• Transactions of Materials Processing
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• v.28 no.1
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• pp.43-48
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• 2019

Aluminum nitride (AlN) is used by the semiconductor industry, and is a compound that is required when manufacturing high thermal conductivity. The AlN films with c-axis orientation and thermal conductivity characteristic were deposited by using the Pulsed Laser Deposition (PLD). The AlN thin films were characterized by changing the deposition conditions. In particular, we have researched the AlN thin film deposited under optimal conditions for growth atmosphere. The epitaxial AlN films were grown on sapphire ($c-Al_2O_3$) single crystals by PLD with AlN target. The AlN films were deposited at a fixed temperature of $650^{\circ}C$, while conditions of nitrogen ($N_2$) pressure were varied between 0.1 mTorr and 10 mTorr. The quality of the AlN films was found to depend strongly on the $N_2$ partial pressure that was exerted during deposition. The X-ray diffraction studies revealed that the integrated intensity of the AlN (002) peak increases as a function the corresponding Full width at half maximum (FWHM) values decreases with lowering of the nitrogen partial pressure. We found that highly c-axis orientated AlN films can be deposited at a substrate temperature of $650^{\circ}C$ and a base pressure of $2{\times}10^{-7}Torr$ in the $N_2$ partial pressure of 0.1 mTorr. Also, it is noted that as the $N_2$ partial pressure decreased, the thermal conductivity increased.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.6
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• pp.575-579
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• 2008

Al-doped p-type ZnO films were fabricated on n-Si (100) and homo-buffer layers in pure oxygen at $450^{\circ}C$ of by RF magnetron sputtering. Target was ZnO ceramic mixed with 2 wt% $Al_2O_3$. XRD spectra show that the Al-doped ZnO thin films have ZnO crystal structure and homo-buffer layers are beneficial to Al-doped ZnO films to grow along c-axis. Hall Effect experiments with Van der Pauw configuration show that p-type carrier concentrations are ranged from $1.66{\times}10^{16}$ to $4.04{\times}10^{18}\;cm^{-3}$, mobilities from 0.194 to $2.3\;cm^2V^{-1}s^{-1}$ and resistivities from 7.97 to $18.4\;{\Omega}cm$. p-type sample has density of $5.40\;cm^{-3}$ which is smaller than theoretically calculated value of $5.67\;cm^{-3}$. XPS spectra show that Ols has O-O and Zn-O structures and Al2p has only Al-O structure. P-ZnO:Al/n-ZnO:Al junctions were fabricated by magnetron sputtering. V-I curves show that the p-n junctions have rectifying characteristics.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.168.1-168.1
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• 2015

자동차 산업분야에서 차량 경량화의 한 수단으로, 자동차용 유리를 무게가 가볍고 고강도 투명 고분자 소재인 폴리카보네이트로 대체하고자 하는 연구가 이루어지고 있다. 하지만, 폴리카보네이트의 낮은 내 마모 특성과 자외선에 의한 열화 및 변색 현상은 해결해야 할 문제점으로 지적되고 있다. 본 연구에서는, 폴리카보네이트의 내마모 특성을 향상시키기 위해 HIPIMS+ (High Power Impulse Magnetron Sputtering+) 방법을 이용하여 투과율이 확보되고, 고경도 특성을 갖는 Al-Si-N 박막을 증착하였다. 고속증착을 하기 위해 Target에 인가되는 Power를 올리게 되었는데, 열팽창 계수가 큰 고분자 물질인 폴리카보네이트 시료의 온도가 상승하여 증착된 박막과의 열팽창 계수 차이에 의해 박막에 Crack이 형성되는 문제가 발생하였다. 증착되는 Al-Si-N 박막의 공정 압력에 따른 Stress 제어 방법 및 폴리카보네이트 시료의 온도 상승을 막기 위한 알루미늄 구조체를 이용함으로써 박막의 Crack 형성을 억제하고자 하였다. 박막의 Stress를 확인하기 위하여 AFM (Atomic Force Microscope)과 OM (Optical Microscope)을 이용하여 분석하였고, 박막의 경도는 Knoop ${\mu}$-hardness tester를 사용하여 측정하였다. Al-Si-N 박막 경도는 Si at.%/(Al at.% + Si at.%) 비율이 16%에서 33 GPa의 경도를 갖는 것을 확인하였다. UV-Vis Spectrometer를 이용하여 투과율을 측정한 결과, 400-700 nm 파장의 가시광 영역 평균 투과율은 80%로 측정되었다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.303-304
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• 2008

Al, N-codoped ZnO(ZnO:N,Al) thin films were deposited on n-type Si(100) substrate at $450^{\circ}C$ with various conditions of ambient gas$(N_2:O_2)$ by DC magnetron sputtering method using ZnO:$Al_2O_3$(2wt%) as a target, and then were annealed at 500, 700, $800^{\circ}C$ in $N_2$ gas for one hour. XRD patterns showed that all of the ZnO:N,Al thin films annealed at $80^{\circ}C$ grew with two peaks, which means poor crystallinity of the thin films deposited. Hall effects in Van der Pauw configuration proved that after annealing the films deposited showed low resistivity and high carrier concentration. While the films annealed at $800^{\circ}C$ showed low resistivity of $\sim10^{-2}\Omega$ cm and high carrier concentration of $\sim10^{19}cm^{-3}$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11b
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• pp.525-528
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• 2001

ZnO:Al thin film can be used as a transparent conducting oxide(TCO) which has low electric resistivity and high optical transmittance for the front electrode of amorphous silicon solar cells and display devices. This study of electrical, crystallographic and optical properties of Al doped ZnO thin films prepared by Facing Targets Sputtering(FTS), where strong internal magnets were contained in target holders to confine the plasma between the targets, is described. Optimal transmittance and resistivity was obtained by controlling flow rate of $O_2$ gas and substrate temperature. When the $O_2$ gas rate of 0.3 and substrate temperature $200^{\circ}C$, ZnO:Al thin film had strongly oriented c-axis and lower resistivity( < $10^{-4}{\Omega}-cm$ ).

