• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.11
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• pp.2385-2390
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• 2009

N-doped ZnO thin films with c-axis preferred orientation were prepared on p-Si(100) wafers, using an RF magnetron sputter deposition. For ZnO deposition, $N_2O$ gas was employed as a dopant source and various deposition conditions such as $N_2O$ gas fraction and RF power were applied. The depth pofiles of the nitrogen [N] atoms incorporated into the ZnO thin films were investigated by Auger Electron Spectroscopy(AES) and the nano-scale structural characteristics of the N-doped ZnO thin films were also investigated by a scanning electron microscope (SEM) technique.

• Air Cleaning Technology
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• v.17 no.4 s.67
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• pp.39-57
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• 2004

첨단산업으로 불리는 반도체, LCD, PDP, 유기EL(OLED) 등의 생산 공정은 고도의 청정상태를 요구하며, 때문에 이들의 생산공정 중 대부분이 클린룸 내에서 이루어진다. 클린룸 내에서의 주요공정은 크게 박막형성(Layering), 노광(Photo Lithography), 식각(Etching) 등 3가지 공정으로 나눌 수 있으며, 반도체 제조공정의 경우 특별히 도핑(Doping) 공정이 추가된다. 오염물질을 함유하는 클린룸 배기는 일반적으로 산, 알칼리, Toxic(PFCs, Flammable), VOC 등으로 분류하며, 각각의 배기는 각 배기특성에 맞는 오염제어 장치를 통해, 정화된 후, 대기로 방출된다. 산, 알칼리 배기는 일반적으로 최종 단계에서 중앙집중식 습식스크러버에 의해 흡수, 중화 처리되며, VOC의 경우 농축기(Concentrator) & 축열식 열 산화장치(RTO) 설비에 의해 연소 처리된다. 하지만 CVD공정으로부터의 배기가 주를 이루는 Toxic배기의 경우, 다량의 PFCs(과불소화합물) 가스를 함유하고 있는 이유로, 대부분 클린룸 내부에 P.O.U(Point of use) 처리장치가 설치되며, P.O.U에 의해 1차 처리된 후 최종적으로 중앙집중식 습식스크러버를 거쳐 대기로 방출된다. 알칼리배기의 주성분으로는 암모니아($NH_3$), HMDS (Hexa Methyl DiSilazane), TMAH (Tetra Methyl Ammonium Hydroxide), LGL, CD 등이며 흡수액에 황산(Sulfuric Acid)용액을 공급, 중화처리하고 있다. 탄소성분을 먹이로 하는 미생물의 번식에 의한 막힘 문제를 제외하고는 큰 문제가 없다. 하지만 Toxic배기 및 산배기의 경우 처리효율이, 가스흡수 이론에 의한 계산결과와 비교할 때, 매우 저조하게 나타나는 효율부족 현상을 겪고 있으며, 이는 잔여 PFCs 가스성분 및 반응에어로졸, 응축에어로졸 등의 영향으로 추정하고 있다. 최근 Toxic 배기의 경우, P.O.U 설비를 Burn & Wet type으로 변경하여, 배기 중 PFCs 및 반응에 에어로졸($SiO_2$)의 농도를 원천적으로 감소시키는 노력이 진행 중이다. 산배기의 경우, 산결로 현상에 의한, 응축에어로졸이 문제가 되고 있으나 내식열교환기(Anti-Corrosive Heat Exchanger), 하전액적스크러버 시스템(Charged Droplets Scrubber System), Wet ESP(Wet Electrostatic Procipitator) 등의 도입을 통해 문제해결을 위한 노력을 경주하고 있다.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.193.1-193.1
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• 2014

This study was to investigate the electronic structure and optical properties of Na doped into NiO thin film using XPS and REELS. The films were grown by electron beam evaporation with varying the annealing temperature. The relationship between the electrical characteristics with the local structure of NiO thin films was also discussed. The x-ray photoelectron results showed that the Ni 2p spectra for all films consist of Ni 2p3/2 which indicate the presence of Ni-O bond from NiO phase and for the annealed film at temperature above $200^{\circ}C$ shows the coexist Ni oxide and Ni metal phase. The reflection electron energy loss spectroscopy spectra showed that the band gaps of the NiO thin films were slightly decreased with Na-doped into films. The Na-doped NiO showed relatively low resistivity compared to the undoped NiO thin films. In addition, the Na-doped NiO thin films deposited at room temperature showed the best properties, such as a p-type semiconducting with low electrical resistivity of $11.57{\Omega}.cm$ and high optical transmittance of ~80% in the visible light region. These results indicate that the Na doping followed by annealing process plays a crucial in enhancing the electrical and optical properties of NiO thin films. We believe that our results can be a good guide for those growing NiO thin films with the purpose of device applications, which require deposited at room temperature.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.1
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• pp.77-81
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• 2015

