• Proceedings of the Korean Vacuum Society Conference
• /
• 2013.08a
• /
• pp.211.1-211.1
• /
• 2013

We fabricate the conductive zinc oxide(ZnO) thin film using UV-enhanced atomic layer deposition. ZnO is semiconductor with a wide band gap(3.37eV) and transparent in the visible region. ZnO can be deposited with various method, such as metal organic chemical vapour deposition, magnetron sputtering and pulsed laser ablation deposition. In this experiment, ZnO thin films was deposited by atomic layer deposition using diethylzinc (DEZ) and D.I water as precursors with UV irradiation during water dosing. As a function of UV exposure time, the resistivity of ZnO thin films decreased dramatically. We were able to confirm that UV irradiation is one of the effective way to improve conductivity of ZnO thin film. The resistivity was investigated by 4 point probe. Additionally, we confirm the thin film composition is ZnO by X-ray photoelectron spectroscopy. We anticipate that this UV-enhanced ZnO thin film can be applied to electronics or photonic devices as transparent electrode.

• Korean Journal of Materials Research
• /
• v.28 no.1
• /
• pp.32-37
• /
• 2018

We report on the efficient detection of NO gas by an all-oxide semiconductor p-n heterojunction diode structure comprised of n-type zinc oxide (ZnO) nanorods embedded in p-type copper oxide (CuO) thin film. The CuO thin film/ZnO nanorod heterostructure was fabricated by directly sputtering CuO thin film onto a vertically aligned ZnO nanorod array synthesized via a hydrothemal method. The transport behavior and NO gas sensing properties of the fabricated CuO thin film/ZnO nanorod heterostructure were charcterized and revealed that the oxide semiconductor heterojunction exhibited a definite rectifying diode-like behavior at various temperatures ranging from room temperature to $250^{\circ}C$. The NO gas sensing experiment indicated that the CuO thin film/ZnO nanorod heterostructure had a good sensing performance for the efficient detection of NO gas in the range of 2-14 ppm under the conditions of an applied bias of 2 V and a comparatively low operating temperature of $150^{\circ}C$. The NO gas sensing process in the CuO/ZnO p-n heterostructure is discussed in terms of the electronic band structure.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.30 no.11
• /
• pp.705-709
• /
• 2017

Effective surface area and morphology of a sensitive thin film are important factors for its applications in sensor systems for the analysis of physical properties. In this study, we investigated the morphologies, electrochemical properties, and applicability of zinc oxide multilayer thin films fabricated by electrodeposition and annealing. The microstructure and electrochemical properties of the zinc oxide films were dependent on temperature and applied voltage. The best characteristics were obtained at an applied voltage of -1.4 V and a temperature of $50^{\circ}C$. The morphologies also changed upon annealing. The results suggest that the zinc oxide films fabricated by electrodeposition and annealing can be applied as various sensor materials.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2011.02a
• /
• pp.90-90
• /
• 2011

Transparent conducting oxide (TCO) films have been intensively utilized in the electric applications, such as, displays, lightings and solar cells due to the good electric conductivity with an excellent transmittance of the visible light. We, herein present an excellent Al-doped ZnO film (AZO), which has been fabricated by co-sputtering method. An as-deposited AZO film had an optical transmittance of 84.78% at 550 nm and a resistivity of $7.8{\times}10^{-3}{\Omega}cm$. A rapid annealing process significantly improved the optical transmittance and electrical resistivity of the AZO film to 99.67% and $1{\times}10^{-3}{\Omega}cm$, respectively. The fabricated AZO film was fabricated for a metal-semiconductor-metal (MSM) structure. The AZO film-embedding MSM device was highly responsive to a UV light.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2015.08a
• /
• pp.235.2-235.2
• /
• 2015

The front transparent conductive oxide (TCO) films must exhibit good transparency, low resistivity and excellent light scattering properties for high efficiency amorphous silicon (a-Si) thin film solar cells. The light trapping phenomenon is limited due to non-uniform and low aspect ratio of the textured glass [1]. We present the low cost electrochemically deposited uniform zinc oxide (ZnO) nanorods with various aspect ratios for a-Si thin film solar cells. Since the major drawback of the electrochemically deposited ZnO nanorods was the high sheet resistance and low transmittance that was overcome by depositing the RF magnetron sputtered AZO films as a seed layer with various thicknesses [2]. The length and diameters of the ZnO nanorods was controlled by varying the deposition conditions. The length of ZnO nanorods were varied from 400 nm to $2{\mu}m$ while diameter was kept higher than 200 nm to obtain different aspect ratios. The uniform ZnO nanorods showed higher haze ratio as compared to the commercially available FTO films. We also observed that the scattering in the longer wavelength region was favored for the high aspect ratio of ZnO nanorods and much higher aspect ratios degraded the light scattering phenomenon. Therefore, we proposed our low cost and uniform ZnO nanorods for the high efficiency of thin film solar cells.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2015.08a
• /
• pp.236.1-236.1
• /
• 2015

