Thermal conductivity of single-crystal boron-doped diamond (BDD) was studied in comparison with high-quality pure IIa-type diamond in the temperature range from 20 to 400 K. Boron content in BDD was about 1019 cm−3 that is a typical value of p+ substrates used for power device applications. The thermal conductivity of BDD is about 10 times less than that of IIa diamond near 100 K, but above room temperature the difference is <30%. The observed deviation mostly takes place due to acoustic phonon scattering on extended structural defects occurring in synthetic diamond at high boron content.

Transparent high refractive index materials are of the central importance for the development of metasurface in visible range. Titanium dioxide (TiO2) has been considered as a perfect candidate due to its wide band gap and high refractive index. However, till now, it is still quite challenging to fabricate high-quality TiO2 films with high refractive indices and low losses. Here we demonstrate the fabrication of high-quality TiO2 film using an electron-beam evaporation method. We show that the post-annealing conditions play key roles in the microstructure crystallographic and the optical refractive index of the TiO2 films. A predominately oriented TiO2 film has been achieved by annealing at 700 °C in oxygen ambient. The refractive index is as high as 2.4, and the corresponding loss is negligible at 632 nm. Further studies on dielectric antennas show that our TiO2 film can be an ideal platform to fabricate metasurface in visible frequency range. We believe that our research will be important for the advances of all-dielectric metasurfaces.

In nanocrystalline (nc) metals, it is still not clear how local grain boundary (GB) structures accommodate GB migration at atomic scales and what dominates the motion of atoms at the inherently unstable GB front. Here, we report the adjustment of the local GB structures at atomic scales during self-driven GB migration, simultaneously involving GB dissociation, partial dislocation emission from GB, and faceting/defaceting in the nc Cu. Furthermore, we reveal that the fundamental of GB migration ability is closely related to the local structure, i.e. the GB segment consisting of “hybrid” structural units and delocalized GB dislocations is relatively unstable.

We analyze the effect of functionalization in the surface of zinc oxide crystal structure by 3-mercaptopropionic acid. X-ray powder diffraction data and extended x-ray absorption fine structure studies confirms a wurtzite structure. However, the morphology of the surface seems to be reduced and shows a film-like surface as demonstrated by x-ray absorption near edge structure and scanning electron microscopy. As a result of surface functionalization, the energy levels of the semiconductor were shifted toward reductive potentials (by 50 mV) as determined by diffuse reflectance and cyclic voltammetry.

The local-density approximation (LDA)-1/2 technique has been successfully applied to surmount current limitations in density-functional theory to determine excited-states properties of solids via LDAs to the exchange-correlation functional. The main task to properly apply this technique is to choose the “cut-off” radius to truncate the long-ranged self-energy function, originated by the procedure of removing the spurious self-energy of electrons (and/or holes). The usual procedure is by choosing an extreme of the variation of the band gap as a function of this cutoff. This work examines the relationship between that cut-off parameter and the electronegativity difference between cation and anion in binary compounds calculated self-consistently with LDA-1/2.

We propose a surface integral equation simulation scheme which incorporates the integral equation fast Fourier transform accelerative algorithm and domain decomposition method. Such scheme provides efficient and accurate solutions for substrate-supported non-periodic plasmonic array platforms with large number of building blocks and complex element geometry. The effect of array defects can be systematically and successfully studied taking advantage of the considerable flexibility of the domain decomposition approach. The proposed model will be of great advantage for fast and accurate characterization of graded-pattern plasmonic materials and metasurfaces.

We present two straightforward and cost-effective methods, based on metal-assisted chemical etching and a direct imprinting technique, to fabricate metal-covered porous amorphous silicon back reflectors for amorphous silicon solar cells. We demonstrate an increase of approximately 30% in both short-circuit current and overall efficiency with respect to a cell with a flat metal back reflector. This is achieved by implementing light trapping via either a roughened porous amorphous silicon layer or an imprinted periodic grating. This work provides a pathway to increase amorphous silicon solar cell efficiency via increased absorption without significantly impacting processing costs.