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崔榮求,鄭光祐,任興淳,金相俠 圓光大學校 基礎自然科學硏究所 1996 基礎科學硏究誌 Vol.15 No.1
Nd:YAG 레이저의 2차 조화파(532㎚)를 사용한 레이저증착방법으로 Pt/Ti/SiO_2/Si 기판위에 Pb(Zr_0.52ti_0.48)O_3(PZT)박막을 제조하였다. PZT박막의 증착에 필요한 최적조건을 찾기 위해서 산소분압, 실리콘기판의 온도, 레이저세기 등을 변화시키면서 증착된 박막의 특성들을 관찰하였다. 최적조건은 기판과 타겟사이의 거리가 20㎜일때 산소분압은 3 torr, 레이저 세기는 1.5 J/㎠, 실리콘기판의 온도는 823―848 K임을 알 수 있다. 이들 조건으로부터 증착된 PZT 박막의 구조는 완전한 perovskite 구조를 나타냈으며, 화학적 조성은 벌크 PZT 타켓의 조성과 동일하였다. C―V 분석결과는 전형적인 강유전체 박막의 이력곡선을 보여주었으며, 박막의 두께가 0.18㎛일 때 유전상수값이 745로 나타났다. Pb(Zr_0.52ti_0.48)O_3(PZT)thin films were deposited onto the Pt/Ti/SiO_2/Si substrate by pulsed laser deposition (PZT) of second harmonic wavelength(532㎚) of Nd:YAG laser. In order to determine optimum parameters for thin film deposition, the characteristics of thin films were investigated as a function of oxygen background pressure, substrate temperature, and laser fluence. When the distance between substrate and bulk PZT target os set to 20㎜, the optimum parameters are observed to be 3 torr of oxygen pressure, 1.5 J/㎠ of laser fluence, and 823―848 K range of substrate temperature. From the measurement of the glancing X―ray diffraction, energy dispersive X―ray, and X―ray photoelectron spectra, it is concluded that the PZT thn film represents a perovskite structure and its chemical composition is very similar to that of PZT bulk target. Capacitance―Voltage hysteresis loop measurements show also a typical characteristics of ferroelectric thin film. The dielectric constant is found to be 745 for the 0.18㎛ thickness of PZT thin film.
Kim, Sang-Mook,Kim, Ki Seok,Jung, Gun Young,Baek, Jong Hyeob,Jeong, Hyun,Jeong, Mun Seok Institute of Physics [etc.] 2009 Journal of Physics. D, Applied Physics Vol.42 No.15
<P>We compare the characteristics of photonic crystal (PC) light-emitting diodes (LEDs) with the same hole pattern density of 12 ea µm<SUP>−2</SUP>. The PC LED with periodic hole structure demonstrated an increased output power, improved external efficiency at high current operation and uniform radiation owing to the periodic nanoscale features generating a photonic band gap (PBG), when compared with those of the random hole (RH) LED. The electroluminescence images obtained by confocal scanning electroluminescence microscopy (CSEM) show the difference of light emission propagation from the random and periodic structures.</P>