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We have studied light-induced photoconductivity degradation in an intrinsic hydrogenated and deuterated amorphous-silicon ͑a-Si͒ alloy. Deuterated a-Si turns out to be more stable under light exposure. A possible mechanism is proposed to explain this phenomenon. It is attributed to the highly efficient coupling between the localized Si-D wagging modes (ϳ510 cm Ϫ1 ) and the extended Si-Si lattice vibration modes (ϳ495 cm Ϫ1 ). The energy released from electron or hole capture at silicon dangling bonds causes localized vibrations of nearby Si-D bonds. The energy dissipates quickly to the background lattice and a higher recombination rate at local sites is needed in deuterated a-Si than in hydrogenated amorphous silicon to accumulate enough energy to break the nearby weak bonds.

This paper presents a novel transverse flux permanent magnet disk generator (TFPMDG) for wind power generation. The main features of its structure are the modular H-shaped stator cores and two simple rotor disks. What is different from the structures introduced in the references is that each H-shaped stator core is formed by two T-shaped iron cores and a permanent magnet (PM) rather than a complete H-shaped core, which makes the manufacturing simpler and easier. Each rotor disk consists of a rotor holder and several rotor bars, resulting in high robustness and reliability. Moreover, two circular coils in the H-shaped stator cores together with the stator disk are sandwiched by the two rotor disks, which improves the utilization of PMs. In this paper, the proposed TFPMDG is investigated in detail. Firstly, the structure and operating principle are introduced. Then, the magnetic circuit method is used to analyze the TFPMDG. Next, the three-dimensional (3D) finite element method (FEM) is employed to compute the magnetic field distribution and EMF at no load. According to the calculation result, the other three TFPMDGs with different shapes of rotor cores are proposed and analyzed for better back EMF, and then a generator with good performance is selected for load analysis. Finally, a prototype is fabricated and tested, and the simulated results are compared with the measured ones, which proves the rationality of the simulated results.

It has been shown that the spin Hall effect from heavy transition metals can generate sufficient spin-orbit torque and further produce current-induced magnetization switching in the adjacent ferromagnetic layer. However, if the ferromagnetic layer has in-plane magnetic anisotropy, probing such switching phenomenon typically relies on tunneling magnetoresistance measurement of nanosized magnetic tunnel junctions, differential planar Hall voltage measurement, or Kerr imaging approaches. We show that in magnetic heterostructures with spin Hall metals, there exist currentinduced in-plane spin Hall effective fields and unidirectional magnetoresistance that will modify their anisotropic magnetoresistance behavior. We also demonstrate that by analyzing the response of anisotropic magnetoresistance under such influences, one can directly and electrically probe magnetization switching driven by the spin-orbit torque, even in micron-sized devices. This pumpprobe method allows for efficient and direct determination of key parameters from spin-orbit torque switching events without lengthy device fabrication processes. †

No abstract

Variable-range hopping is usually the main electron transport mechanism of an organic semiconductor at low temperature. For an organic field-effect transistor at low temperature and under both high source-drain bias and high gate voltage, it is argued that multistep tunneling (MUST) can dominate charge transport. The MUST occurs through the assistance of randomly distributed localized states. The conductivity depends exponentially on the inverse of the square-root of electric field. This result explains well the recent experimental observation [A. S. Dhoot et al., Phys. Rev. Lett. 96, 246403 (2006)].

No abstract

We fabricate and measure a single-walled carbon nanotube transistor having a liquid-gate electrode. The ratio value of Ion∕Ioff is as high as 104, indicating the presence of a semiconducting channel. A passivation layer over the source/drain electrode greatly suppresses the liquid-gate leakage by about three orders of magnitude. The channel currents are noticeably distinct between two liquid samples: distilled water and aqueous solution (1×10−4M NaCl). This biological sensing ability is attributed to the different electrical double-layer capacitances with respect to the bulk part of the channel. The corresponding theoretical calculation is carried out in detail.