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Optical switch-on of a high-voltage (12 kV class) 4H-SiC thyristor to a current I = 100 A is reported. The importance of the dI/dt ramp and the turn-on spread for obtaining the maximum switched-on current I max is discussed. It is demonstrated that I max can be substantially raised by using a mixed resistive-inductive load.

An omnidirectional antireflection (AR) coating for a deep-ultraviolet (UV) AR band is designed and fabricated on the sapphire substrate of a deep-UV flip-chip light-emitting diode (LED) device. The two-layer AR coating uses the tailored- and low-refractive index nanoporous alumina fabricated by glancing-angle deposition methodology. The AR coating effectively matches the refractive indices between the air and sapphire substrate. At close-to-normal angles of incidence, this AR coating almost completely eliminates the Fresnel reflection at the sapphire/air interface of the deep-UV LED device. The resulting improvement of the light-extraction efficiency by 8% is in good agreement with the simulation results. For a total thickness of 172 nm for the two-layer AR coating, extinction was negligible (<2%). The results show that nanoporous alumina thin films are excellent tailored- and low-refractive index thin film materials for high-performance deep-UV AR coating applications.

www.particle-journal.com www.MaterialsViews.com COMMUNICATIONsubstrates for 2D morphology-controlled ZnO nanostructure growth. Graphene is a 2D carbon nanostructure, which has been studied extensively in recent years due its remarkable mechanical, optical, and electronic properties. [ 13 ] These properties makes graphene a promising candidate for many potential applications including electronic and optical devices. Graphene electrodes with nanostructures can also be applied as synergistic electrodes for different fl exible and transparent conducting devices. The growth mechanism of the synthesized 2D ZnO nanostructures is studied in detail with the help of scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), and selected area electron diffraction (SAED). Based on the data, we believe that ZnO nanofl akes are oriented along (0001) plane and grow laterally along (0110) plane. Furthermore, the electrical and optical data show excellent conduction and transmission properties, respectively. Our synthesis method is a low-cost, low-temperature, scalable, and potentially high-throughput process, which can be further extended for the synthesis of wide range of other 2D materials for different applications in electronics and optoelectronics devices.We used zinc nitrate hexahydrate [ZNH; Zn(NO 3 )·6H 2 O] and hexamethylenetetramine [HMT; (CH 2 ) 6 ·N 4 ] (both from SigmaAldrich) for the sonochemical synthesis of ZnO nanofl akes. [ 12 ] ZNH provides Zn 2+ ions and H 2 O molecules in the solution provide O 2− ions. HMT has been used as a shape-inducing polymer in ZnO nanowire growth as polymer as it attaches to the nonpolar facets of ZnO cutting the supply of Zn 2+ ions, thus allowing the growth of ZnO in only <0001> direction. [ 14 ] However, the shape of the nanostructures strongly depends on the concentration of ZNH/HMT solutions, which affects the precipitation mechanism of the oxide. [ 15,16 ] It was observed that as the concentration of ZNH/HMT aqueous solution increased, the length of the ZnO nanorods decreased. [ 15 ] In the present case, the concentration of the precursors is increased by 10-20 times and the sonication amplitude is increased by 20% compared with the earlier process. [ 12 ] The process temperature does not exceed 70 ° C, as amplitude of the sonication is increased. At the higher concentrations used in this process and fast reaction rates achieved under sonication, HMT releases large amounts of OH − and NH 4 + ions in a short period of time. At this higher concentrations, precipitation of Zn 2+ ions occurs at faster rate than required for HMT-assisted oriented growth of ZnO nanostructures, [ 14,15 ] resulting in growth of nonpolar planes of ZnO along with polar (0001) plane forming parallelogram-shaped 2D ZnO nanofl akes.Figure 1 a,b shows the SEM pictures of the ZnO nanofl ake growth on Si substrate at 30 s and 1 min. 2D ZnO nanofl akes grow from sheet structures to hexagonal crystal structure, Semiconductor nanostructures have attracted considerable research i...

The paper analyzes the long-term noise monitoring data using the AutoRegressive Integrated Moving Average (ARIMA) modeling technique. Box-Jenkins ARIMA approach has been adapted to simulate the daily mean L Day (06-22 h) and L Night (22-06 h) in A-and C-weightings in conjunction with single-noise metrics, daynight average sound level (DNL) for a period of 6 months. The autocorrelation function (ACF) and partial autocorrelation function (PACF) have been obtained to find suitable orders of autoregressive (p) and moving average (q) parameters for ARIMA (p, d, q) models so developed for all the single-noise metrics. The ARIMA models, namely, ARIMA(0,0,14), ARIMA(0,1,1), ARIMA(7,0,0), ARIMA(1,0,0) and ARIMA(0,1,14), have been developed as the most suitable for simulating and forecasting the daily mean L Day dBA, L Night dBA, L Day dBC, L Night dBC, and day-night average sound level (DNL) respectively. The performance of the model so developed is ascertained using the statistical tests. The work reveals that the ARIMA approach is reliable for time-series modeling of traffic noise levels. © 2015 Institute of Noise Control Engineering.

An electron beam evaporation method is used to prepare In2O3 films with and without Sn doping. It is shown that highly transparent and conducting films can be prepared at substrate temperature as low as 200 degrees C. The characteristic feature of such films is their high carrier density and high infrared reflectivity. The lowest resistivity is found to be 2.4*10-4 Omega cm with a carrier concentration of 8*1020 cm-3 and mobility of about 30 cm2 V-1 s-1 at the doping level of 4 mol.% SnO2. These polycrystalline films show a highly preferred orientation. On the basis of Hall measurements and structural data, sources of scattering in these films are suggested.