The role of hydrogen in hydrogenated microcrystalline silicon film and in deposition process with VHF-PECVD technique

The role of hydrogen in hydrogenated microcrystalline silicon ($\mu $c-Si:H) thin films in deposition processes with very high frequency plasma-enhanced chemical vapour deposition (VHF-PECVD) technique have been investigated in this paper. With \textit{in situ} optical emission spectroscopy (OES) diagnosis during the fabrication of $\mu $c-Si:H thin films under different plasma excitation frequency $\nu _{\rm e }$ (60MHz--90MHz), the characteristic peak intensities ($I_{{\rm SiH}^*}$, $I_{{\rm H}\alpha^*}$ and $I_{{\rm H}\beta ^*}$) in SiHVHF-PECVD技术 氢化微晶硅 光发射光谱 薄膜学VHF-PECVD technique, hydrogenated microcrystalline silicon, role of hydrogen, optical emission spectroscopyProject supported by the Natural Science Foundation of Guangdong Province, China (Grant No 05300378), the State Key Development Program for Basic Research of China (Grant Nos G2000028202 and G2000028203) and the Program on Natural Science of Jinan University, Guangzhou, China (Grant No 51204056).2005-11-252005-11-252006-01-05The role of hydrogen in hydrogenated microcrystalline silicon （μc-Si：H） thin films in deposition processes with very high frequency plasma-enhanced chemical vapour deposition （VHF-PECVD） technique have been investigated in this paper. With in situ optical emission spectroscopy （OES） diagnosis during the fabrication of μc-Si：H thin films under different plasma excitation frequency Ve （60MHz-90MHz）, the characteristic peak intensities （IsiH＊, IHα＊ and IHβ＊ ） in SiH4＋H2 plasma and the ratio of （IHα＊ ＋ IHβ＊ ） to IsiH＊ were measured; all the characteristic peak intensities and the ratio （IHα＊ ＋ IHβ＊ ）/IsiH＊ are increased with plasma excitation frequency. It is identified that high plasma excitation frequency is favourable to promote the decomposition of SiH4＋H2 to produce atomic hydrogen and SiHx radicals. The influences of atomic hydrogen on structural properties and that of SiHx radicals on deposition rate of μc-Si：H thin films have been studied through Raman spectra and thickness measurements, respectively. It can be concluded that both the crystalline volume fraction and deposition rate are enhanced with the increase of plasma excitation frequency, which is in good accord with the OES results. By means of FTIR measurements, hydrogen contents of μc-Si：H thin films deposited at different plasma excitation frequency have been evaluated from the integrated intensity of wagging mode near 640 cm^-1. The hydrogen contents vary from 4% to 5%, which are much lower than those of μc-Si：H films deposited with RF-PECVD technique. This implies that μc-Si：H thin films deposited with VHF-PECVD technique usually have good stability under light-soaking.     

Effects of deposition pressure and plasma power on the growth and properties of boron-doped microcrystalline silicon films

Using diborane as doping gas, p-doped μc-Si：H layers are deposited by using the plasma enhanced chemical vapour deposition （PECVD） technology. The effects of deposition pressure and plasma power on the growth and the properties of μc-Si：H layers are investigated. The results show that the deposition rate, the electrical and the structural properties are all strongly dependent on deposition pressure and plasma power. Boron-doped μc-Si：H films with a dark conductivity as high as 1.42 Ω^-1·cm^-1 and a crystallinity of above 50% are obtained. With this p-layer, μc-Si：H solar cells are fabricated. In addition, the mechanism for the effects of deposition pressure and plasma power on the growth and the properties of boron-doped μc-Si：H layers is discussed.     

