Fabrication of a Superhydrophobic Surface from a Smectic Liquid‐Crystal Defect Array

A novel fabrication method is developed for the preparation of superhydrophobic surfaces. The procedure uses focal conic structures of semi‐fluorinated smectic liquid crystals (LCs) whose periodic toric focal conic domains (TFCDs) are prepared on a surface modified substrate. Reactive ion etching (RIE) on the periodic TFCD surface leads to a superhydrophobic surface with a water contact angle of ～160° and a sliding angle of ～2° for a 10 µL water droplet. The results show that this phenomenon is due to the development of a dual‐scale surface roughness arising from the nanoscale protuberance caused by applying the RIE process to the top of the microscale TFCD arrays. The unique surface behavior is further verified by demonstrating that RIE on a flat lamellar liquid crystal film, in which the director is aligned parallel with surface, results in a relatively low hydrophobicity as compared to when periodic TFCDs are subjected to REI. The observations made in this publication suggest that a new approach exists for selecting potential candidates of superhydrophic surface formation based on spontaneous self‐assembly in smectic liquid‐crystalline materials.     

Optical and Electrical Properties of TixSi1‐xOy Films

Ti_xSi_1xO_y (TSO) thin films are fabricated using plasma‐enhanced atomic layer deposition. The Ti content in the TSO films is controlled by adjusting the sub‐cycle ratio of TiO₂ and SiO₂. The refractive indices of SiO₂ and TiO₂ are 1.4 and 2.4, respectively. Hence, tailoring of the refractivity indices from 1.4 to 2.4 is feasible. The controllability of the refractive index and film thickness enables application of an antireflection coating layer to TSO films for use as a thin film solar cell. The TSO coating layer on an Si wafer dramatically reduces reflectivity compared to a bare Si wafer. In the measurement of the current‐voltage characteristics, a nonlinear coefficient of 13.6 is obtained in the TSO films.     

Effect of capping layer and post-CMP surface treatments on adhesion between damascene Cu and capping layer for ULSI interconnects

The effect of the type of capping layer and post-CMP surface treatments on the adhesion between damascene Cu and the capping layer was investigated. The CMPed-surface was treated by six methods divided into four groups which consisted of no surface treatment, cleaning by plasma with vacuum break, cleaning by plasma without vacuum break and cleaning by the wet chemical method. SiN_x and SiC were used to cap the surface after the post-CMP cleaning. The adhesion strength between Cu and the capping material was measured using a sandwiched structure constructed for the four point bending test. The X-ray photoemission spectroscopy analysis showed that the adhesion strength is related to the interfacial chemical bonds. The adhesion is influenced by the presence of contaminants and residual oxygen which inhibit the bonding of Si and Cu.     

Closed-Form Exact BER and Optimization of Generalized Orthogonal STBCs

The closed-form exact bit error rate (BER) expressions of generalized orthogonal space-time block codes (OSTBCs) are first derived for quadrature amplitude modulation (QAM) and phase shift keying (PSK) constellations in spatially white Rayleigh multiple input multiple output (MIMO) channels. Then this analysis is generalized to arbitrarily spatially correlated MIMO channels. Based on the BER analysis, the transmission power of the generalized OSTBCs is optimized such that the average BER is minimized. Furthermore, the optimum transmit power which maximizes the upper-bound of the capacity is derived in closed-form.     

Coordination of wavelength and time-window assignment in WDM-based TDM hybrid-PONs

In passive optical networks (PONs), the low effectiveness in terms of service utilization and network evolution have been important design issues. In this article, we introduce a hybrid access network architecture, so called scalable WDM-based Ethernet hybrid-PON (SWE-PON), which features a wavelength-division-multiplexed (WDM) feeder network using a combination of tunable laser device (TLD) and cyclic arrayed waveguide grating (AWG) and time-division-multiplexed (TDM) distribution network based on a reflective transmission mode. Necessary conditions needed to guarantee flawless packet transmission through normal WDM/TDM hierarchical PONs including the SWE-PON, are analyzed. We also propose a hierarchical fair time-window allocation mechanism which coordinates wavelength assignment and time-window bandwidth allocation so that high link utilization and fair bandwidth allocation are guaranteed in every multiplexing level.

A 0.2 V, 480 kb Subthreshold SRAM With 1 k Cells Per Bitline for Ultra-Low-Voltage Computing

A 2 muW, 100 kHz, 480 kb subthreshold SRAM operating at 0.2 V is demonstrated in a 130 nm CMOS process. A 10-T SRAM cell allows 1 k cells per bitline by eliminating the data-dependent bitline leakage. A virtual ground replica scheme is proposed for logic "0" level tracking and optimal sensing margin in read buffers. Utilizing the strong reverse short channel effect in the subthreshold region improves cell writability and row decoder performance due to the increased current drivability at a longer channel length. The sizing method leads to an equivalent write wordline voltage boost of 70 mV and a delay improvement of 28% in the row decoder compared to the conventional sizing scheme at 0.2 V. A bitline writeback scheme was used to eliminate the pseudo-write problem in unselected columns.     

The Operation Characteristics of an Alternating Current Plasma Display Panel With Si-Doped MgO Protecting Layer

In this paper, the operation characteristics of an ac plasma display panel (PDP) with Si-doped MgO protecting layer are investigated. The test panels are fabricated with the protecting layers of conventional MgO and Si-doped MgO, and the operation voltage margin, luminous efficacy, and address discharge time lag are observed. Even though the test panel with Si-doped MgO protecting layer showed lower operation voltages, higher luminous efficacy, and shorter statistical discharge time lag, its addressing discharge characteristics become deteriorated as the scanning time is increased from the end time of the reset period. The photon-induced surface conductivity increased by Si doping into MgO, and surface charges on the Si-doped MgO protecting layer showed faster decay characteristics compared to those on the conventional one. It is believed that the impurity doping into the protecting layer can improve the short-period characteristics of an ac PDP, but the long-term stability of surface charge retention is deteriorated.     

Reconfigurable microstrip antenna with polarisation diversity

A single probe-fed reconfigurable microstrip patch antenna with symmetric cross slots is proposed. By controlling four pin diodes on the patch slots, the proposed antenna has right hand circular polarisation, left hand circular polarisation or linear polarisation.     

An Intelligent Product Recommendation Model to Reflect the Recent Purchasing Patterns of Customers

Mobile Networks and Applications - This study suggests a new product recommendation model to reflect the recent purchasing patterns of customers. There are many methods to measure the similarity...