• Journal of the Korean Ceramic Society
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• v.43 no.9 s.292
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• pp.532-536
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• 2006

The annealing temperature effect of transparent conducting oxide film grown on glass substrate for solar cell application was studied in this paper. Using pulsed DC magnetron sputtering with 1 at% Al-doped ZnO target, TCO films were deposited on coming 7059 glass at room temperature. Al:ZnO thin films were annealed at 200, 400, Al $600^{\circ}C$ for 10 min and annealing resulted in lower biaxial compressive stress of about 1GPa and increased average crystallite size in all films. The as-grown film shows the resistivity of $1{\times}10^{-2}{\Omega}{\cdot}cm$ and transmittance under 80%, whereas the electrical and optical properties of film annealed at $400^{\circ}C$ are enhanced up to $5{\times}10^{-4}{\Omega}{\cdot}cm$ and 85%, respectively.

• Transactions on Electrical and Electronic Materials
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• v.9 no.2
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• pp.67-72
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• 2008

Al-doped p-type ZnO thin films were fabricated by RF magnetron sputtering on n-Si (100) and homo-buffer layers in pure oxygen ambient. ZnO ceramic mixed with 2 wt% $Al_2O_3$ was selected as a sputtering target. XRD spectra show that the Al-doped ZnO thin films have ZnO crystal structure. Hall Effect experiments with Van der Pauw configuration show that p-type carrier concentrations are arranged from $1.66{\times}10^{16}$ to $4.04{\times}10^{18}\;cm^{-2}$, mobilities from 0.194 to $198\;cm^2V{-1}s^{-1}$ and resistivities from 0.0963 to $18.4\;{\Omega}cm$. FESEM cross section images of different parts of a p-type ZnO:Al thin film annealed at $800^{\circ}C$ show a compact structure. Measurement for same sample shows that density is $5.40\;cm^{-3}$ which is smaller than theoretically calculated value of $5.67\;cm^{-3}$. Photoluminescence (PL) spectra at 10 K show a shoulder peak of p-type ZnO film at about 3.117 eV which is ascribed to electron transition from donor level to acceptor level (DAP).

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.460-463
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• 2000

The current-voltage characteristics of the sandwich system at different annealing temperatures and different bias voltages have been studied. In order to prepare the Al/V$O_X$/Al sandwich devices structure, thin films of vanadium oxide(V$O_X$) was deposited by r.f. magnetron sputtering from $V_2$$O_5$ target in 10% gas mixture of argon and oxygen, and annealed during lhour at different temperatures in vacuum. Crystall structure, surface morphology, and thickness of films were characterized through XRD, SEM and I-V characteristics were measured by electrometer. The films prepared below 20$0^{\circ}C$ were amorphous, and those prepared above 300 $^{\circ}C$were polycrystalline. At low fields electron injected to conduction band of vanadium oxide and formed space charge, current was limited by trap. Conduction mechanism at mid fields due to Schottky emission, while at high fields it changed to Fowler-Nordheim tunneling effects.

• Electrical & Electronic Materials
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• v.10 no.7
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• pp.706-712
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• 1997

AlN(Aluminium Nitride) thin films were prepared using by RF sputtering method on the Si(100) and Si(111) substrates as the parameters of the substrate temperature, RF power, sputtering duration and the $N_2$/Ar ratio and investigated by X-ray diffraction, IR spectrometry, n&k analyzer. For the Si(100) substrate, the AlN thin films of (101) orientation were obtained under the conditions of room temperature and the nitrogen of 60 vol.%. For the Si(111) substrate, the (002) AlN thin films were obtained under the nitrogen of 100 vol.%. In case of the thin film prepared in the condition of above 60 vol.% of the nitrogen, the average value of the surface roughness of the film was 151$\AA$. From the changes of the half widths of E$_1$[TO] phonon bands at the wavenumber of 680$cm^{-1}$ /, it were compared of the crystallinities of the films which were grown under the different conditions. The thicknesses of AlN films were decreased dramatically in the region of the nitrogen of 40~60 vol.%. Its due to the nitridation of the Al target surface and getting low of the sputtering yield by the $N_2$/Ar ratio being increased.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.74-75
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• 2007

We report on the characteristics of organic light-emitting diodes with Al cathode deposited by specially designed twin target sputter(TTS) system. It was found that the Al cathode films grown by TTS system were amorphous structure with nanocrystallines due to low substrate temperature during sputtering process. Effective confinement of high-density plasma between two Al targets lead to low temperature sputtering process on organic layer. Moreover, organic light-emitting diodes with Al cathode deposited by TTS system exhibited low leakage current density of $4{\times}10^{-6}\;mA/cm2$ at -6 V indicating plasma damage due to bombardment of energetic particles such as ions and $\gamma$-electrons was effectively restricted in the ITS system. Sputtering method using ITS system is expected to be applied in organic electronics and flexible displays due to its low temperature and plasma damage free deposition process.