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We investigate the photoluminescence (PL) emission from InGaN/GaN multiple quantum-well structures before and after 1 MeV electron irradiation. The PL peak intensity exhibits a slight enhancement after low-dose electron irradiation (2 x 1013 e/cm²), and then decreases with the cumulative electron dose. Meanwhile, the full width at half maximum of the PL spectrum narrows after low-dose electron irradiation and widens when the irradiation dose is relatively high. With respect to the yellow photoluminescence, there is no significant change until the electron fluence has accumulated up to 1014 e/cm². [ABSTRACT FROM AUTHOR]

HCSB-DEMO concept design is carried out at SWIP. In order to handle power from a core plasma region, a super-X divertor is preliminarily designed and investigated for HCSB-DEMO. It increases the target surface area by expanding the magnetic flux surface with another X-point generated near the targets and increases the parallel connection length by moving the outer divertor target to larger R and Z. The heat load at the targets is investigated by B2.5-Eirene. With heating power flowing into SOL/divertor regions being P = 600MW, when the density at the separatrix is ne = 3.5×1019 m-3, the peak heat load at the inner and outer divertor is 9.2MW/m² and 3.7MW/m², respectively, which is much less than those of the standard divertor without impurity seeding, and also below the design targets (10MW/m²). Thus the super-X divertor may work well for HCSB-DEMO to solve the high heat load problem at the divertor target without impurity seeding from this preliminary concept design and simulation. [ABSTRACT FROM AUTHOR]

Beam manipulation by metallic nanoslit arrays with perpendicular cuts inside the slits was investigated numerically. The simulated results performed by the finite element method (FEM) show that perpendicular cuts with different heights can modulate phase retardation of the transmitted light through the slits. With the proper distribution of cut height, a focused beam is achieved in our metallic nanostructure with four-time amplitude at the focus point and half focal length compared to a slit array without cuts inside. By using asymmetric distribution of height amplitude, a beam deflection around 6° can also be realized in our design. [ABSTRACT FROM AUTHOR]

A conceptual design study of the HL-2M facility has shown that one can create not only a standard single-null divertor configuration on it, but also a second-order null (snowflake (SF)) configuration. For the SF divertor, the magnetic flux expansion closes to the separatrix and exceeds that of the standard configuration by more than a factor of 4 at the outer divertor. The heat load at the divertor targets of this innovative configuration has been investigated by using B2.5-Eirene. It is shown that the heat load it targets is different from that of the standard configuration. As a result of the magnetic flux expansion, the peak heat load reduces and does not concentrate on a small area near the separatrix. The heat load profile becomes flat as compared to the standard divertor. When the upstream density is 2.0×1019/m³ with 10MW heating power flowing into the SOL/divertor regions, the peak load at the outer divertor is 1.64MW/m² for the SF divertor, but it is 3.2MW/m² for the standard divertor, so the SF divertor can mitigate the heat load at the divertor targets when HL-2M operates at low plasma density and high heating power. [ABSTRACT FROM AUTHOR]

Benefitting from the higher quantum efficiency and sensitivity compared with the front-side illumination (FSI) CMOS image sensors (CISs), backside illumination (BSI) CMOS image sensors tend to replace CCDs and FSI CISs for space applications. However, the radiation damage effects and mechanisms of BSI CISs in the radiation environment are not well understood. We provide radiation effects due to 3 MeV proton irradiations of BSI CISs dedicated to imaging by the analyses of mean dark current increase, dark current nonuniformity and full well capacity in pixel arrays and isolated photodiodes. Additionally, the present annealing certifies the radiation-induced defects, which are responsible for the parameter degradations in BSI CISs. [ABSTRACT FROM AUTHOR]

We propose a simple iterative algorithm based on a temporally movable phase modulation process to retrieve the weak temporal phase of laser pulses. This unambiguous method can be used to achieve a high accuracy and to simultaneously measure the weak temporal phase and temporal profile of pulses, which are almost transform-limited. A detailed analysis shows that this iterative method has valuable potential applications in the characterization of pulses with weak temporal phase. [ABSTRACT FROM AUTHOR]

