scholarly journals Ambient aging effects on the effective energy gap of ZnO thin films

2020 ◽  
Vol 127 (24) ◽  
pp. 245704 ◽  
Author(s):  
G. Bridoux ◽  
G. D. Ruano ◽  
J. M. Ferreyra ◽  
M. Villafuerte
2021 ◽  
pp. 130-137
Author(s):  
Yasir Yahya Kasim ◽  
Ghazwan Ghazi Ali ◽  
Marwan Hafeedh Younus

This work investigates the structural, optical, and surface properties of ZnO thin films prepared by sol-gel method. The effect on waveguide sensor was examined at different irradiation durations of alpha particles. The X-ray diffraction (XRD) measurements revealed that the crystalline phase of ZnO thin films does not change after irradiation and showed a hexagonal structure of wurtzite type with an orientation toward (002). Moreover, ZnO thin films absorbance was increased with increasing irradiation time, whereas the transmittance was decreased. Additionally, increasing the irradiation time of alpha particles caused an increase in the extinction coefficient and the imaginary part,  while the optical energy gap of the ZnO samples was decreased. Finally, the maximum value of sensitivity was 42%, found at 6 min of irradiation duration.


2020 ◽  
Vol 12 (01) ◽  
pp. 66-72
Author(s):  
Qasim Chfat Abdulridha ◽  
◽  
Hussein Ali Noor ◽  

This research included the preparation of (ZnO) thin films by CBD technique for the deposition of chemical bath thickness (150 ± 20nm). X-ray diffraction was analyzed and showed that the films crystallize in a polycrystalline hexagonal structure, with a preferred direction along the level (100). Increased volume of calculated crystals for deposited films was found by increasing molar concentration. The surface morphology of films was studied by SEM, and the surface morphology of ZnO films is a heterogeneous distribution. The optical properties of all deposited ZnO films contained a spectral permeability and absorption spectrum in the wavelength range (300-1100nm), and the transmittance decreased with increasing molar concentration, it was found that the value of the light energy gap (Eg) increases with increasing molecular concentration band gap between 3.1 and 3.2 eV.


2019 ◽  
Vol 15 (32) ◽  
pp. 114-121
Author(s):  
Maysar A. Salim

Zinc Oxide (ZnO) thin films of different thickness were preparedon ultrasonically cleaned corning glass substrate, by pulsed laserdeposition technique (PLD) at room temperature. Since mostapplication of ZnO thin film are certainly related to its opticalproperties, so the optical properties of ZnO thin film in thewavelength range (300-1100) nm were studied, it was observed thatall ZnO films have high transmittance (˃ 80 %) in the wavelengthregion (400-1100) nm and it increase as the film thickness increase,using the optical transmittance to calculate optical energy gap (Egopt)show that (Egopt) of a direct allowed transition and its value nearlyconstant (~ 3.2 eV) for all film thickness (150, 180, 210, and 240)nm, so Zn0 thin films were used as a transparent conducting oxide(TCO) in various optoelectronic application such as a window in athin film solar cells.


2019 ◽  
Vol 17 (43) ◽  
pp. 58-66
Author(s):  
Eman M. Nasir

ZnO thin films have been prepared by pulse laser deposition technique at room temperatures (RT). These films were deposited on GaAs substrate to form the ZnO/GaAs heterojunction solar cell. The effect of annealing temperatures at ( RT,100, 200)K on structural and optical properties of ZnO thin films has been investigated. The X-ray diffraction analysis indicated that all films have hexagonal polycrystalline structure. AFM shows that the grains uniformly distributed with homogeneous structure. The optical absorption spectra showed that all films have direct energy gap. The band gap energy of these films decreased with increasing annealing temperatures.  From the electrical properties, the carriers have n-type conductivity.  From C-V measurement of ZnO/GaAs heterojunciton solar cell at frequency 100, 200 KHz, It is found that built–in potential (Vbi) increases with increase frequency. Also, from I-V characteristic it is observed that the ideality factor is 2.7. Short-circuit current (Isc) is 4.0mA/cm2, open circuit voltage (Voc) is 0.5V, fill factor ( F.F) is 0.7  and the efficiency is about 6.0 %.


