• Applied Science and Convergence Technology
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• 제25권2호
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• pp.28-31
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• 2016

The structural and the electronic properties of pentacene on modified Si (001) were investigated using scanning tunneling microscopy (STM), atomic force microscopy (AFM) and ultraviolet photoelectron spectroscopy (UPS). Dodecane was used to modify Si (001) substrates and then pentacene was deposited on dodecane/Si (001). Our STM results show a uniform distribution of aggregated dodecane molecules all over the clean Si (001). The surface structure of pentacene on dodecaene/Si (001) examined by AFM is analogous to that of pentacene on $SiO_2$. The UPS data showed that the work function of pentacene on clean Si (001) and pentacene on modified Si (001) with dodecane was 6.41 and 5.57 eV, respectively. Our results prove that dodecane results in the work function difference between pentacene on clean Si (001) and pentacene on dodecane/Si (001).

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 C
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• pp.1513-1515
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• 1997

In this paper, we have investigated the characteristics of electrical conduction and photoconduction in LDPE. The electrical conduction characteristics of LDPE have been investigated at electric fields of 50 to 500 kV/cm and at temperatures of 25, $50^{\circ}C$. The photoconduction in LDPE induced by vacuum ultraviolet light irradiation have been investigated at electric fields 100, 200 kV/cm and at temperatures of 25, $50^{\circ}C$.

• Journal of the Optical Society of Korea
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• 제10권4호
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• pp.157-161
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• 2006

A synchrotron light source is useful in the vacuum ultraviolet (VUV) regime for olecular spectroscopy, such as photo absorption, photoionization, and dissociative hotoionization. In this research, we used a double-ion chamber (DIC) to measure hotoabsorption cross sections of a NO molecule in the wavelength range from 90 to 135 nm of 3B1 beam-line of the Pohang synchrotron light source with the resolution of the onochromator being 0.06 nm. The appearance wavelength for ionization was measured to be $134.19{\pm}0.09nm$ that is placed in the middle of the reported values though they don't agree with each other within the relative error limits. The auxiliary experimental works ave been done to test if there are any systematic error sources. The resultant ross-sections agree with previous results in general.

• 한국결정학회:학술대회논문집
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• 한국결정학회 2003년도 춘계학술연구발표회
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• pp.6-6
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• 2003

Highly crystalline 5H-polytypic form of sp3-bonded boron nitride (BN) was grown by pulsed-laser-vaporization of BN, where synchronous reactive-plasma packets assisted the crystal growth in the vapor phase. The structure of the product crystallites (˙5 micrometers) was confirmed by using transmission electron diffraction and electron energy loss spectroscopy. This material proved to have a sharp and dominant band at 225 nm by cathode luminescence at room temperatures and corresponding monochromatic images revealed that they uniformly emitted the ultraviolet light. Considering that cubic BN has already been doped as p- and n- type semiconductors, this material may be applied to the light-emitting devices working at almost the deepest limit of the UV region that is functional without vacuum.

• Applied Science and Convergence Technology
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• 제25권6호
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• pp.128-132
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• 2016

We investigated the effect of Ar ion sputtering on the surface electronic structure of indium tin oxide (ITO) using X-ray and ultraviolet photoelectron spectroscopy (XPS and UPS) measurements with increasing Ar ion sputtering time. XPS measurements revealed that surface contamination on ITO was rapidly removed by Ar ion sputtering for 10 s. UPS measurements showed that the work function of ITO increased by 0.2 eV after Ar ion sputtering for 10 s. This increase in work function was attributed to the removal of surface contamination, which formed a positive interface dipole relative to the ITO substrate. However, further Ar ion sputtering did not change the work function of ITO although the surface stoichiometry of ITO did change. Therefore, removing the surface contamination is critical for increasing the work function of ITO, and Ar ion sputtering for a short time (about 10 s) can efficiently remove surface contamination.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
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• pp.272-275
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• 2009

A new green phosphor, ($Mg_{1-x-yZnx)$)$Al_2O_4:Mn^{2+}{_y}$ (0 x 0.6, 0.001 y 0.01), was synthesized by a flux-assisted solid reaction and its vacuum ultraviolet (VUV) excitation and emission characteristics were examined in this study. The chromaticity and peak intensity of the $(Mg_{0.79}Zn_{0.2})Al_2O_4:Mn^{2+}{_{0.01}}$ (x = 0.177, y = 0.745) phosphor were found to be more desirable than that of $Zn_2SiO_4:Mn^{2+}$ (x = 0.216, y = 0.72) phosphor as a green primary color.