The high deposition of microcrystalline silicon thin film by very high frequency plasma enhanced chemical vapour deposition and the fabrication of solar cells

This paper reports that the intrinsic microcrystalline silicon ($\mu $c-Si:H) films are prepared with plasma enhanced chemical vapour deposition from silane/hydrogen mixtures at 200\du\ with the aim to increase the deposition rate. An increase of the deposition rate to 0.88\,nm/s is obtained by using a plasma excitation frequency of 75\,MHz. This increase is obtained by the combination of a higher deposition pressure, an increased silane concentration, and higher discharge powers. In addition, the transient behaviour, which can decrease the film crystallinity, could be prevented by filling the background gas with Hchemical vapour deposition, plasma deposition, solar cells, crystallinityProgram supported by the State Key Development Program for Basic Research of China (Grant No 2006CB202601), and Basic Research Project of Henan Province in China (Grant No 072300410140).7280N, 7830G, 8115HThis paper reports that the intrinsic microcrystalline silicon ($\mu $c-Si:H) films are prepared with plasma enhanced chemical vapour deposition from silane/hydrogen mixtures at 200\du\ with the aim to increase the deposition rate. An increase of the deposition rate to 0.88\,nm/s is obtained by using a plasma excitation frequency of 75\,MHz. This increase is obtained by the combination of a higher deposition pressure, an increased silane concentration, and higher discharge powers. In addition, the transient behaviour, which can decrease the film crystallinity, could be prevented by filling the background gas with Hchemical vapour deposition, plasma deposition, solar cells, crystallinityProgram supported by the State Key Development Program for Basic Research of China (Grant No 2006CB202601), and Basic Research Project of Henan Province in China (Grant No 072300410140).7280N, 7830G, 8115HThis paper reports that the intrinsic microcrystalline silicon ($\mu $c-Si:H) films are prepared with plasma enhanced chemical vapour deposition from silane/hydrogen mixtures at 200\du\ with the aim to increase the deposition rate. An increase of the deposition rate to 0.88\,nm/s is obtained by using a plasma excitation frequency of 75\,MHz. This increase is obtained by the combination of a higher deposition pressure, an increased silane concentration, and higher discharge powers. In addition, the transient behaviour, which can decrease the film crystallinity, could be prevented by filling the background gas with Hchemical vapour deposition, plasma deposition, solar cells, crystallinityProgram supported by the State Key Development Program for Basic Research of China (Grant No 2006CB202601), and Basic Research Project of Henan Province in China (Grant No 072300410140).7280N, 7830G, 8115HThis paper reports that the intrinsic microcrystalline silicon ($\mu $c-Si:H) films are prepared with plasma enhanced chemical vapour deposition from silane/hydrogen mixtures at 200\du\ with the aim to increase the deposition rate. An increase of the deposition rate to 0.88\,nm/s is obtained by using a plasma excitation frequency of 75\,MHz. This increase is obtained by the combination of a higher deposition pressure, an increased silane concentration, and higher discharge powers. In addition, the transient behaviour, which can decrease the film crystallinity, could be prevented by filling the background gas with Hchemical vapour deposition, plasma deposition, solar cells, crystallinityProgram supported by the State Key Development Program for Basic Research of China (Grant No 2006CB202601), and Basic Research Project of Henan Province in China (Grant No 072300410140).7280N, 7830G, 8115HThis paper reports that the intrinsic microcrystalline silicon ($\mu $c-Si:H) films are prepared with plasma enhanced chemical vapour deposition from silane/hydrogen mixtures at 200\du\ with the aim to increase the deposition rate. An increase of the deposition rate to 0.88\,nm/s is obtained by using a plasma excitation frequency of 75\,MHz. This increase is obtained by the combination of a higher deposition pressure, an increased silane concentration, and higher discharge powers. In addition, the transient behaviour, which can decrease the film crystallinity, could be prevented by filling the background gas with H$_{2}$ prior to plasma ignition, and selecting proper discharging time after silane flow injection. Material prepared under these conditions at a deposition rate of 0.78\,nm/s maintains higher crystallinity and fine electronic properties. By H-plasma treatment before i-layer deposition, single junction $\mu $c-Si:H solar cells with 5.5{\%} efficiency are fabricated.     

