• Transactions on Electrical and Electronic Materials
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• v.16 no.2
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• pp.78-81
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• 2015

Pure ZnO and ZnO nanowires doped with 3 wt.% Ga (‘3GZO’) were grown by pulsed laser deposition in a furnace system. The doping of Ga in ZnO nanowires was analyzed by observing the optical and chemical properties of the doped nanowires. The diameter and length of nanowires were under 200 nm and several ${\mu}m$, respectively. Changes of significant resistance were observed and the sensitivities of ZnO and 3GZO nanowires were compared. The sensitivities of ZnO and 3GZO nanowire sensors measured at 300℃ for 1 ppm of ethanol gas were 97% and 48%, respectively.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11a
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• pp.218-221
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• 2004

The electronic state of ZnO doped with Al, Ga and In, which belong to III family elements in periodic table, was calculated using the density functional theory. In this study, the program used for the calculation on theoretical structures of ZnO and doped ZnO was Vienna Ab-initio Simulation Package (VASP), which is a sort of pseudo potential method. The detail of electronic structure was obtained by the describe variational $X{\alpha}(DV-X{\alpha})$(DV-Xa) method, which is a sort of molecular orbital full potential method. The optimized crystal structures obtained by calculations were compared to the measured structure. The density of state and energy levels of dopant elements was shown and discussed in association with properties.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.7
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• pp.584-588
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• 2011

The ZnO thin films doped with Ga and Ge (GZO:Ge) were prepared on glass substrate using RF sputtering system. Structural, morphological and optical properties of the films deposited in different temperatures were studied. Proportion of the element of using target was 97 wt% ZnO, 2.5 wt% Ga and 0.5 wt% Ge with 99.99% highly purity. Structural properties of the samples deposited in different temperatures with 200 w RF power were investigated by field emission scanning electron microscopy, FE-SEM images and x-ray diffraction XRD analysis. Atomic force microscopy, AFM images were able to show the grain scales and surface roughness of each film rather clearly than SEM images. it was showed that increasing temperature have better surface smoothness by FE-SEM and AFM images. Transmittance study using UV-Vis spectrometer showed that all the samples have highly transparent in visible region (300~800 nm). In addition, it can be able to calculate bandgap energy from absorbance data obtained with transmittance. The hall resistivity, mobility, and optical band gap energy are influenced by the temperature.

• Advances in nano research
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• v.5 no.3
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• pp.193-201
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• 2017

ZnO, ZnO: Cu, Ga, and ZnO: Cu, Ga, Ag thin films were obtained by oxidization of ZnS and ZnS: Cu, Ga films deposited onto glass substrates by electron-beam evaporation from ZnS and ZnS: Cu, Ga targets and from ZnS: Cu, Ga film additionally doped with Ag by the closed space sublimation technique at atmospheric pressure. The film thickness was about $1{\mu}m$. The oxidation was carried out at $600-650^{\circ}C$ in air or in an atmosphere containing water vapor. Structural characteristics were investigated by X-ray diffraction (XRD) and atomic force microscopy (AFM). Photoluminescence (PL) spectra of the films were measured at 30-300 K using the excitation wavelengths of 337, 405 and 457.9 nm. As-deposited ZnS and ZnS: Cu, Ga films had cubic structure. The oxidation of the doped films in air or in water vapors led to complete ZnO phase transition. XRD and AFM studies showed that the grain sizes of oxidized films at wet annealing were larger than of the films after dry annealing. As-deposited doped and undoped ZnS thin films did not emit PL. Shape and intensity of the PL emission depended on doping and oxidation conditions. Emission intensity of the films annealed in water vapors was higher than of the films annealed in the air. PL of ZnO: Cu, Ga films excited by 337 nm wavelength exhibits UV (380 nm) and green emission (500 nm). PL spectra at 300 and 30 K excited by 457.9 and 405 nm wavelengths consisted of two bands - the green band at 500 nm and the red band at 650 nm. Location and intensities ratio depended on the preparation conditions.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.463-465
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• 2005

