• Proceeding of EDISON Challenge
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• 제6회(2017년)
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• pp.404-411
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• 2017

이 논문에서는 2차원 화합물 반도체인 Indium Selenide monolayer의 효과적인 도펀트 원소를 탐색해보았다. 총 4가지 종류의 원소를 도핑시켜 계산을 했다. In 자리에 Mg과 Sn을 도핑시켜 각각 p-type과 n-type으로 만들고 Se 자리에 As과 Br을 도핑시켜 각각 p-type과 n-type으로 만들었다. 변화한 성질을 알아보기 위해 전자 구조를 분석하고 band structure와 DOS를 살펴보았다. P-type 같은 경우, Mg doped InSe는 shallow defect level이 생겨 좋은 반도체로 쓰일 수 있지만 As을 도핑한 InSe는 deep defect states가 생겼다. VBM에서 약 0.67 eV만큼 떨어져있는데 이 수치는 실험값과 비슷한 값이다. N-type 경우에는 Sn doped InSe는 deep defect states가 생겼고, CBM 아래로 약 0.08eV만큼 defect가 생긴 것이 실험값과 비슷하다. Br doped InSe는 Sn doped InSe보다 안정적인 n형 반도체가 될 수 있다.

• Journal of the Korean Crystal Growth and Crystal Technology
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• 제17권2호
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• pp.47-51
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• 2007

F-doped SiOC : H thin films with low refractive index were deposited on Si wafer and glass substrate by plasma enhanced chemical vapor deposition (PECVD) as a function of rf powers, substrate temperatures, gas rates and their composition flow ratios ($SiH_4,\;CF_4$ and $N_2O$). The refractive index of the F-doped SiOC : H film continuously decreased with increasing deposition temperature and rf power. As $N_2O$ gas flow rate decreased, the refractive index of the deposited films decreased down to 1.3778, reaching a minimum value at rf power of 180W and $100^{\circ}C$ without $N_2O$ gas. The fluorine content of F-doped SiOC : H film increased from 1.9 at% to 2.4 at% as the rf power was increased from 60 W to 180 W, which results in the decrease of refractive index.

• Journal of the Korean Society for Heat Treatment
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• 제33권1호
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• pp.13-19
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• 2020

Annealing effects on the properties of Bi-doped ZnO thin films were investigated. Bi- doped ZnO thin films were deposited on quartzs substrates at 300℃ by using radio-frequency magnetron sputtering system. Post heat treatments at 600, 700, and 800℃ were performed to evaluate the effect of annealing temperatures on the structural, optical, and electrical properties of Bi-doped ZnO thin films. FE-SEM images showed the dramatic surface morphology changes by rearrangement of elements at high heat treatment temperature of 800℃. X-ray diffraction analysis indicated that the peaks of the Bi-doped ZnO thin films were same as the peaks of the (002) planes of ZnO peak-positioned at 2θ=34.0° and peak intensities and FWHMs were improved as the annealing temperatures increased. The optical transmittance was improved with increasing annealing temperatures and was over 80% in the wavelength region between 435 and 1100 nm at the annealing temperature of 700 and 800℃. With increasing annealing temperature, the electron concentrations and electron mobilities were increased. On the other hand, electric resistivity of the films were decreased with increasing annealing temperatures. These results showed that the heat treatment temperature is an important parameter to improve the structural, optical, and electrical properties of Bi-doped ZnO thin films.

• Proceedings of the Korean Vacuum Society Conference
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• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
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• pp.142.2-142.2
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• 2013

The effect of substrate on catalytic activity of CO oxidation with transition metal Platinum nanoparticles on doped and undoped TiO2 was investigated. Titanium dioxide was doped chemically with non-metal anions including nitrogen and fluorine. Undoped TiO2 was synthesized via simple conventional sol-gel route. Thin films of titania were developed by spin coating technique and the characterization techniques SEM, XRD, UV-Vis Absorption Spectroscopy and XPS were carried out to examine the morphology of films, crystal phase, crystallites, optical properties and elemental composition respectively. XPS analysis from doped TiO2 confirmed that the nitrogen site were interstitial whereas fluorine was doped into TiO2 lattice substitutionally. Catalytic activity systems of Pt/doped-TiO2 and Pt/undoped-TiO2 were fabricated to reveal the strong metal-support interaction effect during catalytic activity of CO oxidation reactions. By arc plasma deposition technique, platinum nanoparticles with mean size of 2.7 nm were deposited on the thin films of doped and undoped titanium dioxide. The CO oxidation was performed with 40 Torr CO and 100 Torr O2 with 620 Torr He carrier gas. Turn over frequency was observed two to three folds enhancement in case of Pt/doped TiO2 as compared to Pt/TiO2. The electronic excitation and the oxygen vacancies that were formed with the doping process were the plausible reasons for the enhancement of catalytic activity.