Background: The aim of the study was to determine whether the expression of baseline phosphorus (P) and magnesium (Mg) levels were prognostic in terms of stage and overall survival (OS) in newly diagnosed non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC) patients. Materials and Methods: Retrospectively, 130 patients were selected at the time of diagnosis oflung cancer (100 with NSCLC and 30 with SCLC), before the initialization of any chemo-radiotherapy. The median age was 67 (range 29-92). IA, IB, IIA, IIB, IIIA, IIIB and IV stages were present in 3, 4, 19, 6, 25, 8, and 65 patients, respectively. After centrifugation, the levels of serum P and Mg were measured using the nephelometric method/ photometry and evaluated before any type of treatment. Results: Higher than normal levels of P were found in 127/130 patients, while only four patients had elevated Mg serum values. In terms of Spearman test, higher P serum values correlated with either stage (rho=- 0.334, p<0.001) or OS (rho=-0.212, p=0.016). Additionally, a significant negative correlation of Mg serum levels was found with stage of disease (rho=-0.135, P=0.042). On multivariate cox-regression survival analysis, only stage (p<0.01), performance status (p<0.01) and P serum (p=0.045) showed a significant prognostic value. Conclusions: Our study indicated that pre-treatment P serum levels in lung cancer patients are higher than the normal range. Moreover, P and Mg serum levels are predictive of stage of disease. Along with stage and performance status, the P serum levels had also a significant impact on survival. This information may be important for stratifying patients to specific treatment protocols or intensifying their therapies. However, larger series are now needed to confirm our results.

• Journal of the Korean Chemical Society
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• v.60 no.6
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• pp.402-409
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• 2016

Thin films of lead sulfide colloidal quantum dots (CQDs) of 2.8 nm in diameter are fabricated and their surfaces are passivated by 3-mercaptopropionic acid (MPA) ligand or hybrid type ($MPA+CdCl_2$) ligand, respectively. The changes in valence band electronic structure and atomic composition of each PbS CQD film upon post-treatment such as air, N2 annealing or UV/Ozone have been studied by photoelectron spectroscopy. The air annealing makes the CQD fermi level to move toward the valence band leading to "p-type doping" regardless of ligand type. The UV/Ozone post-treatment generates $Pb(OH)_2$, $PbSO_x$ and PbO on both CQD surfaces. But the amount of the PbO has been reduced in hybrid type ligand case, especially. That is probably because the extra Pb cations in (111) surface are additionally passivated by $Cl_2$ ligand, which limits the reaction between the Pb cation and ozone.

• Journal of the Korean Chemical Society
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• v.21 no.5
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• pp.320-329
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• 1977

p-Phenylenediamine dihydroperchlorate, $C_6H_4N_2H_4{\cdot}2HC1O_4$, crystallizes in space group $P\={1}$ with $a=4.79{\pm}0.02,\;b=9.03{\pm}0.02,\;c=7.12{\pm}0.03{\AA},\;{\alpha}=109.4{\pm}0.2,\;{\beta}=79.6{\pm}0.2,\;r=104.6{\pm}0.2^{\circ},\;Z=1$. The structure has been solved by the Patterson and Fourier methods. The refinement by block-diagonal least-squares cycles gives R = 0.13 for 387 observed reflexions collected on equi-inclination Weissenberg photographs with CuK${\alpha}$ radiation. There are two different types of five hydrogen bonds. The first type consists of one trifurcated N${\cdot}{\cdot}{\cdot}$O hydrogen bond and the second of two normal N${\cdot}{\cdot}{\cdot}$O hydrogen bonds, both of which exist between the amino group and the perchlorate, groups. A p-phenylenediamine group is approximately planar within an experimental error and bonded to twelve perchlorates: ten perchlorates forming hydrogen bonds and two being contacted with the van der Waals forces. A perchlorate group is surrounded by six p-phenylenediamines and four perchlorates; among the six p-phenylenediamines, five of them are hydrogen-bonded, and the rest contacted with the van der Waals force.ce anaysis of our samples and investigated the variarions in the values of parameters obtained through fitting the theoretical impedance to the experimental impedance. The characters of the dielectric constant and the impedance showed abnormal variations for the 0.2 at K-doped NSBN ceramics, which we were able to interpret in terms of the variations in the number A-site vacancies with the K doping ratio. From these results, A-site vacancies are thought to be space charges that influence the ferroelectric properties of NSBN ceramics.

