Band gap control and photoluminescence properties of Ba(Co2x Ti1−x )O3 thin films prepared by Sol–gel method

2014 ◽  
Vol 117 (2) ◽  
pp. 917-926 ◽  
Author(s):  
Anchal Srivastava ◽  
Kamakhya Prakash Misra
Keyword(s):  
Thin Films ◽  
Band Gap ◽  
Sol Gel ◽  
Photoluminescence Properties ◽  
Gel Method ◽  
Sol Gel Method ◽  
Gap Control

EFFECT OF ANNEALING TEMPERATURE ON OPTICAL PROPERTIES OF TITANIUM DIOXIDE THIN FILMS PREPARED BY SOL-GEL METHOD

2012 ◽  
Vol 06 ◽  
pp. 13-18 ◽  
Author(s):  
M. T. SARODE ◽  
P. N. SHELKE ◽  
S. D. GUNJAL ◽  
Y. B. KHOLLAM ◽  
M. G. TAKWALE ◽  
...  
Keyword(s):  
Thin Films ◽  
Optical Properties ◽  
Band Gap ◽  
Annealing Temperature ◽  
Optical Measurement ◽  
Sol Gel ◽  
Fesem Image ◽  
Gel Method ◽  
Sol Gel Method ◽  
Crystallite Sizes

TiO 2 thin films were deposited on glass substrates by sol-gel method. Nanocrystalline TiO 2 thin films were prepared at ambient conditions and titanium tetraisopropoxide [ C 12 H 28 O 4 Ti ] was used as a Ti -precursor. The effect of annealing temperature on optical properties of nanocrystalline TiO 2 thin films was studied. The as-deposited films were dried at 100 °C for 1 hr. The films formed were further heated in temperature between 200 and 500 °C for 1 hr. The films were characterized by different techniques: XRD, UV-visible spectroscopy, FTIR spectroscopy and FESEM. The characterization studies revealed that the films are crystallized as anatase phase and nano-structured with better optical properties α = 0.89 as compared to reported data. The optical measurement showed the indirect band gap between 3.31 and 3.35 eV with corresponding crystallite sizes between 8.9 and 3.7 nm. The FESEM image of film annealed at 400 °C showed spherical nanocrystalline structure of TiO 2 particles. The crystallite sizes obtained from FESEM image are found to be between 30 and 100 nm. It is also observed that refractive index of the film increases with increasing the annealing temperature. The smaller crystallite size gives larger band gap due to quantum size effects.

scholarly journals The Microstructure, Electric, Optical and Photovoltaic Properties of BiFeO3 Thin Films Prepared by Low Temperature Sol–Gel Method

Materials ◽  
2019 ◽  
Vol 12 (9) ◽  
pp. 1444 ◽  
Author(s):  
Jiaxi Wang ◽  
Li Luo ◽  
Chunlong Han ◽  
Rui Yun ◽  
Xingui Tang ◽  
...  
Keyword(s):  
Thin Films ◽  
Low Temperature ◽  
Band Gap ◽  
Annealing Temperature ◽  
Photovoltaic Effect ◽  
Sol Gel ◽  
Photovoltaic Properties ◽  
Gel Method ◽  
X Ray ◽  
Sol Gel Method

Ferroelectrics have recently attracted attention as a candidate class of materials for use in photovoltaic devices due to their abnormal photovoltaic effect. However, the current reported efficiency is still low. Hence, it is urgent to develop narrow-band gap ferroelectric materials with strong ferroelectricity by low-temperature synthesis. In this paper, the perovskite bismuth ferrite BiFeO3 (BFO) thin films were fabricated on SnO2: F (FTO) substrates by the sol–gel method and they were rapidly annealed at 450, 500 and 550 °C, respectively. The microstructure and the chemical state’s evolution with annealing temperature were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS), and the relationship between the microstructure and electric, optical and photovoltaic properties were studied. The XRD, SEM and Raman results show that a pure phase BFO film with good crystallinity is obtained at a low annealing temperature of 450 °C. As the annealing temperature increases, the film becomes more uniform and has an improved crystallinity. The XPS results show that the Fe3+/Fe2+ ratio increases and the ratio of oxygen vacancies/lattice oxygen decreases with increasing annealing temperature, which results in the leakage current gradually being reduced. The band gap is reduced from 2.68 to 2.51 eV due to better crystallinity. An enhanced photovoltaic effect is observed in a 550 °C annealed BFO film with a short circuit current of 4.58 mA/cm2 and an open circuit voltage of 0.15 V, respectively.

scholarly journals Structural and Optical Properties of ZnO Thin Films Prepared by Molecular Precursor and Sol–Gel Methods

Crystals ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 132 ◽  
Author(s):  
Theopolina Amakali ◽  
Likius. S. Daniel ◽  
Veikko Uahengo ◽  
Nelson Y. Dzade ◽  
Nora H. de Leeuw
Keyword(s):  
Thin Films ◽  
Optical Properties ◽  
Band Gap ◽  
Optical Band Gap ◽  
Sol Gel ◽  
Zno Thin Films ◽  
Structural And Optical Properties ◽  
Gel Method ◽  
Sol Gel Method ◽  
Molecular Precursor

Zinc oxide (ZnO) is a versatile and inexpensive semiconductor with a wide direct band gap that has applicability in several scientific and technological fields. In this work, we report the synthesis of ZnO thin films via two simple and low-cost synthesis routes, i.e., the molecular precursor method (MPM) and the sol–gel method, which were deposited successfully on microscope glass substrates. The films were characterized for their structural and optical properties. X-ray diffraction (XRD) characterization showed that the ZnO films were highly c-axis (0 0 2) oriented, which is of interest for piezoelectric applications. The surface roughness derived from atomic force microscopy (AFM) analysis indicates that films prepared via MPM were relatively rough with an average roughness (Ra) of 2.73 nm compared to those prepared via the sol–gel method (Ra = 1.55 nm). Thin films prepared via MPM were more transparent than those prepared via the sol–gel method. The optical band gap of ZnO thin films obtained via the sol–gel method was 3.25 eV, which falls within the range found by other authors. However, there was a broadening of the optical band gap (3.75 eV) in thin films derived from MPM.

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