• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.257-265
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• 2002

A stoichiometric mixture of evaporating materials for AgInS$_2$ single crystal thin films was prepared from horizontal furnace. To obtain the single crystal thin films, AgInS$_2$ mixed crystal was deposited on thoroughly etched semi-insulating GaAs(100) substrate by the Hot Wall Epitaxy(HWE) system. The source and substrate temperatures were 680 $^{\circ}C$ and 410 $^{\circ}C$, respectively. The crystalline structure of the single crystal thin films was investigated by the photoluminescence and double crystal X-ray diffraction(DCXD). The carrier density and mobility of AgInS$_2$ single crystal thin films measured from Hall effect by van der Pauw method are 9.35${\times}$10$\^$16/ cm$\^$-3/ and 294 $\textrm{cm}^2$/V$.$s at 293 K, respectively. From the optical absorption measurement, the temperature dependence of the energy band gap on AgInS$_2$ single crystal thin films was found to be E$\_$g/(T) : 2.1365 eV - (9.89 ${\times}$ 10$\^$-3/ eV) T$^2$/(2930 + T). After the as-grown AgInS$_2$ single crystal thin films was annealed in Ag-, S-, and In-atmospheres, the origin of point defects of AgInS$_2$ single crystal thin films has been investigated by using the photoluminescence(PL) at 10 K. The native defects of V$\_$AG/, V$\_$S/, Ag$\_$int/, and S$\_$int/ obtained from PL measurements were classified as a donors or acceptors type. And we concluded that the heat-treatment in the S-atmosphere converted AgInS$_2$ single crystal thin films to an optical p-type. Also, we confirmed that In in AgInS$_2$/GaAs did not form the native defects because In in AgInS$_2$ single crystal thin films did exist in the form of stable bonds.

• Journal of the Korean Society of Radiology
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• v.9 no.7
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• pp.439-443
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• 2015

An electrical signals of a conventional radiation medical imaging sensor are obtained by charge integration method. In this study, the polycrystalline cadmium telluride(p-CdTe) film was fabricated by a thermal evaporation method for the photon counting sensor development with excellent resolution in low exposure dose. From the fabricated p-CdTe sensor, the physical properties(SEM, XRD) and the electrical properties(leakage current, x-ray sensitivity, SNR) were evaluated. As a result, the leakage current of below $5nA/cm^2$ and $7{\mu}C/cm^2-R$ of the X-ray sensitivity were showed in below $1V/{\mu}m$. In addition, the signal to noise ratio showed the values of above 5000 at operating voltage.

• Korean Journal of Materials Research
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• v.11 no.4
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• pp.329-334
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• 2001

Microstructures of barrier-type oxide layers on aluminum was studied by XRD, TEM and RBS. Fer formation of oxide layer. aluminum was anodized in a boric acid solution. The thickness of the oxide film subjected to applied voltage increased linearly at ratio of 1.54nm/V. For oxide layer anodized at 300V, amorphous structure of oxide layer was not transformed after heat treatment at 50$0^{\circ}C$ , while for oxide layers anodized at higher voltages the amorphous structure crystallized into a ${\gamma}$-alumina without any heat treatment. It was also found that the amorphous structure of oxide layer formed at 100V transformed into crystalline structure by electron irradiation. The structure was identified as ${\gamma}$-alumina.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.11a
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• pp.74-75
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• 2005

