Temperature resistance coefficient of doped with rare earth elements nanostructured silicon films

The regularities of changes in the concentration of an electrically active dopant in a nanostructured silicon film by changing the electrical resistivity depending on the doping conditions were investigated. The dependences of the changes in the obtained structures doped with rare-earth elements, such as La, Eu, Sm, Dy, Gd (lanthanides), on nanostructured silicon films are determined. The regularities of the obtained films changes and the temperature coefficient of resistance (TCR) change depending on the formation conditions are established. The regularities of the TCR are shown depending on the selected conditions for doping or non-doping of nanostructured silicon films with various impurities. It is shown that the main conditions under which the effect and change in the temperature coefficient of resistors resistance on thin films using rare-earth elements, such as oxygen, boron and phosphorus in the bulk of the film, is considered to be the temperature effect after deposition.

Wide-angle Reconfigurable Refraction by Silicon Fourier Metasurfaces

We design metasurfaces based on silicon films with smooth relief described by several Fourier harmonics and study their ability to redirect the refracted light over a wide angular range controlled by subtle variations of the optical setup. We use semi-analytical approach based on the Rayleigh hypothesis as well as full-scale numerical solutions to optimize the relief shape. To illustrate the reconfigurability potential, we design metasurfaces efficiently redirecting the refracted light from 83° to −73° with respect to the normal, when the angle of incidence is varied from 0° to 2°, and from 80° to −74°, when the substrate permittivity is altered from 2.3 to 2.2.

Aluminum diffusion during laser-stimulated crystallization of thin silicon films

Diffusion of aluminum in amorphous silicon films during crystallization through infrared laser irradiation was studied. Diffusion regime was found to change from limited source to abundant source diffusion at higher laser source power. At the same time, crystalline structure of the obtained samples becomes more perfect, which is more characteristic to limited source diffusion mode.

Boron Induced Crystallization of Silicon Oon Glass: An Alternate Way to Crystallize Amorphous Silicon Films for Solar Cells

Demand for efficient window layer in thin film solar cells with high crystallinity is ever increasing that finds important application in multi-junction/tandem silicon solar cells. Doping of diborane (B2H6) in hydrogenated silicon films using plasma discharge decomposition of silane (SiH4) and (B2H6) gases were analyzed. The boron flow (FB) to silane ratio was varied from 0–0.30. Variation in film characteristics with B2H6 gas-phase ratio were analyzed, and concluded that doping boron induces crystallization in hydrogenated amorphous silicon (a-Si: H) film structure. The Raman and field emission scanning electron spectroscopy (FESEM) confirmed the boron induced crystallinity effect in silicon films at different diborane flow. The results showed that as boron content increases beyond certain ratio, silicon crystallization suppresses and the crystallite sizes were also reduced. From results, it was observed that crystallinity in FB = 0.05 is 79 % and decreases to 77 % when films are slightly higher doped (FB = 0.10) and further decreases when the films were heavily doped. These results validate that boron suppresses silicon crystallization due to local deformations caused by the impurities. Infra-red absorption studies and their analysis also confirm the crystallization in boron doped films with additional band appears at ~ 611 cm− 1. This band is named as boron induced crystallinity mode of vibrational spectra. The estimated hydrogen content (CH) decreases confirmed crystallinity in the silicon structure with boron doping. Further, the energy dispersive spectroscopy (EDX) indicates the presence of boron and other impurities in deposited silicon films. The effect of boron on crystallinity and crystallite size as well as the mechanism were presented in detailed.