• Korean Journal of Crystallography
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• v.12 no.3
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• pp.182-187
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• 2001

The purpose of this study is to investigate the degradation of soft magnetic properties of Fe-Hf-N thin films after annealing in vacuum. They were annealed at 450℃∼650℃. The microstructure and crystal phase of the selected area of the thin films were analyzed by TEM and SAD. After annealing at 450℃-600℃, the coercivity of the films increased by 0.2 Oe and the effective permeability decreased by 1500 as compared with them before annealing due to the growth of α-Fe crystallites. The saturation magnetic flux density of the films increased by 0.5 KG after annealing under 600℃. However, the soft magnetic properties of the film annealed at 650℃ degraded abruptly, which was attributed to the destruction of nano-crystalline microstructure of the film due to the rapid growth of α-Fe crystallites with the segregation of N sited in the α-Fe lattice into HfN.

• Korean Journal of Materials Research
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• v.21 no.1
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• pp.28-33
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• 2011

This paper describes the fabrication of AlN thin films containing iron and iron nitride particles, and the magnetic and electrical properties of such films. Fe-N-Al alloy films were deposited in Ar and $N_2$ mixtures at ambient temperature using Fe/Al composite targets in a two-facing-target DC sputtering system. X-ray diffraction results showed that the Fe-N-Al films were amorphous, and after annealing for 5 h both AlN and bcc-Fe/bct-$FeN_x$ phases appeared. Structure changes in the $FeN_x$ phases were explained in terms of occupied nitrogen atoms. Electron diffraction and transmission electron microscopy observations revealed that iron and iron nitride particles were randomly dispersed in annealed AlN films. The grain size of magnetic particles ranged from 5 to 20 nm in diameter depending on annealing conditions. The saturation magnetization as a function of the annealing time for the $Fe_{55}N_{20}Al_{25}$ films when annealed at 573, 773 and 873 K. At these temperatures, the amount of iron/iron nitride particles increased with increasing annealing time. An increase in the saturation magnetization is explained qualitatively in terms of the amount of such magnetic particles in the film. The resistivity increased monotonously with decreasing Fe content, being consistent with randomly dispersed iron/iron nitride particles in the AlN film. The coercive force was evaluated to be larger than $6.4{\times}10^3Am^{-1}$ (80 Oe). This large value is ascribed to a residual stress restrained in the ferromagnetic particles, which is considered to be related to the present preparation process.

• Journal of Ceramic Processing Research
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• v.13 no.spc1
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• pp.149-153
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• 2012

Ti2AlN MAX-phase films were synthesized through the post-annealing process of as-deposited Ti-Al-N films. Near amorphous or quasi-crystalline ternary Ti-Al-N films were deposited on Si and Al2O3 substrates by sputtering a Ti2AlN MAX-phase target at room temperature, 300 ℃ and 450 ℃, respectively. A vacuum annealing of those films at 800 ℃ for 1 hour changed those films to crystalline Ti2AlN MAX-phase. The polycrystalline Ti2AlN MAX-phase films exhibited very excellent oxidation resistance due to its characteristics microstructure (nanolaminates), which has potential applications for high-temperature protective coatings. The microstructure and composition of Ti2AlN MAX-phase films were investigated using with a variety of characterization tools.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.2
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• pp.152-155
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• 2011

Even though nano-scale materials were very advantageous for various applications, there are still problems to be solved such as the stabilization of surface state and realization of low contact resistances between a semiconducting nanowire and electrodes in nano-electronics. It is well known that the effects of contacts barrier between nano-channel and metal electrodes were dominant in carrier transportation in individual nano-electronics. In this report, it was investigated the electrical properties of GaN nanorod devices after chemical etching and rapid thermal annealing for making good contacts. After KOH wet-etching of the contact area the devices showed better electrical performance compared with non-treated GaN individual devices but still didn't have linear voltage-current characteristics. The shape of voltage-current properties of GaN devices were improved remarkably after rapid thermal annealing as showing Ohmic behaviors with further bigger conductivities. Even though chemical etching of the nanorod surfaces could cause scattering of carriers, in here it was shown that the most important and dominant factor in carrier transport of nano-electronics was realization of low contact barrier between nano-channel and metal electrodes surely.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.12
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• pp.1091-1098
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• 1998

Thermal stability of the electroless deposited Cu thin film was investigated. Cu/TaN/Si multilayer was fabricated by electroless-depositing Cu thin layer on TaN diffusion barrier layer which was deposited by MOCVD on the Si substrate, and was annealed in $H_2$ ambient to investigate the microstructure of Cu film with a post heat-treatment. Cu thin film with good adhesion was successfully deposited on the surface of the TaN film by electroless deposition with a proper activation treatment and solution control. Microstructural property of the electroless-deposited Cu layer was improved by a post-annealing in the reduced atmosphere of $H_2$ gas up to $600^{\circ}C$. Thermal stability of Cu/TaN/Si system was maintained up to $600^{\circ}C$ annealing temperature, but the intermediate compounds of Cu-Si were formed above $650^{\circ}C$ because Cu element passed through the TaN layer. On the other hand, thermal stability of the Cu/TaN/Si system in Ar ambient was maintained below $550^{\circ}C$ annealing temperature due to the minimal impurity of $O_2$ in Ar gas.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.30A no.8
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• pp.34-41
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• 1993

