Laboratoire Of Photovoltaiques Du Center Des Recherches Et Des Technologies Of Lenergie

Hammam-Lif, Tunisia

Laboratoire Of Photovoltaiques Du Center Des Recherches Et Des Technologies Of Lenergie

Hammam-Lif, Tunisia
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Boutchich M.,Supelec | Arezki H.,Supelec | Alamarguy D.,Supelec | Ho K.-I.,Chang Gung University | And 8 more authors.
Applied Physics Letters | Year: 2014

Large-area graphene film doped with nitrogen is of great interest for a wide spectrum of nanoelectronics applications, such as field effect devices, super capacitors, and fuel cells among many others. Here, we report on the structural and electronic properties of nitrogen doped trilayer graphene on 4H-SiC (0001) grown under atmospheric pressure. The trilayer nature of the growth is evidenced by scanning transmission electron microscopy. X-ray photoelectron spectroscopy shows the incorporation of 1.2% of nitrogen distributed in pyrrolic-N, and pyridinic-N configurations as well as a graphitic-N contribution. This incorporation causes an increase in the D band on the Raman signature indicating that the nitrogen is creating defects. Ultraviolet photoelectron spectroscopy shows a decrease of the work function of 0.3 eV due to the N-type doping of the nitrogen atoms in the carbon lattice and the edge defects. A top gate field effect transistor device has been fabricated and exhibits carrier mobilities up to 1300 cm2/V s for holes and 850 cm2/V s for electrons at room temperature. © 2014 AIP Publishing LLC.


Ben Naceur J.,Laboratoire Of Photovoltaiques Du Center Des Recherches Et Des Technologies Of Lenergie | Gaidi M.,Laboratoire Of Photovoltaiques Du Center Des Recherches Et Des Technologies Of Lenergie | Bousbih F.,Laboratoire Of Photovoltaiques Du Center Des Recherches Et Des Technologies Of Lenergie | Mechiakh R.,Laboratoire Of Photovoltaiques Du Center Des Recherches Et Des Technologies Of Lenergie | And 2 more authors.
Current Applied Physics | Year: 2012

In this paper we report on the effect of annealing on the microsctructural and optoelectronic properties of titanium dioxide (TiO2) thin films prepared using sol-gel method onto silicon (Si) (100) and quartz substrates. The annealing temperatures range from 200 to 1000 °C. The Microstructural properties of annealed thin films were investigated by Thermal gravimetric analyses (TGA), X-ray diffraction (XRD) and Raman Spectroscopy. The surface morphology of the film was examined using Atomic Force Microscopy (AFM) method. The optical properties of TiO2 thin films were characterized using UV-VIS and Spectroscopic ellipsometry. The results have shown that the TiO 2 thin films persist in the anatase phase even after annealing at 800 °C. The phase transformation from anatase to rutile occurred only when the films were annealed at 1000 °C. AFM studies revealed nanocrystalline structure where their shape and density depend strongly on the annealing temperatures. The elaborated nanostructured-TiO2 thin films present a high transparency in the visible range. Spectroscopic ellipsometry (SE) study was used to determine the effect of annealing temperature on the thickness and on the optical constant of TiO2 thin films. Spectroscopic ellipsometry and UV-VIS shows that the band gap of TiO2 thin films was found to decrease when the annealing temperature increases. The Anatase phase was find to show higher photocatalytic activity than the rutile one. © 2011 Elsevier B.V. All rights reserved.

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