• Korean Journal of Crystallography
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• v.7 no.1
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• pp.73-80
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• 1996

The single crystal growth has been carried out with the newly designed 1-T HB(single temperature zone horizontal Bridgman) system for GaAs crystals of 2 inch diameter doped with Si, Zn or undoped. With this method, incidence probability of single crystallinity was shown to be 0.73. Lattice defects evaluated from EPD(etch pit density) measurement were in the range of 5,000-20,000/cm2, dependent upon the doping condition. For the undoped GaAs crystals, carrier concentrations from the Hall measurement were ∼1×1016/cm3 at the seed part, which were less than half the concentrations of double of triple temperature zone(2-T, 3-T) HB grown crystals. By the 1-T HB method, therefore, GaAs crystals can be grown successfully with better yield and higher purity.

• Advances in nano research
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• v.10 no.5
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• pp.415-422
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• 2021

Silicene, a 2D allotrope of silicon, is predicted to be a potential material for future transistor that might be compatible with present silicon fabrication technology. Similar to graphene, silicene exhibits the honeycomb lattice structure. Consequently, silicene is a semimetallic material, preventing its application as a field-effect transistor. Therefore, this work proposes the uniform doping bandgap engineering technique to obtain the n-type silicene nanosheet. By applying nearest neighbour tight-binding approach and parabolic band assumption, the analytical modelling equations for band structure, density of states, electrons and holes concentrations, intrinsic electrons velocity, and ideal ballistic current transport characteristics are computed. All simulations are done by using MATLAB. The results show that a bandgap of 0.66 eV has been induced in uniformly doped silicene with phosphorus (PSi₃NW) in the zigzag direction. Moreover, the relationships between intrinsic velocity to different temperatures and carrier concentration are further studied in this paper. The results show that the ballistic carrier velocity of PSi₃NW is independent on temperature within the degenerate regime. In addition, an ideal room temperature subthreshold swing of 60 mV/dec is extracted from ballistic current-voltage transfer characteristics. In conclusion, the PSi₃NW is a potential nanomaterial for future electronics applications, particularly in the digital switching applications.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.9 no.6
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• pp.574-579
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• 1999

A counter-flow type horizontal reactor of metal organic chemical vapor deposition was designed with the Reynolds and the Rayleigh numbers of Re = 4.5 and Ra = 215.8, respectively. The GaN thin films were grown and characterized by Hall measurement, double crystal X-ray diffraction analysis and photoluminescence measurement. The Si and Mg were also used for doping of GaN films. The dislocation density of $2.6{\times}10^8/\textrm {cm}^2$ was included in GaN films representing the geometrical lattice mismatch between sapphire substrates and GaN films. The Si doped n-GaN films provide the electron carrier density and mobility in the regions of $10^{17}~10^{18}/\textrm{cm}^3$ and 200~400 $\textrm{cm}^2$/V .sec, respectively. Mg doped p-GaN films were post-annealed and activated with the hole carrier density of $8{\times}10^{17}/{\textrm}{cm}^3$.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.193.2-193.2
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• 2015

최근 3차원 반도체의 물질적인 한계를 극복하기 위해 2차원 전이금속 칼코게나이드(TMD)에 대한 연구가 활발히 진행되고 있다. 하지만 TMD 물질의 도핑 방법에 대한 수많은 연구에도 불구하고 대부분이 n채널 물질인 MoS2에 대한 것에 국한되어 있다. 게다가 이전의 TMD 도핑 기술 연구 결과는 채널이 도체화 될 정도의 매우 높은 농도의 도핑 현상만을 보여주었다. 이 연구에서 우리는 WSe2로 만든 p형 채널 트랜지스터에서 Octaecyltrichlorosilane(OTS)층의 농도 조절로 제어가 가능한 약한 농도의 p형 도핑기술을 보여준다. 이 p형 도핑 현상은 OTS의 메틸기(-CH3)그룹에 의한 양성 쌍극자모멘트가 WSe2내의 전자 농도를 낮추는데서 기인한다. 제어가 가능한 p형 도핑은 $2.1{\times}10^{11}cm^{-2}$ 사이에서 $5.2{\times}10^{11}cm^{-2}$로 degenerate되지 않은 정도로 WSe2 기반의 광, 전기적인 소자에서 적절한 농도로 최적화 될 수 있다. (도핑 정도에 따른 문턱전압 상승, 전류 on/off율 상승, 전계효과 이동도 상승, 광응답성 하락, 광검출성 하락) 또한 OTS에서 비롯한 p도핑 효과는 대기중에서 오랜시간이 지나도 작은 성능 변화만을 보여주며(60시간 후 18~34% 문턱전압 감소변화량) $120^{\circ}C$의 열처리를 통하여 저하된 성능이 거의 완벽하게 회복된다. 이 연구는 Raman 분광법과 전기적, 광학적 측정을 통하여 분석되었으며 OTS 도핑현상이 WSe2 박막의 두께와 무관함 또한 확인했다.