Effect of substrate temperature on the growth and properties of boron-doped microcrystalline silicon films

Highly conductive boron-doped hydrogenated microcrystalline silicon (\mu c-Si:H) films are prepared by very high frequency plasma enhanced chemical vapour deposition (VHF PECVD) at the substrate temperatures $T_{\rm S})$ ranging from 90$^\circ$C to 270$^\circ$C. The effects of $T_{\rm S}$ on the growth and properties of the films are investigated. Results indicate that the growth rate, the electrical (dark conductivity, carrier concentration and Hall mobility) and structural (crystallinity and grain size) properties are all strongly dependent on $T_{\rm S}$. As $T_{\rm S}$ increases, it is observed that 1) the growth rate initially increases and then arrives at a maximum value of 13.3 nm/min at $T_{\rm S}$=210$^\circ$C, 2) the crystalline volume fraction ($X_{\rm c})$ and the grain size increase initially, then reach their maximum values at $T_{\rm S}$=140$^\circ$C, and finally decrease, 3) the dark conductivity ($\sigma _{\rm d})$, carrier concentration and Hall mobility have a similar dependence on $T_{\rm S}$ and arrive at their maximum values at $T_{\rm S}$=190$^\circ$C. In addition, it is also observed that at a lower substrate temperature $T_{\rm S}$, a higher dopant concentration is required in order to obtain a maximum $\sigma _{\rm d}$.     

Quantum coherent effects in multi-Zeeman-sublevel atomic systems

This paper reports the experimental results on electromagnetically induced absorption （EIA） spectra observed in the system which does not satisfy completely the conditions given by Lezama et al [1999 Phys. Rev. A 59 4732]. EIA signals on the transitions in the Cs D2 line are able to be observed, where Fg ←→ Fe = Fg-1 as open systems. Theoretical model of Lezama et al is good for the case Fg ←→ Fc = Fg ＋ 1, considering spontaneous transfer of atomic coherences or populations this model is not able to explain our experimental results obtained in the case Fg ←→ Fe = Fg - 1. This paper offers a theoretical model which is able to well explain the case Fg ←→ Fc = Fg - 1. It also uses this theoretical model to explain the split and shift of EIA peaks, which have been obtained in experiments.     

用H-W-ECR CVD系统实现氢化非晶硅薄膜在氢气环境下同时进行化学热退火和光诱导退火的研究

为了研究氢化非晶硅薄膜的稳定性，我们设计了一个在原子氢气氛中热退火的同时进行光诱导退火的实验(TLAH)。实验装置是由传统的微波电子回旋共振化学气相沉积系统改造而成为热丝辅助微波电子回旋共振化学气相沉积系统。为了对这一退火方法进行比较，对样品还进行了热退火、热退火同时进行光诱导退火。同时，为了定量地分析光电导衰退，我们假设光电导衰退遵循扩展指数规律：1/σph=1/σs-(1/σs-1/σ0)exp[-(t/τ)β]，这里扩展指数参数β 和时间常数 τ 可从与 lnt 的线性关系中截距和斜率得到, 式中光电导饱和值σs可以通过在对数坐标系中表示的光电导和光照时间关系进行高斯拟合得到。实验结果显示：TLAH 方法可以提高氢化非晶硅薄膜的稳定性、改善其微结构和光电特性，同时还发现，光学带隙明显减小、荧光光谱显著地朝着低能方向移动。     

The effect of initial discharge conditions on the properties of microcrystalline silicon thin films and solar cells

This paper studies the effects of silane back diffusion in the initial plasma ignition stage on the properties of microcrystalline silicon ($\mu $c-Si:H) films by Raman spectroscopy and spectroscopic ellipsometry, through delaying the injection of SiH7280N, 7830G, 8115Hhttp://cpb.iphy.ac.cn/CN/10.1088/1674-1056/19/5/057205https://cpb.iphy.ac.cn/CN/article/downloadArticleFile.do?attachType=PDF&id=111771back diffusion, microcrystalline silicon, thin film, Raman crystallinityProject supported by the State Key Development Program for Basic Research of China (Grant No.~2006CB202601).This paper studies the effects of silane back diffusion in the initial plasma ignition stage on the properties of microcrystalline silicon ($\mu $c-Si:H) films by Raman spectroscopy and spectroscopic ellipsometry, through delaying the injection of SiH$_{4}$ gas to the reactor before plasma ignition. By comparing with standard discharge condition, delayed SiH$_{4}$ gas condition could prevent the back diffusion of SiH$_{4}$ from the reactor to the deposition region effectively, which induced the formation of a thick amorphous incubation layer in the interface between bulk film and glass substrate. Applying this method, it obtains the improvement of spectral response in the middle and long wavelength region by combining this method with solar cell fabrication. Finally, results are explained by modifying zero-order analytical model, and a good agreement is found between model and experiments concerning the optimum delayed injection time.back;diffusion;microcrystalline;silicon;thin;film;Raman;crystallinityThis paper studies the effects of silane back diffusion in the initial plasma ignition stage on the properties of microcrystalline silicon(μc-Si:H) films by Raman spectroscopy and spectroscopic ellipsometry,through delaying the injection of SiH4 gas to the reactor before plasma ignition.Compared with standard discharge condition,delayed SiH4 gas condition could prevent the back diffusion of SiH4 from the reactor to the deposition region effectively,which induced the formation of a thick amorphous incubation layer in the interface between bulk film and glass substrate.Applying this method,it obtains the improvement of spectral response in the middle and long wavelength region by combining this method with solar cell fabrication.Finally,results are explained by modifying zero-order analytical model,and a good agreement is found between the model and experiments concerning the optimum delayed injection time.     

