• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.663-664
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• 2006

Sintered Ti(C,N)-based cermets were treated with hot isostatic pressing (HIP) at different nitrogen pressures. The tribological properties of the treated cermets have been evaluated. The results show that a hard near-surface area rich in TiN formed after HIP treatment. The cermets treated at higher pressure had a relatively lower friction coefficient and specific wear rate. In all cases the microhardness of treated cermets is higher than that without HIP natridation. The wear mechanisms of cermets were hard particle flaking-off and ploughing. It was also found that the HIP natridation is well-suited for improving the tribological properties of cermets.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07a
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• pp.17-19
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• 2004

The electrical properties of gate oxides grown in two different processes, which are in 10% nitrous oxide($N_2O$) and in dry oxygen, have been experimentally investigated and compared. It has been observed that the $SiC-SiO_2$ interface-trap density(Dit) measured in nitrided gate oxide has been tremendously reduced, compared to the density obtained from gate oxide grown in dry oxygen. The beneficial effects of nitridation on gate oxides also have been demonstrated in the values of total near interface-trap density and of forward-bias breakdown field. The reasons of these improvements have been explained.

• Journal of Magnetics
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• v.9 no.1
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• pp.17-22
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• 2004

We studied the magnetotransport properties of tunnel junctions with AlO and AlN barriers fabricated using microwave-excited plasma. The plasma nitridation process provided wider controllability than the plasma oxidization for the formation of MTJs with ultra-thin insulating layer, because of the slow nitriding rate of metal Al layers, comparing with the oxidizing rate of them. High tunnel magnetoresistance (TMR) ratios of 49 and 44% with respective resistance-area product $(R{\times}A) of 3 {\times} 10^4 and 6 {\times} 10^3 {\Omega}{\mu}m^2$ were obtained in the Co-Fe/Al-N/Co-Fe MTJs. We conclude that AlN is a hopeful barrier material to realize MTJs with high TMR ratio and low $R{\times}A$ for high performance MRAM cells. In addition, in order to clarify the annealing temperature dependence of TMR, the local transport properties were measured for Ta $50{\AA} /Cu 200 {\AA}/Ta 50 {\AA}/Ni_{76}Fe_{24} 20 {\AA}/Cu 50 {\AA}/Mn_{75}Ir_{25} 100 {\AA}/Co_{71}Fe_{29} 40 {\AA}/Al-O$ junction with $d_{Al}= 8 {\AA} and P_{O2}{\times}t_{0X}/ = 8.4 {\times} 10^4$ at various temperatures. The current histogram statistically calculated from the electrical current image was well in accord with the fitting result considering the Gaussian distribution and Fowler-Nordheim equation. After annealing at $340^{\circ}C$, where the TMR ratio of the corresponding MTJ had the maximum value of 44%, the average barrier height increased to 1.12 eV and its standard deviation decreased to 0.1 eV. The increase of TMR ratio after annealing could be well explained by the enhancement of the average barrier height and the reduction of its fluctuation.

• Korean Journal of Materials Research
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• v.7 no.11
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• pp.986-990
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• 1997

LED와 LD의 수명과 효율은 결정에 존재하는 결함의 밀도에 반비례하며, 이러한 결함의 밀도는 적당한 기판을 사용하거나, 기판의 표면을 적절하게 제어함으로써 줄일 수 있다. GaN성장시 원자 단위의 매끄러운 표면은 완충충 성장이나 질화처리를 함으로써 얻어질 수 있다. 이렇게 얻어진 원자 단위의 매끄러운 표면에 의해 기판과 박막상이의 계면 자유에너지가 감소하기 때문에 2D성장이 촉진된다. 사파이어(AI$_{2}$O$_{3}$(0001))기판을 사용한 GaN 왕충충성장과 진화처리에 대한 최적조건은 AFM(Atomic Force Microscope)측정 결과에 의해 결정되었다. AFM에 의해 얻어진 표면 평활도의 개념은 사파이어 기판을 사용한 GaN박막성장의 최적조건을 결정하는 데 있어서 높은 신뢰도를 가질 수 있다.

• Journal of the Korean Ceramic Society
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• v.53 no.4
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• pp.463-467
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• 2016

$Si^{4+}-N^{3-}$ was incorporated into $Ce^{3+}-doped$ lutetium aluminum garnet ($Lu_{2.965}Ce_{0.035}Al_5O_{12}$, $LuAG:Ce^{3+}$) lattices, resulting in the formation of $Lu_{2.965}Ce_{0.035}Al_{5-x}Si_xO_{12-x}N_x$ [(Lu,Ce)AG:xSN]. For x = 0-0.25, the synthesized powders consisted of the LuAG single phase, and the lattice constant decreased owing to the smaller $Si^{4+}$ ions. However, for x > 0.25, a small amount of unknown impurity phases was observed, and the lattice constant increased. Under 450 nm excitation, the PL spectrum of $LuAG:Ce^{3+}$ exhibited the green band, peaking at 505 nm. The incorporation of $Si^{4+}-N^{3-}$ into the $Al^{3+}-O^{2-}$ sites of $LuAG:Ce^{3+}$ led to a red-shift of the emission peak wavelength from 505 to 570 nm with increasing x. Corresponding CIE chromaticity coordinates varied from the green to yellow regions. These behaviors were discussed based on the modification of the $5d^1$ split levels and crystal field surroundings of $Ce^{3+}$, which arose from the Ce-(O,N)8 bonds.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.20 no.1
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• pp.1-7
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• 2007

In this paper, two kinds of initial oxidation methods i.e., SLTO(Slow Low Temperature Oxidation: $700^{\circ}C$) and RTO(Rapid Thermal Oxidation: $850^{\circ}C$) are applied prior to the plasma nitridation for ultra thin oxide of RPNO (Remote Plasma Nitrided Oxide). It is observed that SLTO has superior characteristics to RTO such as lower SS(Sub-threshold Slope) and improved Ion-Ioff characteristics. Low frequency noise characteristics of SLTO also showed better than RTO both in linear and saturation regime. It is shown that flicker noise is dominated by carrier number fluctuation in the channel region. Therefore, SLTO is promising for nano-scale CMOS technology with ultra thin gate oxide.

