• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2001.06a
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• pp.73-73
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• 2001

Boron-containing materials have several excellent properties, such as superlnardness, insulation and non-Rinear optical property. Recently, oxynitride compounds, such as Si(ON), Ti(ON), became the promising materials applied in diffusion barrier layer and solar cell. With the expectation of obtaining the hybrid property, we have firstly grown the BON thin film by radio frequency (R.F.) plasma enhanced metalorganic chemical vapm deposition (PEMOCVD) with 100 kHz frequency and trimethyl borate precursor. The plasma source gases used in this study were Ar and $H_2$, and two kinds of nhmgen source gases, $N_2$ and <$NH_3$, were also employed. The as-grown films were characterized by XPS, IR, SEM and Knoop microlhardness tester. The relationship between the films hardness and the growth rate indicated that the hardness of the film was dependent on several factors such as nitrogen source gas, substrate temperature and film thickness due to the variation of the composition and the structure of the film. Both nitrogen and carbon content could raise the film hardness, on which nitrogen content did stronger effect than carbon. The smooth morphology and continuous structure was benefit of obtaining high hardness. The maximum hardness of BON film was about 10 GPa.

• Korean Journal of Materials Research
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• v.8 no.7
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• pp.621-627
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• 1998

The formation of Co-silicide between Co/Zr bilayer on the amorphous and crystalline Si substrates has been investigated. The films of Zr(50$\AA$) and Co(l50$\AA$) were deposited with e-beam evaporation system and were heattreated with the rapid thermal annealing system at the temperatures between 50$0^{\circ}C$ and 80$0^{\circ}C$ with 10$0^{\circ}C$ increments for 30 seconds. The phase identification of Co-silicide was carried out by XRD and the chemical analysis was examined by AES and RBS. The interface morphologies of Co/Zr bilayer films were investigated by cross sectional TEM and HRTEM. $CoSi_2$ was formed epitaxially on the crystalline Si substrate above $700^{\circ}C$ while polycrystalline $CoSi_2$ was grown on the amorphous Si substrate. The formation temperature of Co-silicide on the amorphous Si substrate was about 100 C lower than that on the crystalline Si. The COzSi phase was not identified on the both Si substrates. The formation temperature of first phase of Co-silicide on ColZr bilayer was higher than that on Co mono layer. CoSizlayer formed on the amorphous Si substrate exhibits better uniformity compared to the CoSiz formed on the crystalline substrate. The sheet resistance of CoSiz layer on crystalline Si was lower than that on the amorphous Si at high temperatures.tures.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.43 no.2 s.344
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• pp.8-12
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• 2006

We have fabricated ZnO thin film on $Pt/TiO-2/SiO_2/Si$ substrate by the sol-gel method and have investigated the effect of annealing temperature on the structural morphology and optical properties of ZnO thin films. The ZnO thin film annealed at $600^{\circ}C$ exhibits the highest c-axis orientation and its FWHM of X-ray peak is $0.4360^{\circ}C$. In the results of surface morphology investigation of ZnO thin film by using Am it is observed that ZnO thin film annealed at $600^{\circ}C$ exhibits the largest UV (ultraviolet) exciton emission at around 378nm and the smallest visible emission at around 510nm among these of ZnO thin films annealed at various temperatures. It is deduced that the ZnO thim film annealed at $600^{\circ}C$ is formed most stoichiometrically since the visible emission at around 510nm comes from oxygen vacancy or impurities.

• Journal of Sensor Science and Technology
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• v.8 no.1
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• pp.10-15
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• 1999

White emission thin film electroluminescent device was fabricated using ZnS for phosphor layer and BST ferroelectric thin film for insulating layer. For fabrication conditions of BST thin film, stoichiometry of target was $Ba_{0.5}Sr_{0.5}TiO_3$, substrate temperature was $400^{\circ}C$, working pressure was 30 mTorr, and A:$O_2$ ratio was 9:1. At this time, dielectric constant was 209 at 1kHz frequency. For phosphor layer ZnS:Mn, ZnS:Tb, and ZnS:Ag were used. Mixing rates of activators were respectively 0.8, 0.8, and 1 wt%. Total thickness of phosphor tapers was 500 nm, thickness of lower insulating layer was 200 nm, and thickness of upper insulating layer was 400 nm. In this conditions, luminescence threshold voltage of thin film electroluminescent device was $95\;V_{rms}$, maximum brightness was $3,000\;cd/m^2$ at $150\;V_{rms}$. Luminescence spectrum peak was observed at region of blue(450 nm), green(550 nm), and red(600 nm).

