• Proceedings of the Korean Vacuum Society Conference
• /
• 2008.08a
• /
• pp.112-112
• /
• 2008

• Korean Journal of Materials Research
• /
• v.23 no.12
• /
• pp.714-721
• /
• 2013

A stoichiometric mixture of evaporating materials for $ZnAl_2Se_4$ single-crystal thin films was prepared in a horizontal electric furnace. These $ZnAl_2Se_4$ polycrystals had a defect chalcopyrite structure, and its lattice constants were $a_0=5.5563{\AA}$ and $c_0=10.8897{\AA}$.To obtain a single-crystal thin film, mixed $ZnAl_2Se_4$ crystal was deposited on the thoroughly etched semi-insulating GaAs(100) substrate by a hot wall epitaxy (HWE) system. The source and the substrate temperatures were $620^{\circ}C$ and $400^{\circ}C$, respectively. The crystalline structure of the single-crystal thin film was investigated by using a double crystal X-ray rocking curve and X-ray diffraction ${\omega}-2{\theta}$ scans. The carrier density and mobility of the $ZnAl_2Se_4$ single-crystal thin film were $8.23{\times}10^{16}cm^{-3}$ and $287m^2/vs$ at 293 K, respectively. To identify the band gap energy, the optical absorption spectra of the $ZnAl_2Se_4$ single-crystal thin film was investigated in the temperature region of 10-293 K. The temperature dependence of the direct optical energy gap is well presented by Varshni's relation: $E_g(T)=E_g(0)-({\alpha}T^2/T+{\beta})$. The constants of Varshni's equation had the values of $E_g(0)=3.5269eV$, ${\alpha}=2.03{\times}10^{-3}eV/K$ and ${\beta}=501.9K$ for the $ZnAl_2Se_4$ single-crystal thin film. The crystal field and the spin-orbit splitting energies for the valence band of the $ZnAl_2Se_4$ were estimated to be 109.5 meV and 124.6 meV, respectively, by means of the photocurrent spectra and the Hopfield quasicubic model. These results indicate that splitting of the ${\Delta}so$ definitely exists in the ${\Gamma}_5$ states of the valence band of the $ZnAl_2Se_4/GaAs$ epilayer. The three photocurrent peaks observed at 10 K are ascribed to the $A_1$-, $B_1$-exciton for n = 1 and $C_{21}$-exciton peaks for n = 21.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.22 no.7
• /
• pp.549-554
• /
• 2009

Al thin films were synthesized on TiN/Si substrate by MOCVD using N-methylpyrrolidine alane (MPA) precursor. Effects of substrate temperature, reaction pressure on the deposition rate, surface roughness and electrical resistivity were investigated. The early stage of Al thin film formation was analyzed by in-situ surface reflectivity measurement with a laser and photometer apparatus. From the Arrhenius plot of deposition rate vs. substrate temperature, it was found that the activation energy of surface reaction was 91.1kJ/mole, and the transition temperature from surface-reaction-limited region to mass-transfer-limited region was about $150^{\circ}C$. The growth rate increased with the reaction pressure, and average growth rates of $200{\sim}1,200nm/min$ were observed at various experimental conditions. Surface roughness of the film increased with the film thickness. The electrical resistivity of Al film was about $4{\mu}{\Omega}{\cdot}cm$ in the case of optimum condition, and it was close to the value of the bulk Al, $2.7{\mu}{\Omega}{\cdot}cm$.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2004.08a
• /
• pp.657-659
• /
• 2004

Trivalent cerium ($Ce^{3+}$) activated yttrium aluminum garnet ($Y_3Al_5O_{12}$, YAG) phosphor thin films were deposited on quartz glass substrates by rf magnetron sputtering. The effects of sputtering parameters and annealing condition on the luminescent properties were investigated. The sputtering parameters were $O_2$/Ar gas ratio, rf power, and deposition time. The films were annealed at 1200 $^{\circ}C$ for 5 hours in $N_2+$vacuum atmosphere. Polycrystalline YAG:Ce thin film phosphor could be obtained with a gas ratio of $O_2$/(Ar+$O_2$)=0.5 after post-annealing. PL spectra excited at 450 nm showed a yellow single band at 550 nm.

• Proceedings of the Korean Institute of Surface Engineering Conference
• /
• 2007.11a
• /
• pp.136-137
• /
• 2007

Wear resistant TiAlN thin film has been widely deposited on the surface of cutting and forming tools by using Arc Ion Plating. TiAlN films are deposited by the processes designed by the Taguchi L18 experimental design. The L18 experimental design is applied to achieve surface properties and adhesion. The deposition parameters are working pressure, substrate temperature, bias voltage, arc power and pre-sputtering bias voltage and time. The most influential parameters on surface properties and adhesion are substrate bias voltage, working nitrogen pressure and arc power. The optimal coating processes are obtained for surface properties and adhesion.