The surface morphology of front transparent conductive oxide (TCO) films is very important to achieve high current density in amorphous silicon (a-Si) thin film solar cells since it can scatter the light in a better way. In this study, we present the low cost hydrothermal deposited uniform zinc oxide (ZnO) nano-flower structure with various aspect ratios for a-Si thin film solar cells. The ZnO nano-flower structures with various aspect ratios were grown on the RF magnetron sputtered AZO films. The diameters and length of the ZnO nano-flowers was controlled by varying the annealing time. The length of ZnO nano-flowers were varied from 400 nm to $2{\mu}m$ while diameter was kept higher than 200 nm to obtain different aspect ratios. The ZnO nano-flowers with higher surface area as compared to conventional ZnO nano structure are preferred for the better light scattering. The conductivity and crystallinity of ZnO nano-flowers can be enhanced by annealing in hydrogen atmosphere at 350 oC. The vertical aligned ZnO nano-flowers showed higher haze ratio as compared to the commercially available FTO films. We also observed that the scattering in the longer wavelength region was favored for the high aspect ratio of ZnO nano-flowers. Therefore, we proposed low cost and vertically aligned ZnO nano-flowers for the high performance of thin film solar cells.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2009.10a
• /
• pp.1582-1585
• /
• 2009

The effects of bias stress on spin-coated zinc tin oxide (ZTO) transistors are investigated. Applying a positive bias stress results in the displacement of the transfer curves in the positive direction without changing the field effect mobility or the subthreshold behavior. Device instability appears to be a consequence of the charging and discharging of temporal trap states at the interface and in the zinc tin oxide channel region.

• Proceedings of the KIEE Conference
• /
• 1988.11a
• /
• pp.355-358
• /
• 1988

Polycrystalline transparent semiconducting zinc oxide film has been characterized for their electrical properties. The conductivity of the film could be increased by approximately five times of magnitude by annealing it in hydrogen at 400 C. The electrical properties measured on the temperature range of RT to 120 K give support well to the model which depicts the importance of the grain boundary effects on the electrical conduction of zinc oxide film.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2010.08a
• /
• pp.251-251
• /
• 2010

Organic-inorganic hybrid materials have attracted because of its combined properties, such as flexibility and high electrical performance. In addition, the hybrid materials are expected to have synergic effect which are not shown in just one component. Here, we fabricated organic-inorganic hybrid thin film. Organic-inorganic hybrid thin film have been deposited from diethyl zinc and 1, 2, 4-trihydroxybenzene (THB) by molecular layer deposition (MLD). UV-VIS, Using Infrared spectrum and X-ray photoelectron spectroscopy confirm that Zinc and THB hybrid film (ZnTHB) consist of Zn-O and THB - oxide units and the micro structure and composition of hybrid film. hat the sequential surface reactions of diethyl zinc and ethylene glycol are sufficiently self-limiting and saturating to enable well-controlled MLD growth. Transmission electron microscopy image shows lamination growth of ZnTHB film according to cycle.

• Current Applied Physics
• /
• v.18 no.11
• /
• pp.1300-1305
• /
• 2018

The tunable electronic performance of the solution-processed semiconductor metal oxide is of great significance for the printing electronics. In current work, transparent thin-film transistors (TFTs) with indium-zinc oxide (IZO) were fabricated as active layer by a simple eco-friendly aqueous route. The aqueous precursor solution is composed of water without any other organic additives and the IZO films are amorphous revealed by the X-ray diffraction (XRD). With systematic studies of atomic force microscopy (AFM), X-ray photoemission spectroscopy (XPS) and the semiconductor property characterizations, it was revealed that the electrical performance of the IZO TFTs is dependent on the concentration of precursor solution. As well, the optimum preparation process was obtained. The concentrations induced the regulation of the electronic performance was clearly demonstrated with a proposed mechanism. The results are expected to be beneficial for development of solution-processed metal oxide TFTs.