Author(s):  
A M Wagh and N U Patil

The objective of this study is to synthesize ZnO nano particles in form thin film on glass substrate and study antibacterial active of such films. ZnO thin films were prepared by spray pyrolysis technique using zinc acetate and isopropyl alcohol as precursor in the temperature range 375̊C to 425̊C. The optical properties of the film were studied on UV/VIS/NIR spectrophotometer. The energy gap of the film is evaluated and it is found to be 3.31 eV. The polycrystalline nature of the ZnO film was confirmed by structural analysis by Xray diffraction method and the grain size is determined. It is found to be 50nm. The electrical resistivity of the film was measured by four probe method at different temperatures and it is found that electrical resistivity varying in the range 103 to 104 Ω–cm. we studied the antibacterial activity of ZnO thin film against gram-negative bacteria. Escherichia coli (E- coli) were used as test micro organisms. It is found that ZnO film enhanced the significant antibacterial activity.


2020 ◽  
Vol 21 (3) ◽  
pp. 433-439
Author(s):  
T. Kiran ◽  
H. M. Parveez Ahmed ◽  
Noor Shahina Begum ◽  
Karthik Kannan ◽  
D. Radhika

Rare earth (RE) ions activated ZnO thin films were prepared via sol-gel route and the thin films be categorized by various techniques. X-ray diffraction (XRD) studies display the hexagonal wurtzite structure of the prepared thin films. Scherrer's formula was utilized to calculate the average crystallite size (25–40 nm) with different Sm3+ concentrations. The optical energy gap was calculated by Diffused Reflectance spectra (DRS). The Acid Red (AR) dye was degraded under ultraviolet (UV) light irradiation with ZnO: Sm3+(1-9 mol %) nanostructured thin films  and the highest photodegradation (95 %) was observed for 7 mol %  of  Sm3+ doped ZnO catalyst. All the obtained results suggest that prepared material could be a prominent material as photocatalyst.


2015 ◽  
Vol 33 (3) ◽  
pp. 491-496 ◽  
Author(s):  
Y. Larbah ◽  
M. Adnane ◽  
T. Sahraoui

Abstract Undoped ZnO thin films have been prepared on glass substrates at different substrate temperatures by spray pyrolysis method. The effect of temperature on the structural, morphological and optical properties of n-type ZnO films was studied. The X-ray diffraction (XRD) results confirmed that the ZnO thin films were polycrystalline with wurtzite structure. Scanning electron microscopy (SEM) measurements showed that the surface morphology of the films changed with temperature. The studies demonstrated that the ZnO film had a transmission of about 85 % and energy gap of 3.28 eV at 450 °C. The RBS measurements revealed that ZnO layers with a thickness up to 200 nm had a good stoichiometry.


2018 ◽  
Vol 25 (01) ◽  
pp. 1850035 ◽  
Author(s):  
NRIPASREE NARAYANAN ◽  
N. K. DEEPAK

Structural, optical and electrical properties of bare and N monodoped ZnO thin films were investigated. The samples were prepared on glass substrates by spray pyrolysis technique. N doping resulted in p type electrical conductivity as evident from the Hall measurement results. XRD analysis confirmed the structural purity of all the films and compositional analysis by energy dispersive X-ray spectroscopy verified the inclusion of N in doped films in addition to Zn and O. Doping resulted in deterioration in crystallinity. Optical transmittance got diminished with doping due to the degradation in crystallinity as well as due to the presence of deep N related defects as evident from the photoluminescence spectra. Optical energy gap red-shifted with doping percentage due to the introduction of impurity levels near the valence band edge within the forbidden gap with acceptor doping.


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