• Proceedings of the Materials Research Society of Korea Conference
• /
• 2011.05a
• /
• pp.243.2-243.2
• /
• 2011

ZnO materials with a wide band gap of approximately 3.3 eV has been used in transparent conducting oxides (TCO) due to exhibitinga high optical transmission, but its low conductivity acts as role of a limitation for conducting applications. Recently, Ga or Al-doped ZnO (GZO, AZO) becomes transparent conducting materials because of high optical transmission and excellent conductivity. However, the fundamental mechanism underlying the improvement of electrical conductivity of the GZO is still the subject of debate. In this study, we have fully investigated the reasons of high conductivity through the characterization of plane defects, crystal orientation, doping contents, crystal structure in Zn1-xGaxO (x=0, 3, 5.1, 5.6, 6.6 wt%). We manufactured Zn1-xGaxO by sintering ZnO and Ga2O3 powers, having a theoretical density of 99.9% and homogeneous Ga-dopant distribution in ZnO grains. The GZO containing 5.6 wt% Ga represents the highest electrical conductivity of $7.5{\times}10^{-4}{\Omega}{\cdot}m$. In particular, many twins and superlattices were induced by doping Ga in ZnO, revealed by X-ray diffraction measurements and TEM (transmission electron microscopy) observations. Twins developed in conventional ZnO crystal are generally formed at (110) and (112) planes, but we have observed the twins at (113) plane only, which is the first report in ZnO material. Interestingly, the superlattice structure was not observed at the grains in which twins are developed and the opposite case was true. This structural change in the GZO resulted in the difference of electrical conductivity. Enhancement of the conductivity was closely related to the extent of Ga ordering in the GZO lattice. Maximum conductivity was obtained at the GZO with a superlattice structure formed ideal ordering of Ga atoms.

• Proceedings of the Materials Research Society of Korea Conference
• /
• 2007.11a
• /
• pp.139.2-139.2
• /
• 2007

• Advances in Energy Research
• /
• v.4 no.4
• /
• pp.275-284
• /
• 2016

In the present work, ZnO nanoparticles (NPs) have been dispersed alone in the same solvent of the active layer for improving performance parameters of the organic solar cells. Different concentrations of the ZnO NPs have been blended inside active layer of the solar cell based on poly(3-hexylthiophene) (P3HT), which forms the hole-transport network, and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM), which forms the electron-transport network. In the present investigations, the ZnO NPs may represent an efficient tool for improving light harvesting through light scattering inside active layer, electron mobility, and electron acceptance strength which tend to improve photocurrent and performance parameters of the investigated solar cell. The fill factor (FF) of the ZnO-doped solar cell increases nearly 14% compared to the non-doped solar cell when the doping is 50%. The present investigations show that ZnO NPs improve power conversion efficiency of the solar cell from 1.23% to 1.64% with increment around 25% that takes place after incorporation of 40% as a volume ratio of the ZnO NPs inside P3HT:PCBM active layer.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2005.07a
• /
• pp.432-433
• /
• 2005

In this study, Al doped ZnO(AZO) thin film were prepared on glass substrates by FTS(Facing Targets Sputtering) system. We investigated electrical, optical and structural properties of AZO thin film with the substrate temperature of the R.T, $100^{\circ}C$, $200^{\circ}C$ and the post-annealing. The crystallinity of AZO thin film was increased with increasing the substrate temperature and post-annealing temperature $600^{\circ}C$. The remarkable change of the resistivity with the substrate temperature didn't found and the resistivity with post-annealing was increased slightly.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.22 no.11
• /
• pp.36-43
• /
• 2008

In this parer aluminium-doped zinc oxide(ZnO:Al) conducting layer was deposited on polyethylene terephthalate(PET) substrate by r. f. magnetron sputtering method. The effects of gas pressure and r. f. sputtering power on the structural and electrical properties of ZnO:Al thin film were investigated experimentally. Especially the effect of position of PET substrate on the electrical properties of the film was studied and fixed to improve the electrical properties and also to increase the deposition rate. The results show that the structural and electrical properties of ZnO:Al thin film were strongly influenced by the gas pressure and sputtering power. The minimum resistivity of $1.1{\times}10^{-3}[{\Omega}-cm]$ was obtained at 5[mTorr] of gas pressure, and 18D[W] of sputtering power. The deposition rate of ZnO:Al film at 5[mTorr] of gas pressure was 248[nm/min]. and is higher by around 3 times compared to that at 25[mTorr].

