• Korean Journal of Materials Research
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• v.15 no.4
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• pp.275-280
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• 2005

The growth of hafnium oxide thin films by atomic layer deposition was investigated in the temperature range of $175-350^{\circ}C$ using $Hf[N(CH_3)_2]_4\;and\;O_2$ as precursors. A self-limiting growth of $0.6\AA/cycle$ was achieved at the substrate temperature of $240-280^{\circ}C$. The films were amorphous and very smooth (0.76-0.80 nm) as examined by X-ray diffractometer and atomic force microscopy, respectively. X-ray photoelectron spectroscopy analysis showed that the films grown at $300^{\circ}C$ was almost stoichiometric. Electrical measurements performed on $MoW/HfO_2$(20 nm)/Si MOS structures exhibited high dielectric constant$(\~17)$ and a remarkably low leakage current density of at an applied field of $1.5-6.2\times10^{-7}A/cm^2$ MV/cm, probably due to the stoichiometry of the films.

• Journal of the Korean institute of surface engineering
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• v.48 no.2
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• pp.50-55
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• 2015

$Al_2O_3$ thin films were deposited on the moth eye anti-reflective nanostructured polycarbonate films by atomic layer deposition (ALD) techniques. Without ALD-$Al_2O_3$ thin films, moth eye anti-reflective nanostructured films had a high optical transmittance of 95.47% at a wavelength of 550 nm and a very poor hardness of 0.1381 GPa. With increasing the thickness of $Al_2O_3$ thin films from 5 to 25 nm, the transmittance of moth eye anti-reflective nanostructured films was gradually decreased from 94.94 to 93.12%. On the other hand, the hardness of the films was greatly increased from 0.3498 to 0.7806 GPa with increasing the thickness of $Al_2O_3$ thin films. This result shows that ALD thin films can be applied to improve mechanical properties with an adequate optical transmittance of the conventional moth eye anti-reflection nanostructure films.

• Journal of the Korean institute of surface engineering
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• v.48 no.2
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• pp.38-42
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• 2015

Atomic layer deposition (ALD) is essential for the fabrication of nanoscale electronic devices because it has excellent conformality, atomic scale thickness control, and large area uniformity. Metal thin films are one of the important material components for electronic devices as a conductor. As the size of electronic devices shrinks, the thickness of metal thin films is decreased down to few nanometers, and the metal films become non-continuous due to inherent island growth of metal below a critical thickness. So, fabrication of continuous metal thin films by ALD is fundamentally and practically important. Since ALD films are grown through self-saturated reactions between precursors on surface, initial growth characteristics significantly depend on the surface properties and the selection of precursors. In this work, we investigated ALD Pt on $TiO_2$ substrate by using trimethyl-methyl-cyclopentadienyl-Platinum ($MeCpPtMe_3$) precursor and $O_3$ reactant. By using $O_3$ instead of $O_2$, initial nucleation rate of ALD Pt was increased on $TiO_2$ surface, resulting in formation of continuous thin Pt films. Morphologies of ALD Pt on $TiO_2$ were characterized by using Scanning Electron Microscope (SEM) and Energy-Dispersive X-ray Spectroscopy (EDS). Crystallinity of ALD Pt on $TiO_2$ correlated with its growth characteristics was analyzed by X-Ray Diffraction (XRD).

• Journal of the Microelectronics and Packaging Society
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• v.27 no.1
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• pp.31-35
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• 2020

This study demonstrates metal-oxide based memtransistor device and the gate tunable memristive characteristic using atomic layer deposition (ALD) and ZnO n-type oxide semiconductor. We fabricated a memtransistor device having channel width 70 ㎛, channel length 5 ㎛, back gate, using 40 nm thick ZnO thin film, and measured gate-tunable memristive characteristics at each gate voltage (50V, 30V, 10V, 0V, -10V, -30V, -50V) under humidity of 40%, 50%, 60%, and 70% respectively, in order to investigate the relation between a memristive characteristic and hydrogen doping effect on the ZnO memtransistor device. The electron mobility and gate controllability of memtransistor device decreased with an increase of humidity due to increased electron carrier concentration by hydrogen doping effect. The gate-tunable memristive characteristic was observed under humidity of 60% 70%. Resistive switching ratio increased with an increase of humidity while it loses gate controllability. Consequently, we could obtain both gate controllability and the large resistive switching ratio under humidity of 60%.

• Korean Journal of Materials Research
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• v.28 no.4
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• pp.241-246
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• 2018

$TaN_x$ film is grown by plasma enhanced atomic layer deposition (PEALD) using t-butylimido tris(dimethylamido) tantalum as a metalorganic source with various reactive gas species, such as $N_2+H_2$ mixed gas, $NH_3$, and $H_2$. Although the pulse sequence and duration are the same, aspects of the film growth rate, microstructure, crystallinity, and electrical resistivity are quite different according to the reactive gas. Crystallized and relatively conductive film with a higher growth rate is acquired using $NH_3$ as a reactive gas while amorphous and resistive film with a lower growth rate is achieved using $N_2+H_2$ mixed gas. To examine the relationship between the chemical properties and resistivity of the film, X-ray photoelectron spectroscopy (XPS) is conducted on the ALD-grown $TaN_x$ film with $N_2+H_2$ mixed gas, $NH_3$, and $H_2$. For a comparison, reactive sputter-grown $TaN_x$ film with $N_2$ is also studied. The results reveal that ALD-grown $TaN_x$ films with $NH_3$ and $H_2$ include a metallic Ta-N bond, which results in the film's higher conductivity. Meanwhile, ALD-grown $TaN_x$ film with a $N_2+H_2$ mixed gas or sputtergrown $TaN_x$ film with $N_2$ gas mainly contains a semiconducting $Ta_3N_5$ bond. Such a different portion of Ta-N and $Ta_3N_5$ bond determins the resistivity of the film. Reaction mechanisms are considered by means of the chemistry of the Ta precursor and reactive gas species.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.40-40
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• 2010

