanometer range is a key requirement for down-scaling of semiconductor devices. However, electrical measurements of M-S contacts at this scale have exhibited dramatic change in the current-voltage (I-V) characteristics compared to that of conventional (or planar) Schottky contacts. This change is actually attributed to the limited metal contact region where the transferred charge from the semiconductor into the metal is confined to a small surface area, which in turn results in an enhanced electric field at the nano-M-S interface. We here present detailed theoretical models to analyze the nano-M-S junctions at 10 nm contact range and then implement this analysis on the experimental data we conducted under these conditions. Both theoretical and experimental results demonstrate a significant effect of the contact size on the electronic structure of the M-S junctions and thus on the I-V characteristics. This effect is rather prominent when the size of the metal contact is substantially smaller than the width of conventional depletion region of the relevant planar M-S contacts. Published by AIP Publishing.

Using autonomously operating mobile sensor nodes to form adaptive wireless sensor networks has great potential for monitoring applications in the real world. Especially in, e.g., disaster response scenarios—that is, when the environment is potentially unsafe and unknown—drones can offer fast access and provide crucial intelligence to rescue forces due the fact that they—unlike humans—are expendable and can operate in 3D space, often allowing them to ignore rubble and blocked passages. Among the practical issues faced are the optimizing of device–device communication, the deployment process and the limited power supply for the devices and the hardware they carry. To address these challenges a host of literature is available, proposing, e.g., the use of nature-inspired approaches. In this field, our own work (bio-inspired self-organizing network, BISON, which uses Voronoi tessellations) achieved promising results. In our previous approach the wireless sensors network (WSN) nodes were using knowledge about their coverage areas center of gravity, something which a drone would not automatically know. To address this, we augment BISON with a genetic algorithm (GA), which has the benefit of further improving network deployment time and overall coverage. Our evaluations show, unsurprisingly, an increase in energy cost. Two variations of our proposed GA-BISON deployment strategies are presented and compared, along with the impact of the GA. Counter-intuitively, performance and robustness increase in the presence of noise.

We have studied the dependence of Schottky junction (I–V) characteristics on the metal contact size in metal–semiconductor (M–S) junctions using different metal nanoprobe sizes. The results show strong dependence of (I–V) characteristics on the nanoprobe size when it is in contact with a semiconductor substrate. The results show the evolution from sub-10 nm reversed Schottky diode behavior to the normal diode behavior at 100 nm. These results also indicate the direct correlation between the electric field at the M–S interface and the Schottky rectification behavior. The effect of the metal contact size on nano-Schottky diode structure is clearly demonstrated, which would help in designing a new type of nano-devices at sub-10 nm scale.

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Continuous and low-cost broadcast authentication is a fundamental security service for distributed sensor networks. This paper presents a novel development of a continuous and low-overhead broadcast authentication protocol named enhanced Infinite timed-efficient stream-loss tolerant authentication (enhanced Inf-TESLA) protocol, based on the Inf-TESLA protocol, whose continuous authentication is limited to the duration of its keychains. The enhanced Inf-TESLA protocol satisfies important security properties, including lower communication and computational overhead; a continuous generation of keychains without the need to establish synchronization packets; scalability to a large network; and resistance to masquerading, modification, man-in-the-middle, and replay attacks. We also highlighted an unaddressed authentication issue in the last packets of the original TESLA protocol and proposed a corresponding solution. We performed a simulation analysis using JAVA and proved that, compared to the Inf-TESLA protocol, the enhanced Inf-TESLA protocol can continuously authenticate packets for the entire lifetime of the receiver. We also compared the enhanced Inf-TESLA protocol with the original TESLA protocol in terms of time complexity and critical authentication processes. The results revealed the superiority of the enhanced Inf-TESLA protocol over the original TESLA protocol in terms of the message authentication code (MAC) value generation time and packet authentication time, which we believe can significantly improve the lifetime and lower the energy expenditure of Internet of Things devices with limited power sources. INDEX TERMS Continuous authentication, Internet of Things, low overhead, TESLA protocol, time complexity I. INTRODUCTIONThe development of the Internet of Things (IoT) technology has enabled billions of devices around the world to be connected to the Internet to collect and share data, create a level of digital intelligence, and support real-time communication of data [1]. Majority of devices that contribute to the IoT are constrained devices that have access to user information and daily life changes, which makes them vulnerable to cybersecurity attacks. Counter actions include using IoT devices as entry points to access other parts of the network or as a bait to turn turn down the attacker's system down. Constrained devices, such as sensors or smart devices, have limited CPU, memory, and power resources, which restricts the use of security protocols in protecting the privacy of their transferred data [1], [2].The main challenges in securing broadcast communication are source and integrity authentication, verifying that the received data comes from a legitimate source and has not been altered en-route [3]. Furthermore,