• Proceedings of the Korean Magnestics Society Conference
• /
• 1991.05a
• /
• pp.73-74
• /
• 1991

The films with ferromagnetic fine particles dispersed in nonmagnetic matrix, such as $Fe-Al_2O_3$ and Fe-Cu have been studied for use of magnetic recording medium, optically device and sensor. Their magnetic properties depend strongly on structural parameter such as size and volume fraction of ferromagnetic particles. Fe-Cr-Ni alloy sputtered films also have microstructure with ferromagnetic -- b.c.c phase and nonmagnetic f.c.c phase grains. Magnetic properties of these films depend strongly on such a unique structure. These are depend on the ratio in volume of ferromagnetic particles to nonmagnetic ones $V_F/V_N$, the saturation magnetization Ms increased with increase of $V_F/V_N$. The coercivity Hc of the as-deposited films took maximum value of about 200 Oe at adequate $V_F/V_N$ and then Ms and Squareness S were 500 emu/cc and 0.5, respectively.(omitted)

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.19 no.8
• /
• pp.775-779
• /
• 2006

In this study, sputtered $Al_2O_3$ thin films were evaluated as a passivation layer in the process of InGaN-based blue LEDs in order to improve the brightness of LED lamps. In terms of packaged LED lamps, lamps with $Al_2O_3$ passivation layer emanated higher brightness than those with $SiO_2$ passivation layer, and LED lamps with 90 nm $Al_2O_3$ passivation layer were the brightest among four kinds of lamps. Although lamps with $Al_2O_3$ passivation had a slight increase in operating voltage, their brightness was improved about 13.6 % compare to the lamps made of conventional LEDs without the changes of emitting wavelength.

• Journal of the Korean Institute of Telematics and Electronics A
• /
• v.31A no.10
• /
• pp.108-113
• /
• 1994

The characteristics of the oxidation prevention layers for the copper metallization were investigated. The thin films such as Cr, TiN and Al were used as the oxidation prevention layers for copper. Ultra thin aluminum films were found to prevent the oxidation of copper up to the highest oxidation annealing temperature among the barrier layers examined in this study. It was found that oxygen did not diffuse into copper through aluminum films because of the aluminum oxide layer formed on the aluminum surface and the ultra thin aluminum film could be a good oxidation barrier layer for the copper metallization.

• Journal of the Korean Magnetics Society
• /
• v.15 no.1
• /
• pp.17-20
• /
• 2005

The influence of $O_2$ partial pressure on saturation mgnetization, coercivity, anisotropy field and effective permeability (over 1GHz) of as-deposited Co-Fe-Al-O thin films, which were fabricated by RF magnetron reactive sputtering method, were investigated. The $Co_{69.9}Fe_{20.5}A_{14.4O_{5.2}$ thin film fabricated at $O_2$ partial pressure of 4% exhibits the best magnetic softness with saturation magnetization 4${$pi}$Ms of 18.1 kG, coercivity of 0.82 Oe, anisotropy field ($H_k$) of Oe, and effective permeability (${\mu}_{eff}$) about 1,024 above 1 GHz. the electrical resistivity of Co-Fe-Al-O thin films were increased with increasing $O_2$ partial pressure, the electrical resistivity of $Co_{69.9}Fe_{20.5}A_{14.4O_{5.2}$ thin film with the best soft magnetic properties was 560.7 ${\mu}{\Omega}$am. Therefore, It is assumed that the good soft magnetic properties of $Co_{69.9}Fe_{20.5}A_{14.4O_{5.2}$ thin film results from high electrical resistivity and large anisotropy field.

• Proceedings of the Korean Institute of Surface Engineering Conference
• /
• 1999.10a
• /
• pp.56-56
• /
• 1999

For advanced TFT-LCD manufacturing processes, dry etching of thin-film layers(a-Si, $SiN_x$, SID & gate electrodes, ITO etc.) is increasingly preferred instead of conventional wet etching processes. To dry etch Al gate electrode which is advantageous for reducing propagation delay time of scan signals, high etch rate, slope angle control, and etch uniformity are required. For the Al gate electrode, some metals such as Ti and Nd are added in Al to prevent hillocks during post-annealing processes in addition to gaining low-resistivity($<10u{\Omega}{\cdot}cm$), high performance to heat tolerance and corrosion tolerance of Al thin films. In the case of AI-Nd alloy films, however, low etch rate and poor selectivity over photoresist are remained as a problem. In this study, to enhance the etch rates together with etch uniformity of AI-Nd alloys, magnetized inductively coupled plasma(MICP) have been used instead of conventional ICP and the effects of various magnets and processes conditions have been studied. MICP was consisted of fourteen pairs of permanent magnets arranged along the inside of chamber wall and also a Helmholtz type axial electromagnets was located outside the chamber. Gas combinations of $Cl_2,{\;}BCl_3$, and HBr were used with pressures between 5mTorr and 30mTorr, rf-bias voltages from -50Vto -200V, and inductive powers from 400W to 800W. In the case of $Cl_2/BCl_3$ plasma chemistry, the etch rate of AI-Nd films and etch selectivity over photoresist increased with $BCl_3$ rich etch chemistries for both with and without the magnets. The highest etch rate of $1,000{\AA}/min$, however, could be obtained with the magnets(both the multi-dipole magnets and the electromagnets). Under an optimized electromagnetic strength, etch uniformity of less than 5% also could be obtained under the above conditions.