Effects of sputtering power and pressure on properties of ZnO:Ga thin films prepared by oblique-angle deposition (original) (raw)
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Thin Solid Films, 2003
Highly conducting and transparent gallium doped zinc oxide thin films have been deposited at high growth rates by r.f. magnetron sputtering at room temperature on inexpensive soda lime glass substrates. The argon sputtering pressure was varied between 0.15 and 2.1 Pa. The lowest resistivity was 2.6=10 V cm (sheet resistance f6 Vysq. for a thickness f600 nm) and y4 was obtained at an argon sputtering pressure of 0.15 Pa and a r.f. power of 175 W. The films present an overall transmittance in the visible spectra of approximately 90%. The increase on the resistivity for higher sputtering pressures is due to a decrease of both, mobility and carrier concentration, and is associated to a change on the surface morphology. The low resistivity, accomplished with a high growth rate (290 Aymin) and with a room temperature deposition enables these films deposition onto polymeric substrates for flexible optoelectronic devices. ᮊ
2016
Gallium (Ga)-doped zinc oxide (ZnO:Ga) thin films were deposited on corning glass substrates by homemade DC magnetron sputtering. Effects of argon gas pressure on the structural and optical properties of ZnO:Ga thin films were investigated by XRD, SEM and UV-Vis spectroscopy. The argon gas pressure was adjusted at 450, 500 and 550 mtorr. All the films exhibit a strong (002) peak and a weak (004) peaks. The XRD pattern demonstrated that crystallinity of the film improved with increasing of the argon pressure. ZnO:Ga thin films deposited have polycrystalline structure. It was shown that the argon pressure has a great influence on ZnO:Ga film surface structures. The grain size of the films was increased with the increases of argon pressure. The grains shape of the film change from an equiaxed rough grain to a longish grain with the argon pressure. The average of transmittance of the films is about 80% in the visible range. It is shown that the argon pressure has no effect significantly on optical bandgap of ZnO:Ga, but in general it can be explained that increasing of the argon pressure can reduce the bandgap. The optical bandgap of ZnO:Ga thin films in the range of 3.25-3.3 eV.
Journal of Crystal Growth, 2005
Gallium-doped zinc oxide (ZnO:Ga) films were prepared on glass substrates by r.f. magnetron sputtering at low substrate temperature. Structural, electrical and optical properties of the ZnO:Ga films were investigated in terms of the preparation conditions. The obtained films were polycrystalline with a hexagonal wurtzite structure and preferentially oriented in the (0 0 2) crystallographic direction. The transmittance of the ZnO:Ga films in the visible range was over 85%. The lowest resistivity and sheet resistance for the ZnO:Ga films were about 3.9 Â 10 À4 O cm and 4.6 O/&, respectively.
Gallium (Ga)-doped zinc oxide (ZnO:Ga) thin films were deposited on corning glass substrates by homemade DC magnetron sputtering. Effects of argon gas pressure on the structural and optical properties of ZnO:Ga thin films were investigated by XRD, SEM and UV-Vis spectroscopy. The argon gas pressure was adjusted at 450, 500 and 550 mtorr. All the films exhibit a strong (002) peak and a weak (004) peaks. The XRD pattern demonstrated that crystallinity of the film improved with increasing of the argon pressure. ZnO:Ga thin films deposited have polycrystalline structure. It was shown that the argon pressure has a great influence on ZnO:Ga film surface structures. The grain size of the films was increased with the increases of argon pressure. The grains shape of the film change from an equiaxed rough grain to a longish grain with the argon pressure. The average of transmittance of the films is about 80% in the visible range. It is shown that the argon pressure has no effect significantly on optical bandgap of ZnO:Ga, but in general it can be explained that increasing of the argon pressure can reduce the bandgap. The optical bandgap of ZnO:Ga thin films in the range of 3.25-3.3 eV.
Journal of Natural Sciences and Mathematics Research
ZnO:Ga thin films grown on a corning glass substrate by the DC Magnetron Sputtering method have been successfully grown. The purpose of this study was to study the effect of plasma power on the resulting thin film structure. The quality and structure of the films were studied using X-ray duffraction (XRD), and scanning electron microscopy (SEM). Based on XRD characterization, it was found that the ZnO:Ga thin film has a hexagonal wurtize structure on the C-axis with orientation planes (002) and (101). The quality of the resulting thin films can also be seen from the value of full-width at half maximum (FWHM) in the orientation plane (002) which increases with increasing plasma power during the growth process from 0.13°- 0.16°. The larger the FWHM value, the smaller the crystal grain size so that the structure becomes less good. This is supported by the surface morphology of the film which is less dense when the plasma power increases. ©2018 JNSMR UIN Walisongo. All rights reserved.
Effect of annealing on properties of sputtered and nitrogen-implanted ZnO:Ga thin films
EPJ Photovoltaics, 2012
Thin films of gallium-doped zinc oxide (ZnO:Ga) were deposited on Corning glass substrates by rf diode sputtering and then implanted with 180 keV nitrogen ions in the dose range of 1×10 15 ÷ 2×10 16 cm −2. After the ion implantation, the films were annealed under oxygen and nitrogen ambient, at different temperatures and time, and the effect on their microstructure, type and range of conductivity, and optical properties was investigated. Post-implantation annealing at 550 • C resulted in n-type conductivity films with the highest electron concentration of 1.4 × 10 20 cm −3. It was found that the annealing parameters had a profound impact on the film's properties. A p-type conductivity (a hole concentration of 2.8 × 10 19 cm −3 , mobility of 0.6 cm 2 /V s) was observed in a sample implanted with 1 × 10 16 cm −2 after a rapid thermal annealing (RTA) in N2 at 400 • C. Optical transmittance of all films was >84% in the wavelength range of 390-1100 nm. The SIMS depth profile of the complex 30 NO − ions reproduces well a Gaussian profile of ion implantation. XRD patterns reveal a polycrystalline structure of N-implanted ZnO:Ga films with a c-axis preferred orientation of the crystallites. Depending on the annealing conditions, the estimated crystallite size increased 25 ÷ 42 nm and average micro-strains decreased 1.19 × 10 −2 ÷ 6.5 × 10 −3 respectively.