• Transactions on Electrical and Electronic Materials
• /
• v.11 no.2
• /
• pp.81-84
• /
• 2010

Al-doped ZnO (AZO) films were prepared by an Ar:$H_2$ gas radio frequency (RF) magnetron sputtering system with a AZO ($2\;wt{\cdot}%\;Al_2O_3$) ceramic target at the low temperature of $100^{\circ}C$ and annealed in hydrogen ambient at the temperature of $300^{\circ}C$. To investigate the influence of the $H_2$ flow ratio on the properties of the AZO films, the $H_2$ flow ratio was changed from 0.5% to 2%. As a result, the AZO films, deposited with a 1% $H_2$ addition, showed a resistivity of $11.7\;{\times}\;10^{-4}\;{\Omega}{\cdot}cm$. When the AZO films were annealed at $300^{\circ}C$ for 1 hour in a hydrogen atmosphere, the resistivity decreased from $11.7\;{\times}\;10^{-4}\;{\Omega}{\cdot}cm$ to $5.63\;{\times}\;10^{-4}\;{\Omega}{\cdot}cm$. The lowest resistivity of $5.63\;{\times}\;10^{-4}{\Omega}{\cdot}cm$ was obtained by adding 1% hydrogen gas to the deposition and annealing process. The X-ray diffraction patterns of all the films showed a preferable growth orientation in the (002) plane. The spectrophotometer measurements showed that the transmittance of 85% was obtained by the film deposited with the $H_2$ flow ratio of 1% at 940 nm for GaAs/GaAlAs LEDs.

• Proceedings of the Korean Magnestics Society Conference
• /
• 2005.06a
• /
• pp.74-75
• /
• 2005

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2008.06a
• /
• pp.27-27
• /
• 2008

The different concentration Indium doped ZnO:Al films were grown on glass substrates (Corning 1737) at $200^{\circ}C$ by pulsed laser deposition. The indium doping in AZO films shows the critical effect on the crystallinity, resistivity, and optical properties of the films. The AZO films doped with 0.3 atom % indium content exhibit the highest crystallinity, the lowest resistivity of $4.5\times10^{-4}\Omega$-cm, and the maximum transmittance of 93%. The resistivity of the indium doped-AZO films is strongly related with the crystallinity of the films. The carrier concentration in the indium doped-AZO films linearly increases with increasing indium concentration. The mobility of the AZO films with increasing indium concentration was reduced with an increase in carrier concentration and the decrease in mobility was attributed to the ionized impurity scattering mechanism. In an optical transmittance, the shift of the optical absorption edge to shorter wavelength strongly depends on the electronic carrier concentration in the films.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.61 no.4
• /
• pp.590-594
• /
• 2012

ZnO nanowires were fabricated by hydrothermal synthesis technique for field emission device application. Al-doped zinc oxide (AZO) thin films were prepared as seed layer of catalyst for the ZnO nanowire synthesis, for which conductivity of the seed layer was tried to be improved for enhancing the field emission property of the ZnO nanowire. The AZO seed layer revealed specific resistivity of $ 7.466{\times}10^{-4}[{\Omega}{\cdot}cm]$ and carrier mobility of 18.6[$cm^2$/Vs]. Additionally, upper tip of the prepared ZnO nanowires was treated by hydrochloric acid (HCl) to form a nanocone shape of ZnO nanowire, which was aimed for enhanced focusing of electric field on that and resultingly to improve field emission property of the ZnO nanowires. The ZnO nanowire with nanocone shape revealed decreased threshold electric field and increased current density than those of the simple ZnO nanowires.

• Korean Journal of Materials Research
• /
• v.27 no.3
• /
• pp.161-165
• /
• 2017

In this paper, synthesis of terephthalate intercalated Zn-Al: Layered double hydroxides (LDHs) was studied. We designed freestanding Zn-Al: carbonate LDH nanosheets for a facile exchange technique. The as-prepared Zn-Al carbonate LDHs were converted to terephthalate intercalated Zn-Al:LDHs by ion exchange method. Initially, Al-doped ZnO (AZO) thin films were deposited on p-Si (001) by facing target sputtering. For synthesis of free standing carbonate Zn-Al:LDH, we dipped the AZO thin film in naturally carbonated water for 3 hours. Further, Zn-Al: carbonate LDH nanosheets were immersed in terepthalic acid (TA) solution. The ion exchange phenomena in the terephthalate assisted Zn-Al:LDH were confirmed using FT-IR analysis. The crystal structure of terephthalate intercalated Zn-Al:LDH was investigated by XRD pattern analysis with different mole concentrations of TA solution and reaction times. The optimal conditions for intercalation of terephthalate from carbonated Zn-Al LDH were established using 0.3 M aqueous solution of TA for 24 hours.