Gd thin films with different thickness （about 10 nm and 0.5 nm） were deposited on Si（100） by laser molecular beam epitaxy （LMBE）. Thickness dependence of the initial oxidation behaviors of Gd films was studied b...Gd thin films with different thickness （about 10 nm and 0.5 nm） were deposited on Si（100） by laser molecular beam epitaxy （LMBE）. Thickness dependence of the initial oxidation behaviors of Gd films was studied based on the in situ X-ray photoelectron spectroscopy （XPS） and ultraviolet photoelectron spectroscopy （UPS） analysis under ultra-high vacuum （UHV） condition. When the thin film is around 10 urn, the XPS results show that Gd is extremely reactive with oxygen forming Gd oxides and the oxides of Gd are easily hygroscopic. The UPS results show that the Gd 4fhas a double-peak structure and the double-peak structure of Gd 4fevolves into a single-peak feature after exposing to air. When the thickness of the Gd film decreases to about 0.5 urn, the reactivity of Gd film with oxygen is decreased by the diffusion of Si component into Gd layers based on the XPS and UPS results. It is suggested that the silicon atoms segregate at the grain boundaries of Gd film to form a barrier, which block the further diffusion of oxygen and water vapor into the Gd layers.展开更多
Gd-Co alloy films were synthesized by potentiostatic electrolysis on Cu substrates in urea-acetamide-NaBr-KBr melt at 353 K. The electroreduction of Co^2＋ and Gd^3＋ was investigated by cyclic voltammetry. The reduct...Gd-Co alloy films were synthesized by potentiostatic electrolysis on Cu substrates in urea-acetamide-NaBr-KBr melt at 353 K. The electroreduction of Co^2＋ and Gd^3＋ was investigated by cyclic voltammetry. The reduction of Co^2＋ is an irreversible process. Gd^3＋ cannot be reduced alone, but it can be inductively co-deposited with Co^2＋. Both the Gd content and microstructure of the prepared Gd-Co alloy films can be controlled by the deposited potential. The content of Gd was analyzed using an inductively coupled plasma emission spectrometer （ICPES）, and the microstructure was observed by scanning electron micrograph （SEM）. The films were crystallized by heat-treatment at 823 K for 30 s in Ar atmosphere, and then were investigated by XRD. The hysteresis loops of the Gd-Co alloy films were measured by a vibrating sample magnetometer （VSM）. The experimental results reveal that the deposited Gd-Co alloy films are amorphous, while the annealing causes the samples to change from amorphous to polycrystalline, thus enhancing their magnetocrystalline anisotropy and coercivity. Moreover, the magnetic properties of the Gd-Co alloy films depend strongly on the Gd content.展开更多
Gd2O3 thin films as high-κ gate dielectrics were deposited directly on Si（001） substrates by magnetron sputtering at a pressure of 1.3 Pa and different temperatures. X-ray diffraction results revealed that all the ...Gd2O3 thin films as high-κ gate dielectrics were deposited directly on Si（001） substrates by magnetron sputtering at a pressure of 1.3 Pa and different temperatures. X-ray diffraction results revealed that all the films grown from 450 to 570 ℃ were crystalline, and the Gd2O3 thin films consisted of a mixture of cubic and monoclinic phases. The growth temperature was a critical parameter for the phase constituents and their relative amount. Low temperature was favorable for the formation of cubic phase while higher temperature gave rise to more monoclinic phase. All the Gd2O3 thin films grown from different temperatures exhibited acceptable electrical properties, such as low leakage current density （JL） of 10-5 A/cm^2 at zero bias with capacitance equivalent SiO2 thickness in the range of 6-13 nm. Through the comparison between films grown at 450 and 570 ℃, the existence of monoclinic phase caused an increase in JL by nearly one order of magnitude and a reduction of effective dielectric constant from 17 to 9.展开更多
ESR studies have been undertaken for various chemical composition of electron beam evapo- rated a-Si_(1-x)Gd_x films with 0<x≤10at%.The experimental results show that the g value changes with (2.0043±0.0001)...ESR studies have been undertaken for various chemical composition of electron beam evapo- rated a-Si_(1-x)Gd_x films with 0<x≤10at%.The experimental results show that the g value changes with (2.0043±0.0001)≤g≤(2.0054±0.0001),the line shape factor l changes with(2.77±0.01)≤l≤(3.10± 0.01)and the linewidth △B_(pp)changes with 6.40×10^(-4)≤△B_(pp)≤7.00×10^(-4)T.The experimental results were analysed with Barnes S.E.dynamic theory of ESR spectrum based on the characteristics of the ESR parameters.It was shown that the changes of ESR parameters depend on the compensation of Gd atoms for the dangling bonds in a-Si film,and the exchange interaction between the conduction electrons and the spins in the host materials.展开更多