ZnO epilayer were synthesized by the pulesd laser deposition(PLD) process on $Al_2O_3$ substrate after irradiating the surface of the ZnO sintered pellet by the ArF(193 nm) excimer laser. The epilayers of ZnO were achieved on sapphire ($Al_2O_3$) substrate at a temperature of $400^{\circ}C$. The crystalline structure of epilayer was investigated by the photoluminescence. The carrier density and mobility of ZnO epilayer measured with Hall effect by van der Pauw method are $8.27{\times}10^{16}cm^{-3}$ and $299cm^2/V{\cdot}s$ at 293 K, respectively. The temperature dependence of the energy band gap of the ZnO obtained from the absorption spectra was well described by the Varshni's relation, $E_g$(T) = 3.3973 eV - ($2.69{\times}10^{-4}$ eV/K)$T_2$/(T + 463 K). The crystal field and the spin-orbit splitting energies for the valence band of the ZnO have been estimated to be 0.0041 eV and 0.0399 eV at 10 K, respectively, by means of the photocurrent spectra and the Hopfield quasicubic model. These results indicate that the splitting of the $\triangle$so definitely exists in the $\ulcorner_6$ states of the valence band of the ZnO. The three photocurrent peaks observed at 10K are ascribed to the $A_1-$, $B_1-$, and $C_1$-exciton peaks for n = 1.

• Journal of the Korean Vacuum Society
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• v.18 no.5
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• pp.377-383
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• 2009

Aluminum-doped zinc oxide (AZO) thin films were deposited on sapphire substrate by using radio-frequency magnetron sputtering and were performed in the temperature range of $600-900^{\circ}C$ by rapid thermal annealing (RTA). The crystallographic structure and the surface morphology were investigated by using X-ray diffraction and scanning electron microscopy, respectively. The crystallinity of the films was improved with increasing the annealing temperature and the average size of crystalline grains was found to be 50 nm. All the thin films showed an average transmittance of 92% in the wavelength range of 400-1100 nm. As the annealing temperature was increased, the bandgap energy was decreased and the violet photoluminescence (PL) signal at 400 nm replaced the ultraviolet PL signal. The electrical properties of the thin films showed a significant dependence on the annealing temperature.

• Journal of Sensor Science and Technology
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• v.5 no.1
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• pp.63-70
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• 1996

Silicon epitaxial films of submicron level were successfully grown by the RTCVD method. For the growth of silicon epitaxial layers, $SiH_{2}Cl_{2}\;/\;H_{2}$ gas mixtures and various process parameters including $H_{2}$ prebake process were used. The growth conditions were varied to investigate their effects on the interface abruptness of doping profile, the film growth rates and crystalline properties. The crystallinity of the undoped silicon was excellent at the growth temperature of $900^{\circ}C$. The doping profiles were measured by SIMS technique. The abruptness of doping profile would be controlled within about $200{\AA}/decade$ in the structure of undoped Si / $n^{+}-Si$ substrate.

• Journal of Sensor Science and Technology
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• v.14 no.3
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• pp.160-168
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• 2005

ZnO epilayer were synthesized by the pulesd laser deposition(PLD) process on $Al_{2}O_{3}$ substrate after irradiating the surface of the ZnO sintered pellet by the ArF(193 nm) excimer laser. The epilayers of ZnO were achieved on sapphire ($Al_{2}O_{3}$) substrate at a temperature of $400^{\circ}C$. The crystalline structure of epilayer was investigated by the photoluminescence. The carrier density and mobility of ZnO epilayer measured with Hall effect by van der Pauw method are $8.27{\times}1016cm^{-3}$ and $299cm^{2}/V{\cdot}s$ at 293 K, respectively. The temperature dependence of the energy band gap of the ZnO obtained from the absorption spectra was well described by the Varshni's relation, $E_{g}(T)$=3.3973 eV-($2.69{\times}10^{-4}$ eV/K)$T^{2}$/(T+463K). The crystal field and the spin-orbit splitting energies for the valence band of the ZnO have been estimated to be 0.0041 eV and 0.0399 eV at 10 K, respectively, by means of the photocurrent spectra and the Hopfield quasicubic model. These results indicate that the splitting of the ${\Delta}so$ definitely exists in the ${\Gamma}_{6}$ states of the valence band of the ZnO. The three photocurrent peaks observed at 10 K are ascribed to the $A_{1}-$, $B_{1}-$, and $C_{1}-$exciton peaks for n = 1.