Structural, electrical, and optical properties of atomic layer-controlled AI-doped ZnO (ZnO:Al) films grown on glass by atomic layer deposition (ALD) were characterized with various $Al_2O_3$ film contents for use as transparent electrodes. Unlike films made using sputtering methods, the diffraction peak position of the films grown by ALD based on alternate self-limiting surface chemical reactions moved progressively to a wider angle (red shift) with increasing $Al_2O_3$ film content, which seems to be evidence of Zn substitution in the film by layer-by-layer growth. By adjusting the $Al_2O_3$ film content, the electrical resistivity of ZnO:Al film with the $Al_2O_3$ film content of 2.96% reached the lowest electrical resistivity of $9.80{\times}10^{-4}\Omega{\cdot}cm$, in which the carrier mobility, carrier concentration, and optical transmittance were $11.20\;cm^2V^{-1}s^{-1}$, $5.69{\times}10^{20}\;cm^{-3}$, and 94.23%, respectively. Moreover, the estimated figure of merit value for the transparent conductive oxide applications from our best sample was $7.7\;m{\Omega}^{-1}$.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.4
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• pp.350-354
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• 2009

$Al_{2}O_{3}$ thin films were deposited on GaN(0001) by using a Remote Plasma Atomic Layer Deposition(RPALD) technique with a trimethylaluminum(TMA) precursor and oxygen radicals in the temperature range of $25{\sim}500^{\circ}C$. The growth rate per cycle was varied with the substrate temperature from $1.8{\AA}$/cycle at $25^{\circ}C$ to $0.8{\AA}$/cycle at $500^{\circ}C$. The chemical structure of the $Al_{2}O_{3}$ thin films was studied using X-ray photoelectron spectroscopy(XPS). The electrical properties of $Al_{2}O_{3}$/GaN Metal-Insulator-Semiconductor (MIS) capacitor grown at a $300^{\circ}C$ process temperature were excellent, a low electrical leakage current density(${\sim}10^{-10}A/cm^2$ at 1 MV) at room temperature and a high dielectric constant of about 7.2 with a thinner oxide thickness of 12 nm. The interface trap density($D_{it}$) was estimated using a high-frequency C-V method measured at $300^{\circ}C$. These results show that the RPALD technique is an excellent choice for depositing high-quality $Al_{2}O_{3}$ as a Sate dielectric in GaN-based devices.

• Journal of the Korean Vacuum Society
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• v.18 no.5
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• pp.384-389
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• 2009

ZnO, a wurtzite lattice structure, has attracted much attention as a promising material for light-emitting diodes (LEDs) due to highly efficient UV emission resulting from its large band gap of 3.37 eV, large exciton binding energy of 60 meV, and low power threshold for optical pumping at room temperature. For the realization of LEDs, both n-type ZnO and p-type ZnO are required. Now, n-type ZnO for practical applications is available; however, p-type ZnO still has many drawbacks. In this study, ZnO films were grown on glass substrates by using atomic layer deposition (ALD) and the ZnO films were irradiated by nitrogen ion beams (20 keV, $10^{13}{\sim}10^{15}ions/cm^2$). The effects of nitrogen-beam irradiation on the ZnO structure as well as the electrical property were investigated by using fieldemission scanning electron microscopy (FESEM) and Hall-effect measurement.

• Proceedings of the Korean Society Of Semiconductor Equipment Technology
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• 2005.05a
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• pp.139-145
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• 2005

In the study, in order to deposit TaN thin film using diffusion barrier and bottom electrode we made the Plasma Assisted ALD equipment and confirmed the electrical characteristic of TaN thin films deposited PAALD method, PAALD equipment depositing TaN thin film using PEMAT(pentakis(ethylmethlyamlno) tantalum) Precursor and $NH_3$ reaction gas is aware that TaN thin film deposited of high density and amorphous phase with XRD measurement The degree of diffusion and react ion taking place in Cu/TaN(deposited using 150 W PAALD)/$SiO_2$/Si systems with increasing annealing temperature was estimated from MOS capacitor property and the $SiO_2(600\;\AA)$/Si system surface analysis by C-V measurement and secondary ion material spectrometer(SIMS) after Cu/TaN/$SiO_2(400\;\AA)$ system etching. TaN thin film deposited PAALD method diffusion barrier have a good diffusion barrier property up to $500^{\circ}C$.

• Journal of the Korean Vacuum Society
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• v.19 no.2
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• pp.105-113
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• 2010

One-dimensional nanostructures have been researched widely because of its unique physical properties such as optical, electrical, mechanical, and chemical properties in comparison with bulk structures. Especially nanotubular structures are able to provide larger surface area, capability to load purposeful materials, and unique mechanical modulus. We reviewed the oxide nanotube technology with focusing on the method of template-directed fabrication. We can easily control of physical dimensions of nanotubes by control of nanotemplate and fabrication condition. and template-directed fabrication is ideal tool to fabricate the amount of monodisperse nanotubes. They have potentials for application in solar cell, drug-delivery, Li-ion batteries and photocatalyst. We discussed these potential applications and research trends.