A new approach for enhancing the conversion efficiency of solar cells is proposed. A surface with columnar structures is employed on the fabrication of multi-crystalline silicon solar cells, for increasing the collection probability of photon-generated minority carriers in the cells. For comparison, three types of surfaces (planar surface, surfaces with columns of 12 μm in radius and columns of 9 μm in radius, respectively) are used. It is demonstrated that the cells with columnar structured surfaces have better spectral response and higher efficiencies than the cells with planar surface, while the cells with columns of 9 μm in radius show better spectral response than the cells with columns of 12 μm in radius. However, the cells with columns of 12 μm exhibit higher efficiencies than the cells with columns of 9 μm in radius for their difference in fill factors. Moreover, the effect of the columnar structured surface on the minority carrier collection efficiency is verified with wafers of different minority carrier lifetimes (0.5 μs and 1.0 μs). This work may significantly consider its potential in the manufacturing of high-efficiency solar cells at low cost by using low quality materials. [ABSTRACT FROM AUTHOR]

Long-term room-temperature annealing effects of InGaAs/InP quantum wells with different wells (namely triple wells and five wells embedded) and bulk InGaAs are investigated after high energy electron irradiation. It is observed that the photoluminescence (PL) intensity of bulk InGaAs materials is enhanced after low dose electron irradiation and the PL intensity for all the three samples is degraded dramatically when the electron dose is relatively high. With respect to the room-temperature annealing, we find that the PL intensity for both samples recovers relatively fast at the initial stage. The PL performance of multiple quantum-well samples shows better recovery after irradiation compared with the results of bulk InGaAs materials. Meanwhile, the recovery speed factors of multiple quantum-well samples are relatively faster than those of the bulk InGaAs materials as well. We infer that the recovery difference between the quantum-well materials and bulk materials originates from the fact that the radiation induced defects are confined in the quantum wells as a consequence of the free energy barrier between the In0.53Ga0.47As wells and InP barrier layers. [ABSTRACT FROM AUTHOR]

We perform first-principles calculations for ZnO thin films with oxygen vacancy defects. The densities of states, partial atomic densities of states, charge density differences and atomic populations are presented. We show that the SET process, i.e., from a high resistive state to a low resistive state, is attributable to the aggregation and regular arrangement of the oxygen vacancies, which causes the formation of conductive filaments and leads to the low resistive state of the system. [ABSTRACT FROM AUTHOR]

We fabricated Sb2Se3 thin film solar cells using tris(8-hydroxy-quinolinato) aluminum (Alq3) as an electron transport layer by vacuum thermal evaporation. Another small organic molecule of N,N'-bis(naphthalen-1-yl)-N,N'-bis(phenyl)benzidine (NPB) was used as a hole transport layer. We took ITO/NPB/Sb2Se3/Alq3/Al as the device architecture. An open circuit voltage (Voc) of 0.37 V, a short circuit current density (Jsc) of 21.2 mA/cm2, and a power conversion efficiency (PCE) of 3.79% were obtained on an optimized device. A maximum external quantum efficiency of 73% was achieved at 600 nm. The Jsc, Voc, and PCE were dramatically enhanced after introducing an electron transport layer of Alq3. The results suggest that the interface state density at Sb2Se3/Al interface is decreased by inserting an Alq3 layer, and the charge recombination loss in the device is suppressed. This work provides a new electron transport material for Sb2Se3 thin film solar cells. [ABSTRACT FROM AUTHOR]

Matter-wave interferometers with spin quantum states are attractive in quantum manipulation and precision measurements. Here, five spatial interference patterns corresponding to the full spin states are observed in each run of the experiment, by the combination of the Majorana transition according to the exponential modulation of the magnetic field pulse decline curve and radio frequency coupling among multiple magnetic sub-states. Compared to the realization of two Majorana transitions, the interference fringe for the magnetic field insensitive state also has a higher contrast. After spatially overlapping the full magnetic sub-state interference patterns dozens of times in consecutive experimental measurements, clear fringes are still observed, indicating the great stability of the relative phases of different components. This indicates the potential to achieve an interferometer with multiple spin clocks. [ABSTRACT FROM AUTHOR]

