• Transactions on Electrical and Electronic Materials
• /
• v.13 no.4
• /
• pp.185-187
• /
• 2012

Ga doped ZnO (GZO)/copper (Cu) bi-layered film was deposited on glass substrate by RF and DC magnetron sputtering and then the effect of the Cu bottom layer on the optical, electrical and structural properties of GZO films were considered. As-deposited 100 nm thick GZO films had an optical transmittance of 82% in the visible wavelength region and a sheet resistance of 4139 ${\Omega}/{\Box}$, while the GZO/Cu film had optical and electrical properties that were influenced by the Cu bottom layer. GZO films with 5 nm thick Cu film show the lower sheet resistance of 268 ${\Omega}/{\Box}$ and an optical transmittance of 65% due to increased optical absorption by the Cu metallic bottom layer. Based on the figure of merit, it can be concluded that the thin Cu bottom layer effectively increases the performance of GZO films as a transparent and conducting electrode without intentional substrate heating or a post deposition annealing process.

• Proceedings of the KIEE Conference
• /
• 2009.07a
• /
• pp.1277_1278
• /
• 2009

Amorphous oxide semiconductor $InGaZnO_4$(IGZO) is a very promising candidate of channel layer in transparent thin film trasisitor(TTFT) because of its high mobility and high transparency in visible light region. Amorphous IGZO films were deposited at room temperature on a fused silica substrate using pulsed laser deposition method. In-situ post annealing was carried out at 150-450C right after film deposition. The $O_2$ partial pressures during the deposition and the post annealing was fixed to 10mTorr. The electron transport properties of the amorphous IGZO films were improved by thermal annealing. The temperature range in which the improvement of the electrical properties, was 150C~300C.

• Journal of the Korean Vacuum Society
• /
• v.21 no.1
• /
• pp.17-21
• /
• 2012

Ga-doped ZnO (GZO) thin films for application as transparent conducting oxide film were deposited on the glass substrate by using rf-magnetron sputtering system. The effects of working pressure on electrical and optical characteristics of GZO films were investigated. Regardless of the working pressure, all films were oriented along with the c-axis, perpendicular to the substrate. The electrical resistivity was about $8.68{\times}10^{-3}{\Omega}{\cdot}cm\sim2.18{\times}10^{-3}{\Omega}{\cdot}cm$ and the average transmittance of all films including substrates was over 90% in the visible range. The good transparents and conducting properties were obtained due to controle the working pressure. The obtained results have acceptable for application as transparent conductive electrodes in LCDs and solar cells.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2010.06a
• /
• pp.296-296
• /
• 2010

In this work, we report the effect of substrate on the growth of Ga-doped ZnO (GZO) thin films. GZO thin films were deposited on various substrates by using pulsed laser deposition (PLD). The structural properties, surface morphologies, and electrical properties were investigated. From the results of HRXRD, c-plane (0002) oriented growth of GZO films was confirmed on $Al_2O_3$ (0001). On the other hand, the GZO films on LAO (100) substrates were grown along the a-axis. The obvious differences on the electrical properties of each film were also obtained.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.29 no.1
• /
• pp.1-5
• /
• 2016

The ultimate aims of display market is transparent or flexible. Researches have been carried out for various applications. It has been possible to reduced the process steps and get good electrical properties for semiconductors with large optical bandgaps. Oxide semiconductors have been established as one of the leading and promising technology for next generation display panels. In this paper, alternative treatment processes have been tried for oxide semiconductors of thin film transistors to increase the electrical properties of the thin film transistors and to investigate the mechanisms. There exist a various oxide semiconductors. Here, we focused on InGaZnO, ZnO and InSnZnO which are commercialized or researched actively.

• Journal of the Korean Vacuum Society
• /
• v.16 no.5
• /
• pp.359-365
• /
• 2007

In this paper we present a bottom-gate type of zinc oxide (ZnO) and Gallium (Ga) doped zinc oxide (GZO) based thin film transistors (TFTs) through applying a radio frequency (RF) magnetron sputtering method at room temperature. The gate leakage current can be reduced up to several ph by applying $SiO_2$ thermally grown instead of using new gate oxide materials. The root mean square (RMS) values of the ZnO and GZO film surface were measured as 1.07 nm and 1.65 nm, respectively. Also, the transmittances of the ZnO and GZO film were more than 80% and 75%, respectively, and they were changed as their film thickness. The ZnO and GZO film had a wurtzite structure that was arranged well as a (002) orientation. The ZnO TFT had a threshold voltage of 2.5 V, a field effect mobility of $0.027\;cm^2/(V{\cdot}s)$, a on/off ratio of $10^4$, a gate voltage swing of 17 V/decade and it operated in a enhancement mode. In case of the GZO TFT, it operated in a depletion mode with a threshold voltage of -3.4 V, a field effect mobility of $0.023\;cm^2/(V{\cdot}s)$, a on/off ratio of $2{\times}10^4$ and a gate voltage swing of 3.3 V/decade. We successfully demonstrated that the TFTs with the enhancement and depletion mode type can be fabricated by using pure ZnO and 1wt% Ga-doped ZnO.

• Proceedings of the Optical Society of Korea Conference
• /
• 2002.11a
• /
• pp.18-19
• /
• 2002

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2009.06a
• /
• pp.44-44
• /
• 2009

Recently, transparent ZnO-based TFTs have attracted much attention for flexible displays because they can be fabricated on plastic substrates at low temperature. We report the fabrication and characteristics of ZnO channel layers(ZnO TFTs) having different channel thicknesses. The ZnO film were deposited as active channel layers on $Si_3N_4/Ti/SiO_2p$-Si substrates by rf magnetron sputtering at $100\;^{\circ}C$ without additional annealing. Also the Zno thin films deposited at oxygen partial pressures of 40%. ZnO TFTs using a bottom-gate configuration were investigated. The $Si_3N_4$ film were deposited as gate insulator by PE-CVD at $15\;^{\circ}C$. All Processes were processed below $150^{\circ}C$ which is optimal temperature for flexible display and were used dry etching method.

• Korean Journal of Metals and Materials
• /
• v.47 no.1
• /
• pp.38-43
• /
• 2009

To investigate the effect of RF power on the structural, optical and electrical properties of amorphous InGaZnO (a-IGZO), its thin films and TFTs were prepared by RF magnetron sputtering method with different RF power conditions of 40, 80 and 120 W at room temperature. In this study, as RF power during the deposition process increases, the RMS roughness of a-IGZO films increased from 0.26 nm to 1.09 nm, while the optical band-gap decreased from 3.28 eV to 3.04 eV. In the case of the electrical characteristics of a-IGZO TFTs, the saturation mobility increased from $7.3cm^2/Vs$ to $17.0cm^2/Vs$, but the threshold voltage decreased from 5.9 V to 3.9 V with increasing RF power. It is regarded that the increment of RF power increases the carrier concentration of the a-IGZO semiconductor layer due to the higher generation of oxygen vacancies.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2005.11a
• /
• pp.95-96
• /
• 2005

The general method and mechanism for the polarity control of heteroepitaxial wurtzite films, such as ZnO and GaN, by interface engineering via plasma-assisted molecular beam epitaxy are addressed. We proposed the principle and method controlling the crystal polarity of ZnO on GaN and GaN on ZnO. The crystal polarity of the lower film was maintained by forming a heterointerfce without any interface layer between the upper and the lower layers. However the crystal polarity could be changed by forming the heterointerface with the interface layer having an inversion center. The principle and method suggested here give us a promising tool to fabricate polarity inverted heterostructures, which applicable to invent novel heterostructures and devices.