• ETRI Journal
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• v.16 no.1
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• pp.45-57
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• 1994

The effects of reactive ion etching (RIE) of $SiO_2$ layer in $CHF_3/C_2F_6$ on the underlying Si surface have been studied by X-ray photoelectron spectroscopy (XPS), secondary ion mass spectrometer, Rutherford backscattering spectroscopy, and high resolution transmission electron microscopy. We found that two distinguishable modified layers are formed by RIE : (i) a uniform residue surface layer of 4 nm thickness composed entirely of carbon, fluorine, oxygen, and hydrogen with 9 different kinds of chemical bonds and (ii) a contaminated silicon layer of about 50 nm thickness with carbon and fluorine atoms without any observable crystalline defects. To search the removal condition of the silicon surface residue, we monitored the changes of surface compositions for the etched silicon after various post treatments as rapid thermal anneal, $O_2$, $NF_3$, $SF_6$, and $Cl_2$ plasma treatments. XPS analysis revealed that $NF_3$ treatment is most effective. With 10 seconds exposure to $NF_3$ plasma, the fluorocarbon residue film decomposes. The remained fluorine completely disappears after the following wet cleaning.

• Journal of the Microelectronics and Packaging Society
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• v.6 no.2
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• pp.13-21
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• 1999

Flip chip assembly directly on organic boards offers miniaturization of package size as well as reduction in interconnection distances resulting in a high performance and cost-competitive Packaging method. This paper describes the investigation of alternative low cost flip-chip mounting processes using electroless Ni/Au bump and anisotropic conductive adhesives/films as an interconnection material on organic boards such as FR-4. As bumps for flip chip, electroless Ni/Au plating was performed and characterized in mechanical and metallurgical point of view. Effect of annealing on Ni bump characteristics informed that the formation of crystalline nickel with $Ni_3$P precipitation above $300^{\circ}C$ causes an increase of hardness and an increase of the intrinsic stress resulting in a reliability limitation. As an interconnection material, modified ACFs composed of nickel conductive fillers for electrical conductor and non-conductive inorganic fillers for modification of film properties such as coefficient of thermal expansion(CTE) and tensile strength were formulated for improved electrical and mechanical properties of ACF interconnection. The thermal fatigue life of ACA/F flip chip on organic board limited by the thermal expansion mismatch between the chip and the board could be increased by a modified ACA/F. Three ACF materials with different CTE values were prepared and bonded between Si chip and FR-4 board for the thermal strain measurement using moire interferometry. The thermal strain of ACF interconnection layer induced by temperature excursion of $80^{\circ}C$ was decreased with decreasing CTEs of ACF materials.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07a
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• pp.393-396
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• 2004

본 논문에서는 완충층용 MgO 박막을 P-type(100)Si 기판위에 작업가스 $Ar:O_2=80:20$, RF 파워 50W, 기판온도 $400^{\circ}C$, 10mtorr의 작업진공에서 $500{\AA}$ 증착하였다. 제작된 MgO/Si 기판위에 RF Magnetron sputtering법으로 작업가스 $Ar:O_2$의 비율을 90:10, 80:20, 70:30으로 변화하면서 $BST(Ba_{0.5}Sr_{0.5}TiO_3)$ 박막을 약 $2000{\AA}$ 증착하였다. XRD 측정결과 작업가스비의 변화에 관계없이(110)BST와 (111)BST 피크만이 관찰되었으며 작업가스 $Ar:O_2=80:20$에서 가장 양호한 결정성을 나타내었다. I-V 측정결과 인가전계 ${\pm}100kV/cm$에서 $10^{-7}A/cm^2$이하의 양호한 누설전류 특성을 보여주고 있으며 C-V 측정결과 작업가스 $Ar:O_2$의 비율 90:10, 80:20, 70:30에서의 비유전율은 각각 283, 305, 296으로서 작업가스비 80:20에서 제작된 박막의 특성이 가장 우수하였다. 작업가스비 80:20에서 제작된 박막의 SEM 측정결과 결정이 성장되었음을 확인할 수 있었고 그레인의 크기는 약 10nm였다.