• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.12S
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• pp.1224-1231
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• 2003

This paper reports on the air-gap type thin film bulk acoustic wave resonator(FBAR) using ultra thin wafer with thickness of 50$\mu\textrm{m}$. It was fabricated to realize a small size devices and integrated objects using MEMS technology for flexible microsystems. To reduce a error of experiment, MATLAB simulation was executed using material characteristic coefficient. Fabricated thin FBAR consisted of piezoelectric film sandwiched between metal electrodes. Used piezoelectric film was the aluminum nitride(AlN) and electrode was the molybdenum(Mo). Thin wafer was fabricated by wet etching and dry etching, and then handling wafer was used to prevent damage of FBAR. The series resonance frequency and the parallel frequency measured were 2.447㎓ and 2.487㎓, respectively. Active area is 100${\times}$100$\mu\textrm{m}$$^2$.Q-factor was 996.68 and K$^2$$\_$eff/ was 3.91％.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.55 no.1
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• pp.26-29
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• 2006

Transparent ZnO thin films were prepared by KrF pulsed laser deposition (PLD) technique and applied to a bottom-gate type thin film transistor device as an active channel layer. A high conductive crystalline Si substrate was used as an metal-like bottom gate and SiN insulating layer was then deposited by LPCVD(low pressure chemical vapour deposition). An aluminum layer was then vacuum evaporated and patterned to form a source/drain metal contact. Oxygen partial pressure and substrate temperature were varied during the ZnO PLD deposition process and their influence on the thin film properties were investigated by X-ray diffraction(XRD) and Hall-van der Pauw method. Optical transparency of the ZnO thin film was analyzed by UV-visible phometer. The resulting ZnO-TFT devices showed an on-off ration of $10^6$ and field effect mobility of 2.4-6.1 $cm^2/V{\cdot}s$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.04a
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• pp.65-66
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• 2008

The realization and origin of p-type ZnO are main issue for photoelectronic devices based on ZnO material. N-doped and nominally undoped p-type ZnO films were achieved on silicon (100) and homo-buffer layers by RF magnetron sputtering and post in-situ annealing. The undoped film shows high hole mobility of 1201 $cm^2V^{-1}s^{-1}$ and low resistivity of $0.0454\Omega{\cdot}cm$ with hole concentration of $1.145\times10^{17}cm^{-3}$. The photoluminescence(PL) spectra show the emissions related to FE, DAP and defects of $V_{Zn}$, $V_O$, $Zn_O$, $O_i$ and $O_{Zn}$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.05b
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• pp.21-24
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• 2000

Properties of thermoelectric power in PbS thin films by chemical bath deposition were investigated The qualified PbS thin film was gained with the amounts of Thiourea($4-8ml/{\ell}$ ), Triethanolamine (1-2ml) and NaOH(l0ml). The molecular ratio of Pb and S was 3 : 7. Satisfied crystallization rate and deposition rate of PbS were greater at $50^{\circ}C$ than at $30^{\circ}C$. The constant of thermoelectric power in PbS was nearly $ 500uv/^{\circ}k$. The PbS thin film was changed from p-type to n-type semiconductor at around $200^{\circ}C$. In case of heat treatment at $300^{\circ}C$, the sample kept the characteristic of p-type semiconductors up to $250^{\circ}C$.

• Journal of Sensor Science and Technology
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• v.15 no.2
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• pp.84-89
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• 2006

Highly concentrated p-type ZnO thin films can be obtained by doping of N, P and As elements. In this study, undoped ZnO buffer layers were prepared on a (0001) sapphire substrate by a ultra high vaccum pulsed laser deposition(UHV-PLD) method. ZnO buffer layers were deposited with various deposition temperature($400{\sim}700^{\circ}C$) at 350 mtorr of oxygen working pressure. Arsenic doped(1 wt%) ZnO thin films were deposited on the ZnO buffer layers by UHV-PLD. Crystallinity of the samples were evaluated by X-ray diffractometer and scanning electron microscopy. Optical, electrical properties of the ZnO thin films were estimated by photoluminescence(PL) and Hall measurements. The optimal condition of the undoped ZnO buffer layer for the deposition of As-doped ZnO thin films was at $600^{\circ}C$ of deposition temperature.

• Proceedings of the KIEE Conference
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• 2006.10a
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• pp.53-54
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• 2006

Arsenic doped p-type ZnO thin films have been realized on intrinsic (100) GaAs substrate by RF magnetron sputtering and thermal annealing treatment. p-Type ZnO exhibits the hole concentration of $9.684{\times}10^{19}cm^3$, resistivity of $2.54{\times}10^{-3}{\Omega}cm$, and mobility of $25.37\;cm^2/Vs$. Photoluminescence (PL) spectra of As doped p-type ZnO thin films reveal neutral acceptor bound exciton ($A^{0}X$) of 3.3437 eV and a transition between free electrons and acceptor levels (FA) of 3.2924 eV. Calculated acceptor binding energy ($E_A$) is about 0.1455 eV. Thermal activation and doping mechanism of this film have been suggested by using X-ray photoelectron spectroscopy (XPS). p-Type formation mechanism of As doped ZnO thin film is more related to the complex model, namely, $As_{Zn}-2V_{Zn}$, in which the As substitutes on the Zn site, rather than simple model, Aso, in which the As substitutes on the O site. ZnO-based p-n junction was fabricated by the deposition of an undoped n-type ZnO layer on an As doped p-type ZnO layer.