• Applied Science and Convergence Technology
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• 제23권5호
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• pp.301-307
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• 2014

We have fabricated $SnO_2$/Zn core-shell nanowires by employing a sputtering technique with a Zn target. Scanning electron microscopy indicated that the surface of the nanowires became rougher by the coating. X-ray diffraction of the coated nanowires exhibited the hexagonal Zn diffraction peaks. TEM image of coated structures showed that shell layer was mainly comprised of hexagonal Zn phase. EDX spectra suggested that the shell layer consisted of Zn elements. The photoluminescence spectrum of the coated nanowires in conjunction with Gaussian fitting analysis revealed that the emission was disconvoluted with three Gaussian functions, which are centered at 2.1 eV in the yellow region, 2.4 eV in the green region, and 3.3 eV in the ultraviolet region. We speculated the possible mechanisms of these emission peaks.

• Applied Science and Convergence Technology
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• 제26권2호
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• pp.30-33
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• 2017

ZnO thin films which were deposited by RF magnetron sputtering system were annealed by furnace and insitu heat treatment methods. We investigated the effect of heat treatment method on physical properties of ZnO thin films. The structural and optical properties of ZnO thin films were improved by heat treatment. Through the annealing treatment of ZnO film by furnace, the good crystallinity and ultraviolet emission were obtained. These results are attributed to the improved formation of Zn-O bond in ZnO thin film annealed at by furnace. We confirm that the formation of Zn-O bond plays an important role in obtaining the excellent structural and optical properties of ZnO thin films.

• Journal of Information Display
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• 제12권1호
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• pp.29-35
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• 2011

In this study, plasma display panels with three different cell volumes were prepared by changing the spaces between the vertical barrier ribs into two and three times the reference structure. The discharge gap and area of the segmented ITO electrode were the same for the three cases, and Ne.20%Xe gas was used. The luminance and luminance efficiency were measured using applied voltage variations. The time evolution and intensity distribution of the infrared, which are related to the vacuum ultraviolet, were observed via intensified, charged, coupled device, and the visible-light intensity profiles were observed using PR-900 to analyze the discharge phenomena in the discharge cell.

• 한국진공학회지
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• 제16권2호
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• pp.145-152
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• 2007

자외선 광여기 전자현미경 (Ultraviolet - Photoelectron Emission Microscopy: UV-PEEM)을 이용하여 Si (001)과 (113) 표면에 Ge을 증착하면서 실시간으로 나노구조의 형성과 크기 및 형태 변화과정을 조사하였다. Ge은 PBEM에 부착된 e-beam 증착기를 이용하여 $450-550^{\circ}C$ 온도에서 in situ로 증착하면서 표면의 변화를 PEEM으로 관찰하였다. Ge을 ${\sim}0.4\;ML/min$의 증착율로 ${\sim}4\;ML$ 이상 두께로 증착했을 때, 두 Si 표면에서 Ge의 균일한 변형층(strained layer) 위에 island 구조가 형성되었다. 초기에 형성된 원형 모양의 island는 연속적인 Ge 증착에 따라, ripening 과정에 의해 크기가 점차 성장되었고 밀도는 감소하였으나, 형태는 원형 모양을 유지하였다. 시료 성장 후 공기 중 AFM 측정 결과, Si(001) 표면에는 dome 형태의 Ge island가 Si(113) 표면에는 윗면이 평판하고 다면의 옆면을 지닌 island 구조가 형성됨이 확인되었다. 반면에 ${\sim}0.15\;ML/min$의 낮은 증착율로 Ge을 증착했을 때, Si(113) 표면에서 원형의 Ge island가 길죽한(elongated) 형태의 나노선 구조로 변형됨이 관찰되었다. 또한, 계속적인 Ge 증착 두께를 증가시킴에 따라 표면에는 새로운 island가 형성되지 않고, 기존의 island들이 점차 길이 방향으로 크기가 증가하면서 [$33\bar{2}$] 방향으로 배열하였다. 이와 같은 Ge 나노구조의 형성과 형태 변화는 나노구조 형성과정에서 변형이완(strain relaxation)과 가원자(adatom)의 표면 동역학적 효과와 깊은 관련이 있는 것으로 분석된다.