Dielectric elastomers are of interest for actuator applications due to their large actuation strain, high bandwidth, high energy density, and their flexible nature. If future dielectric elastomers are to be used reliably in applications that include soft robotics, medical devices, artificial muscles and electronic skins, there is a need to design devices that are tolerant to electrical and mechanical damage. In this paper, we provide the first report of self-healing of both electrical breakdown and mechanical damage in dielectric actuators using a thermoplastic methyl thioglycolate modified styrene-butadiene-styrene (MGSBS) elastomer. The self-healing functions are examined from the material to device level by detailed examination of the healing process, and characterisation of electrical properties and actuator response before and after Complete Manuscript

We demonstrate that trimethylamine borane can exhibit desirable piezoelectric and pyroelectric properties. The material was shown to be able operate as a flexible film for both thermal sensing, thermal energy conversion and mechanical sensing with high open circuit voltages (>10 V). A piezoelectric coefficient of d33≈10–16 pC N−1, and pyroelectric coefficient of p≈25.8 μC m−2 K−1 were achieved after poling, with high pyroelectric figure of merits for sensing and harvesting, along with a relative permittivity of ϵ33σ≈ 6.3.

The impact of trench defects in blue InGaN/GaN light emitting diodes (LEDs) has been investigated. Two mechanisms responsible for the structural degradation of the multiple quantum well (MQW) active region were identified. It was found that during the growth of the p-type GaN capping layer, loss of part of the active region enclosed within a trench defect occurred, affecting the top-most QWs in the MQW stack. Indium platelets and voids were also found to form preferentially at the bottom of the MQW stack. The presence of high densities of trench defects in the LEDs was found to relate to a significant reduction in photoluminescence and electroluminescence emission efficiency, for a range of excitation power densities and drive currents. This reduction in emission efficiency was attributed to an increase in the density of non-radiative recombination centres within the MQW stack, believed to be associated with the stacking mismatch boundaries which form part of the sub-surface structure of the trench defects. Investigation of the surface of green-emitting QW structures found a two decade increase in the density of trench defects, compared to its blue-emitting counterpart, suggesting that the efficiency of green-emitting LEDs may be strongly affected by the presence of these defects. Our results are therefore consistent with a model that the “green gap” problem might relate to localized strain relaxation occurring through defects.

The reduction of CO2 into useful hydrocarbon chemicals has attracted significant attention in light of the depletion in fossil resources and the global demand for sustainable sources of energy. In...

B 12 As 2 / SiC pn heterojunction diodes based on the radiation-hard B 12 As 2 deposited on ͑0001͒ n-type 4H-SiC via chemical vapor deposition were demonstrated. The diodes exhibit good rectifying behavior with an ideality factor of 1.8 and a leakage current as low as 9.4 ϫ 10 −6 A / cm 2 . Capacitance-voltage measurements using a two-frequency technique showed a hole concentration of ϳ1.8-2.0ϫ 10 17 cm −3 in B 12 As 2 with a slight increase near the interface due to the presence of an interfacial layer to accommodate lattice mismatch. Band offsets between the B 12 As 2 and SiC were estimated to be ϳ1.06 eV and 1.12 eV for conduction band and valance band, respectively. © 2010 American Institute of Physics. ͓doi:10.1063/1.3443712͔ Icosahedral boron arsenide ͑B 12 As 2 ͒ is a wide band gap boron-rich semiconductor ͑E g Ϸ 3.20 eV at room temperature 1 ͒. Its structure is based on 12-boron-atom icosahedra residing at the lattice points of a rhombohedral unit cell, with an As-As chain lying along its ͓111͔ axis ͑the body diagonal͒ ͑Refs. 2 and 3͒ ͓Fig. 1͑a͔͒. The boron atoms in the icosahedra are bonded by so-called three-centered bonds, i.e., a pair of electrons is shared among three boron atoms. As a consequence of this unique structure and bonding, B 12 As 2 has extraordinary radiation tolerance via self-healing mechanisms. In addition, it has a high melting temperature, and excellent mechanical properties, making B 12 As 2 highly attractive for applications under harsh conditions. Further details on the material properties of B 12 As 2 can be found in Refs. 1-7, and reference therein.A key potential application of B 12 As 2 is for compact solid-state thermal neutron detectors because 10 B has one of the highest thermal neutron ͑0.0259 eV͒ capture crosssections, ϳ3840 b of all elements. 4 He ions passing through the material. Compared with the present mature neutron detection technology employing gas-filled, proportional counters, or doped scintillating plastic fibers, solidstate neutron detectors would have reduced size and weight features that are beneficial for applications in portable devices or space. A further potential application is for betavoltaics, converting nuclear energy into electrical power, for small-scale long-lifetime batteries, e.g., remote sensors and peacemakers, where present materials are susceptible to radiation damage.9 Despite this great potential, no success has been achieved in fabricating B 12 As 2 based devices up to date, presumably due to the difficulty in growing high crystalline quality B 12 As 2 . In this paper, we report the fabrication of B 12 As 2 / SiC pn diodes, and present a detailed analysis of their electrical properties.Vertical heterojunction diodes were fabricated by epitaxially depositing B 12 As 2 on 300 m thick silicon-face ͑0001͒ n-type 4H-SiC ͑n Ϸ 10 18 cm −3 ͒ using chemical vapor deposition ͑CVD͒ at 1350°C under a constant total pressure of 100 Torr using 1% B 2 H 6 in H 2 and 2% AsH 3 in H 2 in hydrogen atmosphere. More details on the growth and its microstru...