Inter-electrode separation induced amorphous-to-nanocrystalline transition of hydrogenated silicon prepared by capacitively coupled RF PE-CVD technique

Role of inter-electrode spacing in capacitively coupled radio frequency plasma enhanced chemical vapor deposition deposition (PE-CVD) system was studied. The influence of inter-electrode separation on the structural, optical and electrical properties of the deposited films was carefully invesigated keeping all other deposition parameters constant. The results indicate that the film growth rate critically depends up on the plasma chemistry/gas phase chemistry altered by variation of interelectrode separation. Structure and optical properties are strongly influenced by interelectrode separation. The nanocrystallization in the material was observed for smaller inter-electrode separation, whereas higher inter-electrode separation favors amorphous structure of the deposited material. The band gap of the material was found to decrease from ~2 eV to 1.8 eV when inter-electrode separation was varied from 15 mm to 40 mm. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/2200

Evolution of microstructure and opto-electrical properties in boron doped nc-Si:H films deposited by HW-CVD method

Demand for an efficient window layer for a-Si:H based solar cells in terms of electrical conductivity and optical band gap is ever increasing since the inception of single junction and tandem solar cells. In this paper, we report synthesis of highly conducting boron doped p-type nc-Si:H films by HW-CVD using the mixture of silane (SiH4) and diborane (B2H6) without hydrogen (H2) dilution. Variation in film characteristics with B2H6 gas-phase ratio was studied, and revealed that the boron doping induces amorphization in nc-Si:H film structure. The AFM analysis show increase in rms surface roughness and micro-void density while FTIR spectroscopy analysis show shift of hydrogen bonding from Si–H2 and (Si–H2)n complexes to Si–H configuration on boron doping. The hydrogen content was found <2.66 at.% while the band gap remain as high as 1.8 eV or more. At optimized B2H6 gas-phase ratio, we have obtained p-type nc-Si:H films having high band gap (∼2.0 eV), high dark conductivity (∼1.2 S/cm) with low hydrogen content (∼1.78 at.%) at reasonably high deposition rate (∼9.2 Å/s). The obtained films can be used as a window layer in a-Si:H based p–i–n and tandem solar cells and color light detectors

Strain and electric field control of magnetic and electrical transport properties in a magneto elastically coupled Fe3O4 BaTiO3 001 heterostructure

We present a study of the control of electric field induced strain on the magnetic and electrical transport properties in a magnetoelastically coupled artificial multiferroic Fe3O4 BaTiO3 heterostructure. In this Fe3O4 BaTiO3 heterostructure, the Fe3O4 thin film is epitaxially grown in the form of bilateral domains, analogous to a c stripe domains of the underlying BaTiO3 001 substrate. By in situ electric field dependent magnetization measurements, we demonstrate the extrinsic control of the magnetic anisotropy and the characteristic Verwey metal insulator transition of the epitaxial Fe3O4 thin film in a wide temperature range between 20 300 K, via strain mediated converse magnetoelectric coupling. In addition, we observe strain induced modulations in the magnetic and electrical transport properties of the Fe3O4 thin film across the thermally driven intrinsic ferroelectric and structural phase transitions of the BaTiO3 substrate. In situ electric field dependent Raman measurements reveal that the electric field does not significantly modify the antiphase boundary defects in the Fe3O4 thin film once it is thermodynamically stable after deposition and that the modification of the magnetic properties is mainly caused by strain induced lattice distortions and magnetic anisotropy. These results provide a framework to realize electrical control of the magnetization in a classical highly correlated transition metal oxid

Evolution of structural and optical properties of rutile TiO2 thin films synthesized at room temperature by chemical bath deposition method

Nanocrystalline thin films of TiO2 were prepared on glass substrates from an aqueous solution of TiCl3 and NH4OH at room temperature using the simple and cost-effective chemical bath deposition (CBD) method. The influence of deposition time on structural, morphological and optical properties was systematically investigated. TiO2 transition from a mixed anatase–rutile phase to a pure rutile phase was revealed by low-angle XRD and Raman spectroscopy. Rutile phase formation was confirmed by FTIR spectroscopy. Scanning electron micrographs revealed that the multigrain structure of as-deposited TiO2 thin films was completely converted into semi-spherical nanoparticles. Optical studies showed that rutile thin films had a high absorption coefficient and a direct bandgap. The optical bandgap decreased slightly (3.29–3.07 eV) with increasing deposition time. The ease of deposition of rutile thin films at low temperature is useful for the fabrication of extremely thin absorber (ETA) solar cells, dye-sensitized solar cells, and gas sensors

Evolution of structural and optical properties of rutile TiO2 thin films synthesized at room temperature by chemical bath deposition method

Nanocrystalline thin films of TiO2 were prepared on glass substrates from an aqueous solution of TiCl3 and NH4OH at room temperature using the simple and cost-effective chemical bath deposition (CBD) method. The influence of deposition time on structural, morphological and optical properties was systematically investigated. TiO2 transition from a mixed anatase–rutile phase to a pure rutile phase was revealed by low-angle XRD and Raman spectroscopy. Rutile phase formation was confirmed by FTIR spectroscopy. Scanning electron micrographs revealed that the multigrain structure of as-deposited TiO2 thin films was completely converted into semi-spherical nanoparticles. Optical studies showed that rutile thin films had a high absorption coefficient and a direct bandgap. The optical bandgap decreased slightly (3.29–3.07 eV) with increasing deposition time. The ease of deposition of rutile thin films at low temperature is useful for the fabrication of extremely thin absorber (ETA) solar cells, dye-sensitized solar cells, and gas sensors