A new approach is proposed to accurately determine the thickness of films, especially for ultra-thin films,through spectrum-fitting with the assistance of an interference layer. The determination limit can reach even ...A new approach is proposed to accurately determine the thickness of films, especially for ultra-thin films,through spectrum-fitting with the assistance of an interference layer. The determination limit can reach even less than 1 nm. Its accuracy is far better than that of the traditional methods. This determination method is verified by experiments, and the determination limit is at least 3.5 nm compared with the results of atomic force microscope（AFM）. Furthermore, a double interference-aided spectra fitting method is proposed to reduce the requirements of the determination instruments, which thus allows one to determine the film＇s thickness with a low-precision common spectrometer and to greatly lower the cost. It is a very high-precision determination method for on-site and in-situ applications, especially for ultra-thin films.展开更多
A Ce^（3＋）tion-doped α-Na YF_4 single crystal of high quality is grown successfully by an improved flux Bridgman method under the conditions of taking the chemical raw composition of Na F：KF：YF_3：CeF_3 in the mo...A Ce^（3＋）tion-doped α-Na YF_4 single crystal of high quality is grown successfully by an improved flux Bridgman method under the conditions of taking the chemical raw composition of Na F：KF：YF_3：CeF_3 in the molar ratio of30∶18∶48∶4, where the KF is shown to be an effective assistant flux. The x ray diffraction, absorption spectra,excitation spectra, and emission spectra of the Ce^（3＋）t-doped α-Na YF_4 single crystal are measured to investigate the phase and optical properties of the single crystals. The absorption spectrum of the Ce^（3＋）t：α-Na YF_4 shows a strong band that peaks at the wavelength of 300 nm. The emission spectrum of the Ce^（3＋）t：α-Na YF_4 emits an intense ultraviolet（UV） band at the wavelength of 332 nm under the excitation of 300 nm light. Two separated luminous bands of 330 and 350 nm, which correspond to the transitions 5d → 2F25∕2and 5d → F7∕2, can be obtained by Gauss fitting. The strong emission intensity at the UV band and the excellent optical transmission in the range of UV wavelengths indicate that Ce^（3＋）t：α-Na YF_4 single crystals can be considered as a promising material for UV lasers.展开更多
基金supported by the Shanghai Science and Technology Foundation(Nos.13JC1405902,15DZ2282100,and 16DZ2290600)the Youth Innovation Promotion Association CAS(No.2012189)the National Natural Science Foundation of China(Nos.61223006 and 61376053)
文摘A new approach is proposed to accurately determine the thickness of films, especially for ultra-thin films,through spectrum-fitting with the assistance of an interference layer. The determination limit can reach even less than 1 nm. Its accuracy is far better than that of the traditional methods. This determination method is verified by experiments, and the determination limit is at least 3.5 nm compared with the results of atomic force microscope（AFM）. Furthermore, a double interference-aided spectra fitting method is proposed to reduce the requirements of the determination instruments, which thus allows one to determine the film＇s thickness with a low-precision common spectrometer and to greatly lower the cost. It is a very high-precision determination method for on-site and in-situ applications, especially for ultra-thin films.
基金supported by the National Natural Science Foundation of China(Nos.51472125 and51272109)the K.C.Wong Magna Fund of Ningbo University
文摘A Ce^（3＋）tion-doped α-Na YF_4 single crystal of high quality is grown successfully by an improved flux Bridgman method under the conditions of taking the chemical raw composition of Na F：KF：YF_3：CeF_3 in the molar ratio of30∶18∶48∶4, where the KF is shown to be an effective assistant flux. The x ray diffraction, absorption spectra,excitation spectra, and emission spectra of the Ce^（3＋）t-doped α-Na YF_4 single crystal are measured to investigate the phase and optical properties of the single crystals. The absorption spectrum of the Ce^（3＋）t：α-Na YF_4 shows a strong band that peaks at the wavelength of 300 nm. The emission spectrum of the Ce^（3＋）t：α-Na YF_4 emits an intense ultraviolet（UV） band at the wavelength of 332 nm under the excitation of 300 nm light. Two separated luminous bands of 330 and 350 nm, which correspond to the transitions 5d → 2F25∕2and 5d → F7∕2, can be obtained by Gauss fitting. The strong emission intensity at the UV band and the excellent optical transmission in the range of UV wavelengths indicate that Ce^（3＋）t：α-Na YF_4 single crystals can be considered as a promising material for UV lasers.
