Nitride-based blue-light-emitting diodes having a moth-eye structure were fabricated on the backside of a 6H-SiC substrate. The light extraction efficiency and the corresponding output power were increased by 3.8 time...
Nitride-based blue-light-emitting diodes having a moth-eye structure were fabricated on the backside of a 6H-SiC substrate. The light extraction efficiency and the corresponding output power were increased by 3.8 times compared with those of an LED having the conventional structure. The results of theoretical analysis agree with these findings.
The spin and orbital ordering in Y1−xLaxVO3 (0.30 ⩽ x ⩽ 1.0) has been studied to map out the phase diagram over the whole doping range 0 ⩽ x ⩽ 1. The phase diagram is compared with that for RVO3 (R = rare earth or Y) ...
详细信息
The spin and orbital ordering in Y1−xLaxVO3 (0.30 ⩽ x ⩽ 1.0) has been studied to map out the phase diagram over the whole doping range 0 ⩽ x ⩽ 1. The phase diagram is compared with that for RVO3 (R = rare earth or Y) perovskites without A-site variance. For x > 0.20, no long-range orbital ordering was observed above the magnetic ordering temperature TN; the magnetic order is accompanied by a lattice anomaly at a Tt ⩽ TN as in LaVO3. The magnetic ordering below Tt ⩽ TN is G type in the compositional range 0.20 ⩽ x ⩽ 0.40 and C type in the range 0.738 ⩽ x ⩽ 1.0. Magnetization and neutron powder diffraction measurements point to the coexistence below TN of the two magnetic phases in the compositional range 0.4 x x ⩽ 1.0 are characterized by an additional suppression of a glasslike thermal conductivity in the temperature interval TN T T* and a change in the slope of 1/χ(T). We argue that T* represents a temperature below which spin and orbital fluctuations couple together via λL•S.
A novel copolymer (PG-PNIPAM) composed of polyglycerol (PG) as core and poly(N-isopropylacrylamide)(PNIPAM) as arms was prepared by the radical addition-fragmentation transfer polymerization (RAFT) of NIPAM in the pre...
详细信息
A novel copolymer (PG-PNIPAM) composed of polyglycerol (PG) as core and poly(N-isopropylacrylamide)(PNIPAM) as arms was prepared by the radical addition-fragmentation transfer polymerization (RAFT) of NIPAM in the presence of PG with multi-trithiolcarbonate groups (PG-TTC). The results showed that the RAFT polymerization was controllable and nearly all trithiolcarbonates groups on PG took part in the polymerization. The final PG-PNIPAM copolymer showed a thermally dependent hydrophobic/hydrophilic transition around 28-30 ℃.
The appendix to the paper, “Thermodynamics of the superconducting phase transformation in high Tc ceramics with magnetoelectric effects,” J. Mater. Res., Vol. 4, No. 1, Jan/Feb 1989, pp. 33–38, contains typesetting...
The appendix to the paper, “Thermodynamics of the superconducting phase transformation in high Tc ceramics with magnetoelectric effects,” J. Mater. Res., Vol. 4, No. 1, Jan/Feb 1989, pp. 33–38, contains typesetting errors.
This study examined the interfacial adhesion, mechanical, and thermal properties of compatibilizing agent-treated and non-treated biocomposites as a function of the type of compatibilizing agent. The tensile strength,...
详细信息
Control over the 1.5 µm emission from erbium is desirable for communication and computational technologies because the erbium emission falls in the window of maximum transmission for silica based fiber optics. Tu...
Control over the 1.5 µm emission from erbium is desirable for communication and computational technologies because the erbium emission falls in the window of maximum transmission for silica based fiber optics. Tunable, narrow, directional, and enhanced erbium emission from silicon based 1-D photonic bandgap structures will be demonstrated. The structures are prepared by anodic etching of crystalline silicon and consist of two highly reflecting Bragg reflectors sandwiching an active layer. The cavities are doped by electro-migrating the erbium ions into the porous silicon matrix, followed by high temperature oxidation. By controlling the oxidation temperature, porosity, and thickness of the structure, the position of the erbium emission is tuned to emit in regions where the normal erbium emission is very weak. The erbium emission from the cavity is narrowed to a full width at half maximum (FWHM) of 12 nm with a cavity quality factor Q of 130, highly directional with a 20 degree emission cone around the normal axis, and enhanced by more than one order of magnitude when compared to its lateral emission. Erbium photoluminescence (PL) from porous silicon 2-D photonic bandgap structures is also demonstrated.
Nanoindentations were created in the GaAs(100) surface to act as strain centers for the controlled nucleation and patterning of InAs quantum dots. A systematic approach is taken to understand the indent deformation pr...
Nanoindentations were created in the GaAs(100) surface to act as strain centers for the controlled nucleation and patterning of InAs quantum dots. A systematic approach is taken to understand the indent deformation processes that may lead to precision patterning capabilities for a broad range of nanostructures. Indents were generated using loads below 450 μN with a sharp cube corner indenter. Site-specific cross-sectional thinning of nanoindents (down to 100 nm in size) has been achieved using the in-situ ‘lift-out’ technique. This allowed for observation of subsurface deformation by transmission electron microscopy (TEM). The crystal was observed to deform solely by dislocation activity with no evidence of amorphization, twinning, fracture, or phase transformation. It is shown that the single phase deformation of GaAs can be well characterized and controlled, which should allow for exploitation of the dislocation strain field to bias nucleation of self-assembled quantum dots.
暂无评论