Effect of high temperature annealing conditions on Ta$_{2}O_{5}$ thin films was investigated. Ta$_{2}O_{5}$ thin films were deposited on P-type silicon substrates by plasma-enhanced chemical vapor deposition (PECVD) using tantalum ethylate. Ta(C$_{2}H_{5}O)_{5}$, and nitrous oxide. N$_{2}$O. The microstructure changed from amorphous to polycrystalline above 700.deg. C annealing temperature. The refractive index, dielectric onstant and leakage current of the film increased as annealing temperature increased. However, annealing in oxygen ambient reduced leakage currents and dielectric constant due to the formation of interfacial SiO$_{2}$ layer. By optimizing annealing temperature and ambient, leakage current lower than 10$^{-8}$ A/cm$^{2}$ and maximum capacitance of 9 fF/${\mu}m^{2}$ could be obtained.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.570-573
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• 2001

In this paper, GaN films have been grown on SiO$_2$/Si(100) substrates by RF magnetron sputtering. To obtain high quality GaN films, we used ZnO buffer layer and modified the process conditions. The charateristics of GaN films on RF power, substrate temperature and Ar/N$_2$gas ratio have been investigated by Auger electron spectroscopy and X-ray diffraction analysis. At RF power 150W, substrate temperature 500 $^{\circ}C$ and Ar/N$_2$=1:2 gas ratio, we could grow high quality GaN films. Through the atomic force microscope and photoluminescence analysises, it was observed that the crystallization of GaN films was improved with increasing annealing temperature and the optimal crystallization of GaN films was found at 1100 $^{\circ}C$ annealing temperature.

• Journal of the Korean institute of surface engineering
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• v.31 no.5
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• pp.237-244
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• 1998

In this stydy, submicron shallow trenches applied to STI(shallow tench isolation) were etched using inductively coupled $CI_2$/HBr and $CI_2/N_2$plasmas and the physical and electrical defects remaining on the etched silicon trench surfaces and the effects of various annealing and oxidation on the removal of the defects were studied. Using high resolution electron microscopy(HRTEM), Physical defects were investigated on the silicon trench surfaces etched in both 90%$CI_2$/ 10%$N_2$ and 50%$CI_2$/50%HBr. Among the areas in the tench such as trench bottom, bottom edge, and sidewall, the most dense defects were found near the trench bottom edge, and the least dense defects were found near the trench bottom edge, and least dense defects compared to that etched with ment as well as hydrogen permeation. Thermal oxidation of 200$\AA$ atthe temperature up to $1100^{\circ}C$apprars not to remove the defects formed on the etched silicon trenches for both of the etch conditions. To remove the physicall defects, an annealing treatment at the temperature high than $1000^{\circ}C$ in N for30minutes was required. Electrical defects measured using a capacitance-voltage technique showed the reduction of the defects with increasing annealing temperature, and the trends were similar to the results on the physical defects obtained using transmission electron microscopy.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.574-577
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• 2001

GaN thin films on sapphire were grown by rf magnetron sputtering with ZnO buffer layer. The dependence of GaN film quality on ZnO buffer layer was investigated by X-ray diffraction(XRD). The improved film quality has been obtained by using thin ZnO buffer layer. Using Auger electron spectroscopy(AES), it was observed that the annealing process improved the GaN film quality. The surface roughness according to the annealing temperatures(700, 900, 1100$^{\circ}C$) were investigated by AFM(atomic force microscopy) and it was confirmed that the crystallization was improved by increasing the annealing temperature. Photoluminescence at 8K shows a near-band-edge peak at 3.2eV with no deep level emission.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.292-292
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• 2014

Wide band gap semiconductors, such as III-nitrides (GaN, AlN, InN, and their alloys), SiC, and diamond are expected to play an important role in the next-generation electronic devices. Specifically, GaN-based high electron mobility transistors (HEMTs) have been targeted for high power, high frequency, and high temperature operation electronic devices for mobile communication systems, radars, and power electronics because of their high critical breakdown fields, high saturation velocities, and high thermal conductivities. For the stable operation, high power, high frequency and high breakdown voltage and high current density, the fabrication methods have to be optimized with considerable attention. In this study, low ohmic contact resistance and smooth surface morphology to AlGaN/GaN on 2 inch c-plane sapphire substrate has been obtained with stepwise annealing at three different temperatures. The metallization was performed under deposition of a composite metal layer of Ti/Al/Ni/Au with thickness. After multi-layer metal stacking, rapid thermal annealing (RTA) process was applied with stepwise annealing temperature program profile. As results, we obtained a minimum specific contact resistance of $1.6{\times}10^{-7}{\Omega}cm2$.