Uniform light emission from electrically driven plasmonic grating using multilayer tunneling barriers

Light emission by inelastic tunneling(LEIT)from a metal-insulator-metal tunnel junction is an ultrafast emission process.It is a promising platform for ultrafast transduction from electrical signal to optical signal on integrated circuits.However,existing procedures of fabricating LEIT devices usually involve both top-down and bottom-up techniques,which reduces its compatibility with the modern microfabrication streamline and limits its potential applications in industrial scale-up.Here in this work,we lift these restrictions by using a multilayer insulator grown by atomic layer deposition as the tunnel barrier.For the first time,we fabricate an LEIT device fully by microfabrication techniques and show a stable performance under ambient conditions.Uniform electroluminescence is observed over the entire active region,with the emission spectrum shaped by metallic grating plasmons.The introduction of a multilayer insulator into the LEIT can provide an additional degree of freedom for engineering the energy band landscape of the tunnel barrier.The presented scheme of preparing a stable ultrathin tunnel barrier may also find some applications in a wide range of integrated optoelectronic devices.

High Chern number phase in topological insulator multilayer structures:A Dirac cone model study

We employ the Dirac cone model to explore the high Chern number(C)phases that are realized in the magnetic-doped topological insulator(TI)multilayer structures by Zhao et al.[Nature 588419(2020)].The Chern number is calculated by capturing the evolution of the phase boundaries with the parameters,then the Chern number phase diagrams of the TI multilayer structures are obtained.The high-C behavior is attributed to the band inversion of the renormalized Dirac cones,along with which the spin polarization at theΓpoint will get increased.Moreover,another two TI multilayer structures as well as the TI superlattice structures are studied.

Composite Design of Low Thermal Conductivity Mullite Brick for Application to Cement Kiln

In order to restrain cement kiln shell＇ s thermal loss and potential safety hazards,composite design was employed of working layer,thermal preservation layer and thermal insulation layer.Thermal preservation layer＇ s boundary and strain were analyzed and the overall thermal conductivity was calculated.The result shows that the sinusoidal curve boundary combination is adopted between the working layer and thermal preservation layer,and the slope-shape with angle of 135 degrees between the thermal preservation layer and thermal insulation layer could relieve the strain concentration.Comprehensive thermal conductivity of the composite mullite brick decreases from the working layer 2.74 W·m^（-1）·K^（-1） to1.54 W·m^（-1）·K^（-1）.When applying the composite bricks in cement kilns,the kiln shell temperature is from50 ℃ to 70 ℃ lower than using normal bricks.

Calculation of high-temperature insulation parameters and heat transfer behaviors of multilayer insulation by inverse problems method

In the present paper, a numerical model combining radiation and conduction for porous materials is developed based on the finite volume method. The model can be used to investigate high-temperature thermal insulations which are widely used in metallic thermal protection systems on reusable launch vehicles and high-temperature fuel cells. The effective thermal conductivities（ECTs） which are measured experimentally can hardly be used separately to analyze the heat transfer behaviors of conduction and radiation for high-temperature insulation. By fitting the effective thermal conductivities with experimental data, the equivalent radiation transmittance, absorptivity and reflectivity, as well as a linear function to describe the relationship between temperature and conductivity can be estimated by an inverse problems method. The deviation between the calculated and measured effective thermal conductivities is less than 4%. Using the material parameters so obtained for conduction and radiation, the heat transfer process in multilayer thermal insulation（MTI） is calculated and the deviation between the calculated and the measured transient temperatures at a certain depth in the multilayer thermal insulation is less than 6.5%.