• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.11a
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• pp.633-636
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• 1999

In this study, we have fabricated amorphous FeZrBAg thin films with low core losses by using DC magnetron sputtering method. After deposition, rotational field annealing (RFA) method was performed in the dc field of 1.5 kOe. The amorphous FeZrBAg thin films produced by annealing at 35$0^{\circ}C$ was founded to have high permeability of 8680 at 100 MHz, 0.2 mOe, low coercivity of 0.86 Oe high magnetization of 1.5 T and very low core loss of 1.3 W/cc at 1 MHz, 0.IT respectively. Excellent soft magnetic properties in a amorphous FeZrBAg thin films in the present study are presumably the homogeneous formation of very fine bcc $\alpha$-Fe crystalline with the 8.2 nm in an amorphous FeZrBAg thin film matrix.

• Journal of Magnetics
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• v.2 no.3
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• pp.76-85
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• 1997

Magnetic and magnetostrictive properties of Tb-Fe and Tb-Fe-B thin films are systematically investigated over a wide composition range from 40.2 to 68.1 at. % Tb. The films were fabricated by rf magnetron sputtering using a composite target which consists of an Fe plate and Tb chips. The microstructure, examined by X-ray diffraction, mainly consists of an amorphous phase and, at high Tb contents, a pure Tb phase also exists. A progressive change in the direction of anisotropy from the perpendicular to in-plane occurs as the Tb content increases and the boundary at which the anisotropy change occurs shifts significantly towards to higher Tb contents with the addition of B. The saturation magnetization exhibits maxima at the Tb contents of 42 and 48 at. % for Tb-Fe and Tb-Fe-B thin films, respectively, and it is decreased by the addition of B. The coercive force, measured in the easy direction, decreases monotonically with the Tb content. Excellent magnetostrictive characteristics, particularly at low magnetic fields, are achieved in both Tb-Fe and Tb-Fe-B thin films; for example, a magnetostriction of 138 ppm is obtained in a Tb-Fe-B thin film at a magnetic field as low as 30 Oe. The excellent magnetostrictive properties of the present thin films are supported by the equally excellent magnetic softness, the coercivity below 10 Oe and a typical squared-loop shape with the saturation field as low as 1 kOe. Due to the excellent low field magnetostrictive characteristics, the present Tb-Fe based thin films are thought to be suitable for Si based microdevices.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.11
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• pp.963-968
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• 2000

Magnetic properties and microstructures of Fe$\_$93-x/Zr$_3$B$_4$Ag$\_$x/ thin films were investigated as a function of addition of element Ag, (X$\_$Ag/=0 to 6 at.%) and annealing temperature, T$\_$a/=300$\^{C}$ to 600$\^{C}$. In the case of adding Ag, magnetic properties of Fe$\_$93-x/Zr$_3$B$_4$Ag$\_$x/ thin films were improved than those of Ag-free Fe$\_$93/Zr$_3$B$_4$thin films. The prominent soft magnetic properties with coercivity of 1.1 Oe, saturation magnetization of 2.2 T and permeability of 5400 at 50㎒ were obtained from Fe$\_$88/Zr$_3$B$_4$Ag$\_$5/ thin film annealed was lower than that of Fe-base or Co-base thin films reported previously. Such enhanced magnetic properties are presumably attributed to the format in ultra fine grains. Also, the reduced eddy current loss in the annealed sample is due to refined micro magnetic domains with increasing the amount of Ag in Fe$\_$93-x/Zr$_3$B$_4$Ag$\_$x/ thin films.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.04a
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• pp.3-6
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• 2002

Effect of Ag additive element on microstructure of $Fe_{87-x}Zr_7B_6Ag_x$, magnetic thin films on Si(001) substrates has been investigated using Transmission Electron Microscopy(TEM) and X-ray Diffraction(XRD). All samples with additive Ag element were made by DC-sputtering and subjected to annealing treatments of $300^{\circ}C{\siim}600^{\circ}C$ for 1 hr. TEM and XRD showed that perfectly amorphous state in Ag-free Fe-based films was observed in as-deposited condition. The as-deposited Fe-based films with the presence of Ag constituent have a mixture of Fe-based amorphous and nano-sized Ag crystalline phases. In this case, additive element, Ag was soluted into Fe-based matrix. With the increase in additive element, Ag, insoluble nano-crystalline Ag particles were dispersed in the Fe-based amorphous matrix. Crystallization of Fe-based amorphous phase in the matrix of $Fe_{82}Zr_7B_6Ag_5$ thin films occurred at an annealing temperature of $400^{\circ}C$. Upon annealing, the amorphous-Ag crystalline state of Fe-Zr-B-Ag films was transformed into the mixture of Ag crystalline phase + Fe-based amorphous phase + ${\alpha}$-Fe cluster followed by the crystallization process of ${\alpha}$-Fe nanocrystalline + Ag crystalline phases.

