Highly self-cleaning thin films of TiO2-SiO2 co-doped with Ag and F are prepared by the sol-gel method. The asprepared thin films consist of bottom SiO2 and top TiO2 layers which are modified by doping with F, Ag and F-Ag elements. XRD analysis confirms that the prepared thin film is a crystalline anatase phase. UV-vis spectra show that the light absorption of Ag-F-TiO2/SiO2 thin films is tuned in the visible region. The self-cleaning properties of the prepared films are evaluated by a water contact angle measurement under UV light irradiation. The photocatalytic performances of the thin films are studied using methylene blue dye under both UV and visible light irradiation. The Ag-F-TiO2/SiO2 thin films exhibit higher photocatalytic activity under both UV and visible light compared with other samples of pure TiO2, Ag-doped TiO2, and F-doped TiO2 films.
ZnMgBeGaO/Ag/ZnMgBeGaO multilayer structures were sputter grown and characterized in detail. Results indicated that the electrical properties of the ZnMgBeGaO films were significantly improved by inserting an Ag layer with proper thickness (~ 10 nm). Structures with thicker Ag films showed much lower optical transmission, although the electrical conductivity was further improved. It was also observed that the electrical properties of the multilayer structure were sizably improved by annealing in vacuum (~35% at 300 oC). The optimum ZnMgBeGaO(20nm)/Ag(10nm)/ZnMgBeGaO(20nm) structure exhibited an electrical resistivity of ~2.6 × 10−5 Ωcm (after annealing), energy bandgap of ~3.75 eV, and optical transmittance of 65%~ 95 % over the visible wavelength range, representing a significant improvement in characteristics versus previously reported transparent conductive materials.
The effects of the deposition and annealing temperature on the structural, electrical and opticalproperties of Ag doped ZnO (ZnO:Ag) thin films were investigated. All of the films were deposited with a 2wt%Ag2O-doped ZnO target using an e-beam evaporator. The substrate temperature varied from room temperature(RT) to 250oC. An undoped ZnO thin film was also fabricated at 150oC as a reference. The as-grown films wereannealed in temperatures ranging from 350 to 650oC for 5h in air. The Ag content in the film decreased asthe deposition and the post-annealing temperature increased due to the evaporation of the Ag in the film.During the annealing process, grain growth occurred, as confirmed from XRD and SEM results. The as-grownfilm deposited at RT showed n-type conduction; however, the films deposited at higher temperatures showedp-type conduction. The films fabricated at 150oC revealed the highest hole concentration of 3.98×1019cm-3 anda resistivity of 0.347Ω·cm. The RT PL spectra of the as-grown ZnO:Ag films exhibited very weak emissionintensity compared to undoped ZnO; moreover, the emission intensities became stronger as the annealingtemperature increased with two main emission bands of near band-edge UV and defect-related greenluminescence exhibited. The film deposited at 150oC and annealed at 350oC exhibited the lowest value of Ivis/Iuv of 0.05.
Thin Ag films deposited onto substrates by DC magnetron sputtering and thereafter annealed ,it temperatures 100-50 are investigated by scanning tunneling and atomic forte microscopy. It is shown that the film surface topography and microstructure are considerably changed as a result of annealing. To provide a quantitative estimation of the surface topography changes of Ag films the surface fractal dimension was calculated. Elasticity and hardness of the films are studied by a nanoindentation technique. The films are found to have value of elastic modulus close to that of bulk silver while their hardness and yield stress are essentially higher.
TiO2/Ag 계 적층형 투명 열절연 박막의 최적 제작조건 설정을 위한 기초 연구로써, 스퍼터조건에 따른 결정구조 및 광학특성 변화거동을 관찰하였다. 반응성 스퍼터링에 의한 TiO2박막 제작조건에 따른 결정구조 및 광학특성 변화거동을 관찰하였다. 반응성 스퍼터링에 의한 TiO2 박막 제작시 Po2/PAr≤0.2에서는 α-TiO2 의 결정구조였으나, Po2/PAr≤0.2에서는 기판 온도(RT-370˚C) 및 열처리 온도(100-800˚C)에 관계없이 non-stoichiometric 화합물로 판명되어, 산소 분압비가 TiO2 의 조성제어에 가장 중요한 변수로 나타났다. TiO2 박막은 열처리 온도의 증가(100-800˚C)에 따라 굴절률이 증가(2.19-2.37)하는 경향이었는데, 이는 박막의 밀도증가에서 기인하는 것으로 판단된다. Ag 박막은(111)면과 (200)면이 우세한 결정립으로, 기판 온도(RT-370˚C) 및 열처리(100-800˚C)에 따라 등축상의 결정립 성장을 관찰할 수 있었다.
Transfer matrix를 사용하여 TiO2 및 Ag 단일 박막과 TiO2/Ag/TiO2 다층 박막의 두계에 따른 투과도 특성을 예측하였으며, 이를 실제 스퍼터 증착하여 제조한 박막의 광학 특성과 비교하였다. TiO2 및 Ag 박막에서는 복소굴절률을 사용하므로써 실제 증착박막에서 측정된 특성과 근접한 투과도 곡선의 예측이 가능하였다. TiO2/Ag/TiO2 3층 박막의 광학 특성은 Ag의 TiO2층으로의 확산 및 응집에 의해 transfer matrix로 예측한 투과도 특성과 전혀 다른 거동을 나타내었다. 그러나 4nm 및 6nm 두계의 Ti 박막을 확산방지층으로 증착한 TiO2/Ti/Ag/Ti/TiO2 구조의 5층 박막에서는 transfer matrix를 사용하여 예측한 TiO2/Ag/TiO2 3층 박막의 투과도 곡선과 유사한 광학 특성을 얻을 수 있었다.