• Korean Journal of Materials Research
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• v.9 no.1
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• pp.86-91
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• 1999

We have fabricated high-$\textrm{T}_c$ superconducting $\textrm{YBa}_{2}\textrm{Cu}_{3}\textrm{O}_{7-x}$(YBCO) grain boundary junctions at a step-edge on (001) $\textrm{SrTiO}_3$(STO) substrates. A diamond-like carbon (DLC) film grown by plasma enhanced chemical vapor deposition were used as an ion milling mask to make steps on the STO (100) single crystal and was removed by an oxygen reactive ion etch process. The c-axis oriented YBCO and TO thin films were deposited epitaxially on the STO substrate with a step-edge by pulsed laser deposition. The grain boundary junctions were formed at the top and the bottom of the step. The junctions worked at temperatures above 77 K, and had I\ulcornerR\ulcorner products of 7.5mV at 16K and 0.3 mV at 77K, respectively. The I-V characteristics of these junctions showed the shape of the two noisy resistively shunted junction model.

• Journal of the Korean Vacuum Society
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• v.16 no.2
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• pp.128-133
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• 2007

In this study, we observed the shapes of CNTs formed with the thinckness of catalyst. Catalyst layer was grown by magnetron sputtering method and the thickness of Ni catalyst is the range from 20 to 80 nm. Also, the synthesis of CNT with Ni catalyst thickness was grown by hot-filament PECVD method. And, we investigated the composition of CNTs by using EDS measurement, also observed the shapes of CNTs by using HRTEM and FESEM measurements. In the result, through the TEM analysis, we observed the empty inside of CNTs and the multiwall CNTs, also confirmed the tip of CNT containing Ni. The composition of CNTs are consisted of an element of C, Ti, and Ni. As you shown the growth shapes of CNTs, the pretreatment of the catalyst before te growth of CNTs changed the particle size of the catalysts and grown the CNTs of the different shapes. Consequently, the best vertically alined and well-arranged CNTs exhibited from the substrate deposited at the catalyst thickness of 40 nm.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.410-410
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• 2013

Next-generation nonvolatile memory (NVM) has attracted increasing attention about emerging NVMs such as ferroelectric random access memory, phase-change random access memory, magnetic random access memory and resistance random access memory (RRAM). Previous studies have demonstrated that RRAM is promising because of its excellent properties, including simple structure, high speed and high density integration. Many research groups have reported a lot of metal oxides as resistive materials like TiO2, NiO, SrTiO3 and ZnO [1]. Among them, the ZnO-based film is one of the most promising materials for RRAM because of its good switching characteristics, reliability and high transparency [2]. However, in many studies about ZnO-based RRAMs, there was a problem to get lower current level for reducing the operating power dissipation and improving the device reliability such an endurance and an retention time of memory devices. Thus in this paper, we investigated that highly reproducible bipolar resistive switching characteristics of W doped ZnO RRAM device and it showed low resistive switching current level and large ON/OFF ratio. This may be caused by the interdiffusion of the W atoms in the ZnO film, whch serves as dopants, and leakage current would rise resulting in the lowering of current level [3]. In this work, a ZnO film and W doped ZnO film were fabricated on a Si substrate using RF magnetron sputtering from ZnO and W targets at room temperature with Ar gas ambient, and compared their current levels. Compared with the conventional ZnO-based RRAM, the W doped ZnO ReRAM device shows the reduction of reset current from ~$10^{-6}$ A to ~$10^{-9}$ A and large ON/OFF ratio of ~$10^3$ along with self-rectifying characteristic as shown in Fig. 1. In addition, we observed good endurance of $10^3$ times and retention time of $10^4$ s in the W doped ZnO ReRAM device. With this advantageous characteristics, W doped ZnO thin film device is a promising candidates for CMOS compatible and high-density RRAM devices.