The $ZnGa_2O_4$:Mn phosphor was synthesized through solid-state reactions at the various molar ratio of Mn from 0.002 % to 0.01 %. Structural and optical properties of the $ZnGa_2O_4$:Mn phosphor was investigated by using X-ray diffraction (XRD), and cathodoluminescence (CL) measurements. The XRD patterns show that the Mn-doped $ZnGa_2O_4$ has a (311) main peak and a spinel phase. Also the emission wavelength shifts from 420 to 510 nm in comparison with $ZnGa_2O_4$ when Mn is doped in $ZnGa_2O_4$. These results indicate that $ZnGa_2O_4$:Mn phosphors hold promise for potential applications in field-emission display devices with high brightness operating in green spectral regions.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.7
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• pp.594-598
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• 2011

We have investigated the sensing properties of ethanol gas sensor with pure ZnO and Ga-doped ZnO nanowires on Au coated (0001) sapphire substrates grown by hot walled pulsed laser deposition. Randomly aligned ZnO nanowires arrays were grown on a Au-electrode patterned under ambient conditions. ZnO nanowires have various sizes and shapes with a different substrate position inside a furnace. The average of length and diameter of the ZnO nanowires were $8\;{\mu}m$ and 100 nm respectively, and confirmed by field emission scanning electron microscopy. Sensitivity chanege characterization of the gas sensor was found that measured sensitivities of the ethanol gas sensors were 83.3% and 68.3% at $300^{\circ}C$ respectively.

• Proceedings of the KIEE Conference
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• 2006.10a
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• pp.46-47
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• 2006

Ga-doped ZnO nanowires have been synthesized by pulsed laser deposition (PLD) in furnace on gold coated (0001) sapphire substrates. The effect of repetition rate on structural and optical properties of Ga-doped ZnO nanowires are investigated. By controlling repetition rate, the diameter of nanowires is varied between about 60 and 100 nm, and the length of nanowires is varied between about 2 and 4 um. The X-ray diffraction (XRD) reveals the structural defects induced by the Ga doping. The room temperature photoluminescence (PL) spectra of Ga-doped ZnO nanowires show strong UV emission between 382.394 and 385.279 nm with negligible visible emission.

• Journal of the Korean Ceramic Society
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• v.35 no.6
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• pp.619-625
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• 1998

Mn doped {{{{ {Zn {Ga }_{2 }O }_{4 } }} thin film phosphors were prepared on Si(100) wafers and ITO coated glass substrates by rf magnetron sputtering technique and the effects of the substrates dopant and the sputtering paramet-ers were analyzed, Changes of the oreintation were observed after annealine tratment. The grain size of {{{{ {Zn {Ga }_{2 }O }_{4 } }} : Mn thin film deposited on Si wafer was smaller than that on ITO/glass substrate which resulted in higher PL intensity. The PL spectra of Mn doped {{{{ {Zn {Ga }_{2 }O }_{4 } }} thin films showed sharp green luminescence spec-trum. According to CL spectrum it could be concluded that Mn ions acted as an actuator for green emission by substituting Zn atom sites.

• Proceedings of the Materials Research Society of Korea Conference
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• 2007.11a
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• pp.56.1-56.1
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• 2007

• Journal of the Korean institute of surface engineering
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• v.42 no.3
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• pp.122-127
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• 2009

Ga/Al doped ZnO (GAZO) thin films were prepared on non-alkali glass substrate by co-sputtering system using two DC cathodes equipped with AZO ($Al_2O_3$:2.0 wt%) target and GZO ($Ga_2O_3$:6.65 wt%) target. This study examined the influence of Al/Ga concentration and substrate temperature on the electrical, structural and optical properties of GAZO films. The lowest resistivity $1.95{\times}10^{-3}{\Omega}cm$ was obtained at room temperature. With increasing substrate temperature, resistivity of GAZO film decreased to a minimum value of $7.47{\times}10^{-4}{\Omega}cm$ at below $300^{\circ}C$. Furthermore, when 0.05% $H_2$ gas was introduced, resistivity of GAZO film decreased to $6.69{\times}10^{-4}{\Omega}cm$. All the films had a preferred orientation along the (002) direction, indicating that the deposited films have hexagonal wurtzite structure formed by the textured growth along the c-axis. The average transmittance of the films was more than 85% in the visible light range.