Influence of annealing time on the morphology and oxygen content of ZnO:Ga thin films
Journal of Physics: Conference Series, 2019
The effect of annealing time on the morphology and oxygen content of ZnO:Ga films has been deeply studied. ZnO:Ga films were grown with the use of the dc Magnetron Sputtering on the corning glass substrate. The films are grown with a plasma power of 30 watt, Argon gas pressure of 500 mtorr, and a substrate temperature of 300 °C for an hour deposition. The effect of annealing time on the morphology of ZnO:Ga films was observed by using Scanning Electron Microscope (SEM), whereas the oxygen content of the film was determined by Energy Dispersive X-ray (EDX) spectrometers. The SEM images showed that the ZnO:Ga film grown with an annealing time of 40 minutes possess relatively more homogeneous and compact morphology with smoother grain size than the ZnO:Ga films that deposited with annealing times of 30 and 50 minutes. The EDX results confirmed that this film possess lowest oxygen content (24.5 % of mass) but highest Ga content (1.7 % of mass) comparated to the ZnO:Ga thin films grown w...
Impact of sputtering power on the properties of Al and Ga co-sputtered ZnO thin films
Journal of Materials Science: Materials in Electronics, 2015
In the current study three sets of Aluminum and Gallium co-sputtered Zinc Oxide films were grown with varying sputtering power (100, 200 and 300 W) on soda lime glass substrate using DC sputtering. Aluminum doped ZnO (Al 2 O 3 2 wt%), Gallium doped ZnO (Ga 2 O 3 2 wt%) sputtering targets were used. The thickness ratio of Al doped ZnO and Ga doped ZnO (1:1) was maintained same in all the Al and Ga co-sputtered (ZAG) thin films. Optical absorption data reveals the high transmission for the as grown films which achieved a maximum value of nearly 90 % in visible spectra for the 100 W deposited ZAG film. The XRD graph indicates a (002) preferred growth with other weak peaks at (102) and (103). This confirms the polycrystalline nature of the film. Intense peak is observed corresponding to (002) phase which implies a better crystallite size for the 300 W grown ZAG film. XRD results suggest that with increasing sputtering power the crystallite size shows an increasing trend. Hall Effect Measurement system was used to measure the electrical properties viz. carrier concentration, resistivity and mobility of the ZAG films. Lowest resistivity value of 5.46 9 10-4 X cm was obtained for the ZAG film deposited at sputtering power of 300 W. It was revealed from the obtained data with increasing sputtering power the resistivity value decreased and in the scale of 10-3 to 10-4 X cm with high optical transmittance.
American Journal of Applied Sciences
ZnO:Ga thin films were deposited on corning glass by dc magnetron sputtering. Influence of Ga-doped concentrations on the structural and optical properties of ZnO:Ga thin films were investigated. The XRD patterns show that the crystallinity of deposited films improved with the increase of Ga concentrations from 1 to 2%, then decrease at 3% Ga concentrations. The optical transmittance of films with 1% and 2% Ga concentration reach 85% in the visible range, while at 3% Ga concentration the transmittance of film only 70%. We observed that the band gap of film change due to the addition of Ga dopant. The band gap of the films are 3.27, 3.28 and 3.21 eV for 1, 2 and 3% Ga-doped concentrations, respectively.
XPS analysis of ZnO:Ga films deposited by magnetron sputtering: Substrate bias effect
Applied Surface Science, 2018
This work focuses on X-ray photoelectron spectroscopy (XPS) and combined Raman and photoluminescence experiments performed on ~500 nm thick ZnO:Ga films deposited by magnetron sputtering. The substrate bias voltage applied during the deposition was varied between 0 V (grounded) and-120 V in order to study the effect of Ga-doping on the ZnO wurtzite structure of the films and its electrical properties, when using a fixed doped composition of Ga 2 O 3 (4.5 wt.%) in the ZnO sputtering target. XPS analysis revealed that ZnO dominates in all samples, while the Ga amount is the highest (~2.9 at.%) for a substrate bias polarization of-60 V, diminishing substantially for either decreasing or increasing substrate polarizations. This increase in Ga concentration is responsible for the enhancement of electronic transport properties, resulting in a minimum electrical resistivity of ~300 µΩ.cm. Moreover, the atomic layers closer to the surface are deficient in zinc for higher bias, due to the etching effect of Ar + ions and subsequent Zn re-evaporation. From the Raman experiments, it was observed that the dynamics of the A 1 and E 1 phonons correlates with the decrease of the electrical resistivity. Photoluminescence studies revealed two broad bands, being one near the ZnO near-band-edge (3.4 eV) and another at higher energies (~ 3.6 eV). The band centered at higher energies is more prominent for the case of the more electrically-conductive films, and is ascribed to electron transitions from the conduction band to single ionized oxygen vacancies. The lifetime of the polar-nature longitudinal optical phonons is in the range of 0.1-0.2 ps, which is quite small due to the Fröhlich interactions with gallium dopant atoms and other defects.