A novel symmetric plasmonic structure consisting of a metal-insulator-metal waveguide and a rectangular cavity is proposed to investigate Fano resonance performance by adjusting the size of the structure. The Fano resonance originates from the interference between a local quadrupolar and a broad spectral line in the rectangular cavity. The tuning of the Fano profile is realized by changing the size of the rectangular cavity. The nanostructure is expected to work as an excellent plasmonic sensor with a high sensitivity of about 530nm/RIU and a figure of merit of about 650. [ABSTRACT FROM AUTHOR]

Vickers hardness calculations of eleven wurtzite-structured semiconductors are performed based on the microscopic hardness model. All the parameters are obtained from first-principles calculations. There are two types of chemical bonds in wurtzite-structured crystals. The overlap populations of the two types of chemical bonds in lonsdaleite are chosen as Pc for wurtzite structure. The calculated bond ionicity values of the wurtzite-structured semiconductors are in good agreement with the ionicities from the dielectric definition. When the hardness of wurtzite-structured crystal is higher than 20GPa, our calculated Vickers hardness is within 10% accuracy. Therefore, the hardness of novel wurtzite-structured crystal could be estimated from first-principles calculations. [ABSTRACT FROM AUTHOR]

Based on the hexagonal BN structure, six possible layered B2CN structures are constructed. Their total energies, lattice constants as well as electronic properties are calculated using the ab initiopseudopotential density functional method within the local density approximation. The calculated results show that the B2CN-V configuration with AA stacking sequence is the most stable among the six B2CN layered structures. The characteristics of electronic structures indicate that the B2CN-V shows metallicity, which mainly comes from -B1-C-B1-C- chains. [ABSTRACT FROM AUTHOR]

A chemical reaction for the preparation of B-C-N compounds by using carbon tetrachloride (CCl4), boron tribromide (BBr3), lithium nitride (Li3N) and sodium as reactants has been carried out at the temperature of 400°C. Measurements of FTIR, XRD, TEM and EELS show that two kinds of compounds have been formed in the prepared sample. One is hollow sphere-like C-N with an amorphous structure; the other is piece-like polycrystalline B-C-N with the hexagonal structure. Their determined compositions are close to C3N and BC2N, respectively. [ABSTRACT FROM AUTHOR]

We report the experimental realization of quantum degenerate Fermi gases of 87Sr atoms under controlled 10- and dual-nuclear-spin configurations. Based on laser cooling and evaporative cooling, we achieve an ultracold Fermi gas of 105 atoms equally distributed over 10 spin states, with a temperature of T/TF=0.21. We further prepare a dual-spin gas by optically pumping atoms to the mF=9/2 and mF=7/2 states and observe a slightly lower T/TF than that for a 10-spin gas under the same trapping condition, showing efficient evaporative cooling under a decreasing numberof spin states () despite the increasing importance of Pauli exclusion. Given that rethermalization becomes less efficient withapproaching unity, we evaporatively cool an almost polarized gas to 130 nK. The simple and efficient preparation of ultracold Fermi gases of 87Sr with tunable spin configurations provides a first step towards engineering topological quantum systems. [ABSTRACT FROM AUTHOR]

We present an experimental method to obtain neutral beam injection (NBI) power scaling laws with operating parameters of the NBI system on HL-2A, including the beam divergence angle, the beam power transmission efficiency, the neutralization efficiency and so on. With the empirical scaling laws, the estimating power can be obtained in every shot of experiment on time, therefore the important parameters such as the energy confinement time can be obtained precisely. The simulation results by the tokamak simulation code (TSC) show that the evolution of the plasma parameters is in good agreement with the experimental results by using the NBI power from the empirical scaling law. [ABSTRACT FROM AUTHOR]

A pressure-induced phase transition and stability in Si2CN4 polymorphs under high pressure are studied by first-principles calculations. The result shows that the phase transition pressure of a- and b-Si2CN4 to the cubic spinal phase is 29.9 GPa and 27.5 GPa predicted by thermodynamic method respectively. Under ambient condition, all of the three Si2CN4 polymorphs are metastable with positive formation enthalpy. Unlike the stability of Si3N4 polymorphs, a-Si2CN4 is more stable than the b phase. [ABSTRACT FROM AUTHOR]