서지주요정보
반도체성 TiO2부동태 피막 및 수소 장입된 $TiO_2$부동태 피막에서 전자결함에 대한 연구 = Electronic defects in uncharged and hydrogen-charged semiconductive passivating $TiO_2$ films
서명 / 저자 반도체성 TiO2부동태 피막 및 수소 장입된 $TiO_2$부동태 피막에서 전자결함에 대한 연구 = Electronic defects in uncharged and hydrogen-charged semiconductive passivating $TiO_2$ films / 김창하.
저자명 김창하 ; Kim, Chang-Ha
발행사항 [대전 : 한국과학기술원, 1991].
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8001671

소장위치/청구기호

학술문화관(문화관) 보존서고

DMS 9101

SMS전송

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초록정보

Electronic defects, i.e., shallow and deep donor, in uncharged and hydrogen-charged passivating $TiO_2$ films have been investigated by impedance measurement. Donor distribution in the crystalline and amorphous passivating $TiO_2$ films was detailed. In addition, an investigation was focussed on how hydrogen as a donor contributes to electronic conduction within the hydrogen-injected $TiO_2$ film. For this purpose, impedance of the $TiO_2$ film was measured as a function of applied potential and frequency. In an attempt to confirm the crystal structure of the film, the X-ray and TEM diffraction analyses were made. The passive films on titanium were prepared galvanostatically in 1.0N $H_2SO_4$ solution with 5 and 10 mA $cm^{-2}$ at formation potentials ranging between 5 and 50 $V_{SCE}$. Hydrogen injection was performed into fresh films by scanning the applied potential range -1.7 to -1.5 $V_{SCE}$ and back at a rate of 2mV $S^{-1}$ in a 0.1N NaOH solution. The impedance measurement was conducted in 0.1N NaOH solution by superimposing an ac voltage of 5 mV amplitude over the frequency ranging from $10^2$ to $10^4$ Hz on a dc potential. The crystal structure of the passivating $TiO_2$ film was experimentally substantiated by the TEM and X-ray diffraction analyses. The 5 $V_{SCE}$ -passive film was in an amorphous state, but the passive film formed more positive than 10 $V_{SCE}$ showed polycrystalline structure. The Mott-Schottky plot proved to be nonlinear for the passive films irrespective of formation potential. From the analysis of the nonlinear Mott-Schottky plot obtained from the 30 $V_{SCE}$ -passive film(83nm in thickness) and 50 $V_{SCE}$ -passive film (106nm in thickness), it is concluded that the donor concentration remains constant from the electrolyte/film interface up to about 50% of the total film thickness and then increases considerably with distance toward the film/metal interface. From the 5 $V_{SCE}$ -passive film (22nm in thickness), we deduced that the nonlinearity in the Mott-Schottky plot results due to the presence of multiple donor levels in the passive film. Hydrogen injected into the film increases both donor concentration and electronic conductivity. The experimental results suggest that hydrogen donates electron to the conduction band inside the passive film. From the analysis of frequency dependence of the electronic conductivity, it is concluded that electrons which hydrogen donates in the conduction band flows in the interior of the grain and moves across the grain boundary by hopping. It is observed that flatband potential shifts to more positive potentials due to the adsorption of proton on the film surface.

서지기타정보

서지기타정보
청구기호 {DMS 9101
형태사항 v, 144 p. : 삽도 ; 26 cm
언어 한국어
일반주기 저자명의 영문표기 : Chang-Ha Kim
지도교수의 한글표기 : 변수일
지도교수의 영문표기 : Su-Il Pyun
학위논문 학위논문(박사) - 한국과학기술원 : 재료공학과,
서지주기 참고문헌 : p. 74-86
주제 Titanium dioxide
DX centers (Solid state physics)
Semiconductor films
부동태 피막 --과학기술용어시소러스
티탄산염 --과학기술용어시소러스
수소 --과학기술용어시소러스
반도성 --과학기술용어시소러스
Passivity (Chemistry)
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