• Electrical & Electronic Materials
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• v.16 no.9
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• pp.65.1-65
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• 2003

The interface of zirconium oxide thin films on silicon is analyzed in detail for their potential applications in the microelectronics. The formation of an interfacial layer of ZrSi$\sub$x/O$\sub$y. with graded Zr concentration is observed by the x-ray photoelectron spectroscopy and secondary ion mass spectrometry analysis. The as-deposited ZrO$_2$/ZrSi$\sub$x/O$\sub$y//Si sample is thermally stable up to 880$^{\circ}C$, but is less stable compared to the ZrO$_2$/SiO$_2$/Si samples. Post-deposition annealing in oxygen or ammonia improved the thermal stability of as-deposited ZrO$_2$/ZrSi$\sub$x/O$\sub$y/Si to 925$^{\circ}C$, likely due to the oxidation/nitridation of the interface. The as-deposited film had an equivalent oxide thickness of∼13 nm with a dielectric constant of ∼21 and a leakage current of 3.2${\times}$10e-3 A/$\textrm{cm}^2$ at 1.5V. Upon oxygen or ammonia annealing, the formation of SiO$\sub$x/ and SiH$\sub$x/N$\sub$y/O$\sub$z/ at the interface reduced the overall dielectric constants.

• Journal of the Korean Ceramic Society
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• v.26 no.5
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• pp.637-644
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• 1989

Beta-sialon powder(Z=1) was synthesized by the simultaeous reduction and nitridation of the mixed powders of Hadong kaolin and silica. Silicon hydroxide was prepared from Si-alkoxide by a hydrolysis method and amorphous silica was obtained from the calcination of the prepared silicon hydroxide. Hadong kaolin was mixed with both the silicon hydroxide and amorphous silica, respectively. The average particle size was 4${\mu}{\textrm}{m}$ and the morphology of particle was rod-like and equiaxed in the case of beta-sialon powder prepared form Hadong kaolin and silicon hydroxide(COMPOSITION A), whereas the average particle size was 3${\mu}{\textrm}{m}$ and the morphology of particle was equiaxed in the case of beta-sialon powder prepared from Hadong kaolin and amorphous silica(COMPOSITION B). The synthesized beta-sialon powders were hot-pressed at 175$0^{\circ}C$ for 2 hours under 30 MPa in a nitrogen atmosphere after YAG composition(8wt%) was added to these powders as a sintering agent. The hot-pressed specimens were annealed a 140$0^{\circ}C$ for 4 hours in a nitrogen atmosphere. The mechanical properties of sintered bodies were investigated in terms of M.O.R., fracture toughness and hardness. The measured values are as follows. COMPOSITION A : M.O.R. 508MPa, KIC 3.5MN/m3/2, hardness 13.6GPa. COMPOSITION B : M.O.R. 653MPa, KIC 5.4MN/m3/2, hardness 13.5GPa.

• Journal of the Korean Society for Heat Treatment
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• v.8 no.3
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• pp.187-196
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• 1995

TiN and AlN are ceramic materials with mechanical and chemical properties for use in structural applications at elevated temperature. The purpose of this research is to develop the technology for the synthesis of (Ti, Al)N power, which shows simultancously the excellent properties of TiN and AlN, from the mixed powder($Ti_{0.25}Al_{0.75}$, $Ti_{0.5}Al_{0.5}$ and $Ti_{0.75}Al_{0.25}$) by the direct nitriding method. The effects of variables such as temperature, mixing ratio of Al to Ti in raw material were investigated. The(Ti, Al)N powder can be easily synthesized from the mixed powder by the direct nitriding method. Among the mixed powdres, the nitriding behavior decreased with increasing the ratio of Al to Ti. This behavior is well explained by the nitriding mechanism presented in this research.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.7
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• pp.576-582
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• 2002

Nonvolatile semiconductor memory devices with reoxidized nitrided oxide(RONO) gate dielectrics were fabricated, and nitrogen distribution and bonding species which contribute to memory characteristics were analyzed. Also, memory characteristics of devices depending on the anneal temperatures were investigated. The devices were fabricated by retrograde twin well CMOS processes with $0.35\mu m$ design rule. The processes could be simple by in-situ process in growing dielectric. The nitrogen distribution and bonding states of gate dielectrics were investigated by Dynamic Secondary Ion Mass Spectrometry(D-SIMS), Time-of-Flight Secondary Ion Mass Spectrometry(ToF-SIMS), and X-ray Photoelectron Spectroscopy(XPS). As the nitridation temperature increased, nitrogen concentration increased linearly, and more time was required to form the same reoxidized layer thickness. ToF-SIMS results showed that SiON species were detected at the initial oxide interface which had formed after NO annealing and $Si_2NO$ species within the reoxidized layer formed after reoxidation. As the anneal temperatures increased, the device showed worse retention and degradation properties. It could be said that nitrogen concentration near initial interface is limited to a certain quantity, so the excess nitrogen is redistributed within reoxidized layer and contribute to electron trap generation.