• Korean Journal of Materials Research
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• v.30 no.4
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• pp.169-175
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• 2020

Silicon nitride thin films are deposited by RF (13.57 MHz) magnetron sputtering process using a Si (99.999 %) target and with different ratios of Ar/N₂ sputtering gas mixture. Corning G type glass is used as substrate. The vacuum atmosphere, RF source power, deposit time and temperature of substrate of the sputtering process are maintained consistently at 2 ~ 3 × 10^-3 torr, 30 sccm, 100 watt, 20 min. and room temperature, respectively. Cross sectional views and surface morphology of the deposited thin films are observed by field emission scanning electron microscope, atomic force microscope and X-ray photoelectron spectroscopy. The hardness values are determined by nano-indentation measurement. The thickness of the deposited films is approximately within the range of 88 nm ~ 200 nm. As the amount of N₂ gas in the Ar:N₂ gas mixture increases, the thickness of the films decreases. AFM observation reveals that film deposited at high Ar:N₂ gas ratio and large amount of N₂ gas has a very irregular surface morphology, even though it has a low RMS value. The hardness value of the deposited films made with ratio of Ar:N₂=9:1 display the highest value. The XPS spectrum indicates that the deposited film is assigned to non-stoichiometric silicon nitride and the transmittance of the glass with deposited SiO₂-Si_xN_y thin film is satisfactory at 97 %.

• Journal of the Semiconductor & Display Technology
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• v.9 no.1
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• pp.29-33
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• 2010

Recently, the growth of ZnO thin film on glass substrate has been investigated extensively for transparent thin film transistor. We have studied the phase transition of ZnO thin films from metal to semiconductor by changing RF power in the deposition process by RF magnetron sputtering system. The structural, electric, and optical properties of the ZnO thin films were investigated. The film deposited with 75 watt of RF power showed n-type semiconductor characteristic having suitable resistivity $-3.56\;{\times}\;10^{+1}\;{\Omega}cm$, carrier concentration $-2.8\;{\times}\;10^{17}\;cm^{-3}$, and mobility $-0.613\;cm^2V^{-1}s^{-1}$ while other films by 25, 50, 100 watt of RF power closed to metallic films. From the surface analysis (AFM), the number of crystal grain of ZnO thin film increased as RF power increased. The transmittance of the film was over 88% in the visible region regardless of the change in RF power.

• Korean Journal of Materials Research
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• v.27 no.2
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• pp.89-93
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• 2017

A thin film thermoelectric generator that consisted of 5 p/n pairs was fabricated with $1{\mu}m$-thick n-type $In_3Sb_1Te_2$ and p-type $Ge_2Sb_2Te_5$ deposited via radio frequency magnetron sputtering. First, $1{\mu}m$-thick GST and IST thin films were deposited at $250^{\circ}C$ and room temperature, respectively, via radio-frequency sputtering; these films were annealed from 250 to $450^{\circ}C$ via rapid thermal annealing. The optimal power factor was found at an annealing temperature of $400^{\circ}C$ for 10 min. To demonstrate thermoelectric generation, we measured the output voltage and estimated the maximum power of the n-IST/p-GST generator by imposing a temperature difference between the hot and cold junctions. The maximum output voltage and the estimated maximum power of the $1{\mu}m$-thick n-IST/p-GST TE generators are approximately 17.1 mV and 5.1 nW at ${\Delta}T=12K$, respectively.

• Proceedings of the Korean Ceranic Society Conference
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• 1986.12a
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• pp.287-304
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• 1986

High quality monocrystalline $\beta$-SiC thin films were grown via two-step process of conversion of the Si(100) surface by reaction with $C_2H_4$ and the subsequent chemical vapor deposition (CVD) at $1360^{\circ}C$ and 1 atm total pressure. Four dopants, B and Al and p-type, and N and P for n-type, were also incorporated into monocrystalline $\beta$-SiC thin films during the CVD growth process. IR and Raman spectroscopies were used to evaluate the quality of the undoped $\beta$-SiC thin films and to investigate the effects of dopants on the structure of the doped $\beta$-SiC thin films. The changes in the shape of IR and Raman spectra of the doped thin films due to dopants were observed. But the XTEM micrographs except for the B-doped and annealed films showed the same density and distribution of stacking faults and dislocations as was seen in the undoped samples, The IR and Raman spectra of the B-doped and annealed films showed the broad and weak bands and one extra peak at the 850 $cm^{-1}$ respectively. The SAD pattern and XTEM micrograph of the B-doped and annealed film provided the evidence for twinning.