• Bulletin of the Korean Chemical Society
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• v.27 no.10
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• pp.1633-1637
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• 2006

We demonstrate a selective vapor-phase deposition of conductive poly(3,4-ethylenedioxythiophene) (PEDOT) thin films on patterned $FeCl_3$. The PEDOT thin films were grown on various substrates by using the vapor-phase polymerization of ethylenedioxythiophene (EDOT) with $FeCl_3$ catalytic layers at 325 K. The selective deposition of the PEDOT thin films using vapor-phase polymerization was accomplished with patterned $FeCl_3$ layers as templates. Microcontact printing was done to prepare patterned $FeCl_3$ on polyethyleneterephthalate (PET) substrates. The selective vapor-phase deposition is based on the fact that the PEDOT thin films are selectively deposited only on the regions exposing $FeCl_3$ of the PET substrates, because the EDOT monomer can be polymerized only in the presence of oxidants, such as $FeCl_3$, Fe($CIO_4$), and iron(II) salts of organic acids/inorganic acids containing organic radicals.

• Progress in Superconductivity
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• v.12 no.1
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• pp.32-35
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• 2010

Potassium doped $BaFe_2As_2$ superconducting thin films by using an ex situ pulsed laser deposition technique were fabricated in various conditions to find out an optimal growth condition. Controlled conditions were annealing temperature, annealing time, and mass of potassium. The $Ba_{1-x}K_xFe_2As_2$ thin films which has most good quality is fabricated at a condition of annealing temperature at $700^{\circ}C$, annealing time of 60 minutes, and 0.6 g of potassium lumps. In this condition we were able to fabricate good quality films with high transition temperature of ~ 39 K.

• Journal of the Korean Magnetics Society
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• v.5 no.5
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• pp.538-542
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• 1995

The etching characteristics of magnetic thin films of permalloy and Fe-based alloys are investigated. The thin films are fabricated by rf magnetron sputtering and the substrates used are silicon and glass. Etching is done by ion beam technique and the main process parameters investigated are beam voltage, beam current and accelerating voltage. The etch rate of the magnetic films is proportional to the beam current, but it is not directly related to the accelerating voltage and beam voltage. The dependence of etch rate on the process parameters can be explained by ion current density. It is found that the ion beam etching is effective in obtaining well-developed micro-patterns on the permalloy and Fe- based magnetic thin films.

• Progress in Superconductivity and Cryogenics
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• v.16 no.3
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• pp.4-6
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• 2014

Among Fe-based superconductors, potassium doped $BaFe_2As_2$ is favorable for applications because of its relatively high transition temperature and low anisotropy. To study the superconducting properties and the applicable aspects, high quality thin films of potassium doped $BaFe_2As_2$ should be fabricate. However, the high volatility of potassium makes it difficult to fabricate thin films of this compound. In this paper, we discuss the details of the experimental conditions used to fabricate $Ba_{1-x}K_xFe_2As_2$ films by ex situ PLD method. In the first set of samples, barium ratio in the target was controlled to make films with various potassium doping rate. However, in the second set of samples, the amount of potassium was controlled to find out optimal conditions for making high quality $Ba_{1-x}K_xFe_2As_2$ films.

• Bulletin of the Korean Chemical Society
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• v.16 no.6
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• pp.511-515
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• 1995

Since much studies have been performed concerning the electrochemical behaviors and the practical applications of PB based devices, little has yet reported to investigate the best condition for the preparation for PB thin films. As considered some factors(peak shape, peak current, and peak separation) from the i-V curves, the optimal condition in the film growth were investigated under various immersion solutions. An electron-transfer processes of Fe2+/Fe3+ and Fe(CN)63-/4- redox couples were considered by measuring the observed currents as a function of the rotation velocity. The standard heterogeneous electron-transfer rates for these films and bare Au disc electrode in 10-3 M Fe2+/Fe3+ solution, applied at +0.65 V vs. SCE, were 6.14 × 10-3 and 7.78 × 10-3 cm/s, respectively, obtained using a rotating disc electrode. In case of the addition of potassium ion, the rate constants for these Fe2+/Fe3+ system on thin films of PB and bare electrode were given a little high values. The electron transfer rate for 10-3 M Fe(CN)63-/4- were 4.55 × 10-3 and 6.84 × 10-3 cm/s, respectively. The conductivity as directly determined during obtained the voltammogram, was 2.2 × 10-7 (Ω·cm)-1. This value is similar magnitude to that calculated from bulk sample.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.233-233
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• 2010

Magnetic random access memory (MRAM), based on magnetic tunnel junction (MTJ) and CMOS, is a prominent candidate among prospective semiconductor memories because it can provide nonvolatility, fast access time, unlimited read/write endurance, low operating voltage and high storage density. The etching of MTJ stack with good properties is one of a key process for the realization of high density MRAM. In order to achieve high quality MTJ stack, the use of CoFeB and IrMn magnetic films as free layers was proposed. In this study, inductively coupled plasma reactive ion etching of CoFeB and IrMn thin films masked with Ti hard mask was investigated in a $Cl_2$/Ar gas mix. The etch rate of CoFeB and IrMn films were examined on varying $Cl_2$ gas concentration. As the $Cl_2$ gas increased, the etch rate monotonously decreased. The effective of etch parameters including coil rf power, dc-bais voltage, and gas pressure on the etch profile of CoFeB and IrMn thin film was explored, At high coil rf power, high dc-bais voltage, low gas pressure, the etching of CoFeB and IrMn displayed better etch profiles. Finally, the clean and vertical etch sidewall of CoFeB and IrMn free layers can be achieved by means of thin Ti hard mask in a $Cl_2$/Ar plasma at the optimized condition.