Wyniki wyszukiwania - BazTech

1

High transparency and conductivity of heavily In-doped ZnO thin films deposited by dip-coating method

Benzitouni S., Zaabat M., Mahdjoub A., Benaboud A., Boudine B.

Materials Science Poland

|

2018

|

Vol. 36, No. 3

427--434

EN

Heavily In doped zinc oxide (IZO) thin films were deposited on glass substrates by dip-coating method with different concentrations of indium. The effect of heavy In doping on the structural, morphological, optical and electrical properties of ZnO was discussed on the basis of XRD, AFM, UV-Vis spectra and Hall effect measurements. The diffraction patterns of all deposited films were indexed to the ZnO wurtzite structure. However, high In doping damaged the films crystallinity. The highest optical transmittance observed in the visible region (>93 %) exceeded that of ITO: the absolute rival of the most commercial TCOs. The grain size significantly decreased from 140 nm for undoped ZnO to 17.1 nm for IZO with the greatest In ratio. The roughness decreased with increasing In atomic ratio, indicating an improvement in the surface quality. Among all synthesized films, the sample obtained with 11 at.% indium showed the best TCO properties: the highest transmittance (93.5 %) and the lowest resistivity (0.41 Wcm) with a carrier concentration of 2.4 × 1017 cm-3. These results could be a promising solution for possible photonic and optoelectronic applications.

2

Optical properties of porous Si/PECVD SiNx:H reflector on single crystalline Si for solar cells

Remache L., Nychyporuk T., Guermit N., Fourmond E., Mahdjoub A., Lemiti M.

Materials Science Poland

|

2016

|

Vol. 34, No. 1

94--100

EN

The improvement of optical confinement on the back crystalline silicon solar cell is one of the factors leading to its better performance. Porous silicon (PS) layer can be used as a back reflector (BR) in solar cells. In this work, single layers of porous silicon were grown by electrodeposition on a single crystalline silicon substrate. The measurement of the total reflectivity (RT) on Si/PS surface showed a significant improvement in optical confinement compared to that measured on Si/standard Al back surface field (BSF). The internal reflectivity (RB) extracted from total reflectivity measurements achieved 86 % for the optimized single PS layer (92 nm thick layer with 60 % porosity) in the wavelength range between 950 and 1200 nm. This improvement was estimated as more than 17 % compared to that measured on the surface of Si/BSF Al contact. To improve the stability and passivation properties of PS layer BR, silicon nitride layer (SiNx) was deposited by PECVD on a PS layer. The maximum measured total reflectivity for PS/SiNx achieved approximately 56 % corresponding to an improved RB of up to 83 %. The PS formation process in combination with the PECVD SiNx, can be applied in the photovoltaic cell technology and offer a promising technique to produce high-efficiency and low-cost c-Si solar cells.

3

New designs for graded refractive index antireflection coatings

Mahdjoub A., Zighed L.

Engineering Transactions

|

2005

|

Vol. 53, iss. 2

185-196

EN

The constant progress in thin layers technology, especially the graded index inhomogeneous dielectrics, allows the realization of antireflection coatings (ARC) that are less sensitive to thickness and to the incidence angle. Graded refractive index silicon oxynitrides are deposited by Electron Cyclotron Resonance Plasma-Enhanced Chemical Vapor Deposition (ECR-PECVD) controlled in-situ by monochromatic ellipsometry. While avoiding the complexity of the classical multilayer ARCs, the obtained AR coatings permit to obtain the same performances, or furthermore to improve the cells efficiency. Different suggested profiles are optimized by simulation, then they are realized and characterized by spectroscopic ellipsometry and reflectance measurement. The photogenerated current can be enhanced by 45%, and weighted reflectance (between 300 and 1100 nm) reduced to 5.6%. The passivating properties of oxinitrides recommend the use of these AR coatings on texturized surfaces. The weighted reflectance would decrease to less than 1% and short-circuit current will thus be enhanced by 52.79%.