• Korean Journal of Materials Research
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• v.11 no.8
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• pp.671-678
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• 2001

All solid-state thin film micro supercapacitor, which consists of $RuO_2$/LiPON/$RuO_2$ multi layer structure, was fabricated on Pt/Ti/Si substrate using a $RuO_2$ electrode. Bottom $RuO_2$ electrode was grown by dc reactive sputtering system with increasing $O_2/[Ar+O_2]$ ratio at room temperature, and a LiPON electrolyte film was subsequently deposited on the bottom $RuO_2$ electrode at pure nitrogen ambient by rf reactive sputtering system. Room temperature charge-discharge measurements based on a symmetric $RuO_2$/LiPON/$RuO_2$ structure clearly demonstrates the cyclibility dependence on the microstructure of the $RuO_2$ electrode. Using both glancing angle x-ray diffraction (GXRD) and transmission electron microscopy (TEM) analysis, it was found that the microstructure of the $RuO_2$ electrode was dependent on the oxygen flow ratio. In addition, x- ray photoelectron spectroscopy(XPS) examination shows that the Ru-O binding energy is affected by increasing oxygen flow ratio. Furthermore, TEM and AES depth profile analysis after cycling demonstrates that the interface layer formed by interfacial reaction between LiPON and $RuO_2$ act as a main factor in the degradation of the cyclibility of the thin film micro-supercapacitor.

• Journal of the Microelectronics and Packaging Society
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• v.14 no.2 s.43
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• pp.59-63
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• 2007

This paper presented a low-cost thick film gas sensor module, which was based on simple PCB (Printed Circuit Board) process. The proposed sensor module included a $NO_2/H_2$ gas sensor, a relative humidity sensor, and a heating element. The $NO_2/H_2$ gas and relative humidity sensors were realized by screen-printing $SnO_2,\;BaTiO_3$ nano-powders on IDTS (Interdigital Transducer) of a PCB substrate, respectively. At first 1% $H_2$ gas flowed into the sensor chamber. After 4 min, air filled the chamber while $H_2$ gas flow stopped. This experiment was performed repeatedly. The Identical procedure was used for the $NO_2$ detection. The result for sensing $H_2$ gas showed the increase of voltage from 0.8V to 3.5V due to the conductance increase and its reaction response time by hydrogen flow was 65 sec. $NO_2$ sensing results showed 2.7 V voltage drop due to the conductance decrease and its response time was 3 sec through a voltage monitoring.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.36D no.11
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• pp.63-70
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• 1999

A PLT(10) thin film has been deposited on $Pt/TiO_2/SiO_2/Si$ substrate by sol-gel method, and its switching characteristics have been investigated with various top electrode areas, input pulse voltages and loan resistances. As the external input pulse voltage increases from 2V to 5V, the switching time decreases from $0.49{\mu}s$ to $0.12{\mu}s$. The activation energy ($E_a$) obtained from the relations between the switching time and the applied pulse voltage is evaluated as 209kV/cm. The switched charge densities at 5V obtained from the hysteresis loop and the polarization switching are $11.69{\mu}C/cm^2$ and $13.02{\mu}C/cm^2$, respectively, which agree relatively well with each other and show the difference of 10%. When the top electrode area increases from TEX>$3.14{\times}10^{-4}cm^2$ to $5.03{\times}10^{-3}cm^2$ and the load resistance increases from 50${\Omega}$ to 3.3$k{\Omega}$, the switching time increases from $0.12{\mu}s$ to $1.88{\mu}s$ and from $0.12{\mu}s$ to $9.7{\mu}s$, respectively. These switching characteristics indicate that PLT(10) thin film can be well applied in nonvolatile memory devices.