在353K的乙酰胺-尿素-N aB r熔体中,P t、Cu电极上,Co(Ⅱ)+2e→Co(0)是一步完全不可逆反应,测得0.060m o l.L-1CoC l2-乙酰胺-尿素-N aB r中,Co(Ⅱ)在P t上,传递系数α=0.28,扩散系数D0=4.68×10-5cm2.-s 1,Cu上α=0.28,D0=4.06...在353K的乙酰胺-尿素-N aB r熔体中,P t、Cu电极上,Co(Ⅱ)+2e→Co(0)是一步完全不可逆反应,测得0.060m o l.L-1CoC l2-乙酰胺-尿素-N aB r中,Co(Ⅱ)在P t上,传递系数α=0.28,扩散系数D0=4.68×10-5cm2.-s 1,Cu上α=0.28,D0=4.06×1-0 7cm2.-s 1。G d(Ⅲ)不能单独还原为G d(0),但可以被Co(Ⅱ)诱导共沉积。由恒电位电解法得到非晶态的G d-Co合金,G d的含量随阴极电位的负移,G d(Ⅲ)/N i(Ⅱ)摩尔比增大以及电解时间延长而增大。展开更多
基金Funded by the Key Laboratory of National Defense Science and Technology(No.9140c6806080c68)
文摘Gd thin films with different thickness （about 10 nm and 0.5 nm） were deposited on Si（100） by laser molecular beam epitaxy （LMBE）. Thickness dependence of the initial oxidation behaviors of Gd films was studied based on the in situ X-ray photoelectron spectroscopy （XPS） and ultraviolet photoelectron spectroscopy （UPS） analysis under ultra-high vacuum （UHV） condition. When the thin film is around 10 urn, the XPS results show that Gd is extremely reactive with oxygen forming Gd oxides and the oxides of Gd are easily hygroscopic. The UPS results show that the Gd 4fhas a double-peak structure and the double-peak structure of Gd 4fevolves into a single-peak feature after exposing to air. When the thickness of the Gd film decreases to about 0.5 urn, the reactivity of Gd film with oxygen is decreased by the diffusion of Si component into Gd layers based on the XPS and UPS results. It is suggested that the silicon atoms segregate at the grain boundaries of Gd film to form a barrier, which block the further diffusion of oxygen and water vapor into the Gd layers.
基金financially supported by the Science Foundation of the Educational Department of Fujian Prov-ince (No. 2008F5021)the Natural Science Foundation of Fujian Province (No. A0510013)the National Natural Science Foundation of China (No. 60676055)
文摘Gd-Co alloy films were synthesized by potentiostatic electrolysis on Cu substrates in urea-acetamide-NaBr-KBr melt at 353 K. The electroreduction of Co^2＋ and Gd^3＋ was investigated by cyclic voltammetry. The reduction of Co^2＋ is an irreversible process. Gd^3＋ cannot be reduced alone, but it can be inductively co-deposited with Co^2＋. Both the Gd content and microstructure of the prepared Gd-Co alloy films can be controlled by the deposited potential. The content of Gd was analyzed using an inductively coupled plasma emission spectrometer （ICPES）, and the microstructure was observed by scanning electron micrograph （SEM）. The films were crystallized by heat-treatment at 823 K for 30 s in Ar atmosphere, and then were investigated by XRD. The hysteresis loops of the Gd-Co alloy films were measured by a vibrating sample magnetometer （VSM）. The experimental results reveal that the deposited Gd-Co alloy films are amorphous, while the annealing causes the samples to change from amorphous to polycrystalline, thus enhancing their magnetocrystalline anisotropy and coercivity. Moreover, the magnetic properties of the Gd-Co alloy films depend strongly on the Gd content.
基金General Research Institute for Nonferrous Metals Research Fund (82262)
文摘Gd2O3 thin films as high-κ gate dielectrics were deposited directly on Si（001） substrates by magnetron sputtering at a pressure of 1.3 Pa and different temperatures. X-ray diffraction results revealed that all the films grown from 450 to 570 ℃ were crystalline, and the Gd2O3 thin films consisted of a mixture of cubic and monoclinic phases. The growth temperature was a critical parameter for the phase constituents and their relative amount. Low temperature was favorable for the formation of cubic phase while higher temperature gave rise to more monoclinic phase. All the Gd2O3 thin films grown from different temperatures exhibited acceptable electrical properties, such as low leakage current density （JL） of 10-5 A/cm^2 at zero bias with capacitance equivalent SiO2 thickness in the range of 6-13 nm. Through the comparison between films grown at 450 and 570 ℃, the existence of monoclinic phase caused an increase in JL by nearly one order of magnitude and a reduction of effective dielectric constant from 17 to 9.
文摘ESR studies have been undertaken for various chemical composition of electron beam evapo- rated a-Si_(1-x)Gd_x films with 0<x≤10at%.The experimental results show that the g value changes with (2.0043±0.0001)≤g≤(2.0054±0.0001),the line shape factor l changes with(2.77±0.01)≤l≤(3.10± 0.01)and the linewidth △B_(pp)changes with 6.40×10^(-4)≤△B_(pp)≤7.00×10^(-4)T.The experimental results were analysed with Barnes S.E.dynamic theory of ESR spectrum based on the characteristics of the ESR parameters.It was shown that the changes of ESR parameters depend on the compensation of Gd atoms for the dangling bonds in a-Si film,and the exchange interaction between the conduction electrons and the spins in the host materials.