• Advances in nano research
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• 제5권1호
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• pp.13-25
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• 2017

We examine the total optical dielectric function (TODF) of impurity doped GaAs quantum dot (QD) from the viewpoint of anisotropy, position-dependent effective mass (PDEM) and position dependent dielectric screening function (PDDSF), both in presence and absence of noise. The dopant impurity potential is Gaussian in nature and noise employed is Gaussian white noise that has been applied to the doped system via two different modes; additive and multiplicative. A change from fixed effective mass and fixed dielectric constant to those which depend on the dopant coordinate manifestly affects TODF. Presence of noise and also its mode of application bring about more rich subtlety in the observed TODF profiles. The findings indicate promising scope of harnessing the TODF of doped QD systems through expedient control of site of dopant incorporation and application of noise in desired mode.

• Bulletin of the Korean Chemical Society
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• 제23권10호
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• pp.1404-1408
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• 2002

The resonance Raman spectra of trans-polyacetylene films doped heavily with electron donor (Na) and acceptor (HClO4) have been measured with excitation wavelengths between 488- and 1320-nm, and the relationships between the Raman excitation photon energies (2.54-0.94 eV) and its wavenumbers were discussed. We found the linear dependence of the Raman shifts with the exchanges of excitation photon energies. In particular, the Raman wavenumbers in the C=C stretching $(V_1$ band) showed a dramatic decrease with the increase in Raman excitation photon energies. In the case of acceptor doping, its change is larger than that of donor doping. The observed wavenumber (1255-1267 $cm^{-1}$) of the $V_2$ band (CC stretch) of Na-doped form is lower than that of the corresponding band (1290-1292 $cm^{-1}$) of its pristine trans-polyacetylene, whereas the contrary is the case for the HClO4 doped form (1295-1300 $cm^{-1}$). The origin of doping-induced Raman bands is discussed in terms of negative and positive polarons.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• 제11권9호
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• pp.705-710
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• 1998

Intrinsic gettering is usually to improve wafer quality, which is an important factor for reliable ULSI devices. In order to generate oxygen precipitation in lightly and heavily boron doped silicon wafers with or without high $^75 As^+$ ion implantation, the 2-step annealing method was adopted. After annealing, the were cleaved and etched with th Wright etchant. The morphology of cross section on samples was inspected by FESEM(field emission scanning electron microscopy). The morphology of unimplanted samples was rater rough than that of the implanted. Oxygen precipitation density observed by an optical microscope in lightly boron doped samples was about 3$\times10^6/cm^3$. However, in heavily boron doped samples, the density of oxygen precipitation was largest at $600^{\circ}C$ in 1st annealing, and decreased abruptly until $800^{\circ}C$, But it increased slightly at $1000^{\circ}C$ and was independent with the implantation.

• Korean Chemical Engineering Research
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• 제49권3호
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• pp.357-360
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• 2011

N-doped ZnO nanofilms were prepared by plasma enhanced atomic layer deposition method. $Zn(C_{2}H_{5})_{2}$, $O_{2}$ and $N_{2}$ were used as Zn, O and N sources, respectively, for N-doped ZnO films under variation of radio frequency (rf) power from 50-300W. Structural, optical and electrical properties of as-grown ZnO films were investigated with Xray diffraction(XRD), photoluminescence(PL) and Hall-effect measurements, respectively. Nitrogen content and p-type conductivity in ZnO nanofilms increased with the rf power.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 한국전기전자재료학회 1997년도 춘계학술대회 논문집
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• pp.99-102
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• 1997

An electronic nose system is an instrument designed far mimicking human olfactory system. It consists generally of gas (odor) sensor array corresponding to olfactory receptors of human nose and artificial neural network pattern recognition technique based on human biological odor sensing mechanism. Considerable attempts to develop the electronic nose system have been made far applications in the fields of floods, drinks, cosmetics, environment monitoring, etc. A portable electronic nose system has been fabricated by using oxide semiconductor gas sensor array and pattern recognition technique such as principal component analysis (PCA) and back propagation artificial neural network The sensor array consists of six thick film gas sensors whose sensing layers are Pd-doped WO$_3$ Pt-doped SnO$_2$ TiO$_2$-Sb$_2$O$_3$-Pd-doped SnO$_2$ TiO$_2$-Sb$_2$O$_{5}$-Pd-doped SnO$_2$+Pd filter layer, A1$_2$O$_3$-doped ZnO and PdCl$_2$-doped SnO$_2$. As an application the system has been used to identify CO/HC car exhausting gases and the identification has been successfully demonstrated.d.

• Journal of Industrial Technology
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• 제31권B호
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• pp.119-125
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• 2011

N-doped Titanium oxides were prepared by using urea as a source of nitrogen. The photoactivities of the doped $TiO_2$ were evaluated on the basis of degradation of humic acid in aqueous solutions with different light sources, ultraviolet lamp, fluorescent lamp and solar light. XRD analysis was conducted to identify the crystal structure of the synthesized photocatalysts. N-doped $TiO_2$ and $pure-TiO_2$ was anatase type. SEM results showed that spherical particles were formed, which are the characteristics of the anatase form. N doped $TiO_2$ showed higher $UV_{254}$ decrease ratio and DOC removal ratio compared to $pure-TiO_2$. The humic acid degradation reaction using the UV-A lamp and UV-C lamp was assigned to pseudo-first order reaction. For solar light, only $pure-TiO_2$ and $N-TiO_2$ exhibited the pseudo-first order reaction.