Electrical and deep levels characteristics of ZnO/Si heterostructure by MOCVD deposition

ZnO films have been prepared on p-type Si substrates by metal-organic chemical vapour deposition （MOCVD） at different total gas flow rates. The current versus voltage and temperature （I - V - T） characteristics, the deep-level transient spectroscopy （DLTS） and the photoluminescence （PL） spectra of the samples were measured. DLTS shows two deep-level centres of E1 （Ec-0.13±0.02eV） and E2 （Ec-0.43±0.05eV） in sample 1202a, which has a ZnO/p-Si heterostructure. A deep level at Ec-0.13±0.01 eV was also obtained from the I -T characteristics. It was considered to be the same as E1 obtained from DLTS measurement. The emission related to this deep level center was detected by PL spectra. In addition, the energy location and the relative trap density of E1 was varied when the total gas flow rate was changed.     

The study of a new n/p tunnel recombination junction and its application in a-Si：H/μc-Si：H tandem solar cells

This paper reports that a double N layer (a-Si:H/μc-Si:H) is used to substitute the single microcrystalline silicon n layer (n-μc-Si:H) in n/p tunnel recombination junction between subcells in a-Si:H/μc-Si:H tandem solar cells. The electrical transport and optical properties of these tunnel recombination junctions are investigated by current-voltage measurement and transmission measurement. The new n/p tunnel recombination junction shows a better ohmic contact. In addition, the n/p interface is exposed to the air to examine the effect of oxidation on the tunnel recombination junction performance. The open circuit voltage and FF of a-Si:H/μc-Si:H tandem solar cell are all improved and the current leakage of the subcells can be effectively prevented efficiently when the new n/p junction is implemented as tunnel recombination junction.     

Origin of magnetization-induced anisotropy of magnetic films

It is proposed that the magnetization-induced anisotropy of magnetic films of cubic crystal structure originates from the anisotropy of atomic pair ordering, shape anisotropy, and strain anisotropy resulting from the constraint of the magnetostriction strain imposed on the film by the substratc. Calculated are the three anisotropy constants and their sum K vs temperature for Ni, Fe, and 55%Ni-Fe films; the room temperature （RT） constants vs the substrate temperature Tt during deposition or annealing after deposition for Ni and 50%Ni Co films; the RT constants vs com- position fraction for Fe-Ni films with Tt = RT, 250℃ and 450℃, Co Ni films at Tt = RT, 100℃ and 320℃, and Fe-Co films with Tt = RT and 300℃; the spread of RT K vs composition fraction for Fe Ni films; and RT △K/K vs composition fraction for Fe-Ni and Co Ni films, where △K denotes the variation of K of the film that is detached from its substrate. The calculated curves well accord with the measurements. The irrelevancy of K to the substrate material and the fast kinetics of the annealing in a field applied in the direction of the hard axis are explained reasonably.[第一段]     

In‐situ series connection of an amorphous silicon photovoltaic tandem module

Local shading during thin film deposition monolithically interconnects thin film solar cells into photovoltaic modules. This in‐situ series connection method is, for the first time, applied to an amorphous silicon tandem cell structure. Sequential maskingand mask‐shifting forms the electrical series connection in‐situ, i.e. during the sputtering and plasma depositions of the contact and semiconductor layers of the thin film solar cell structure. The resulting photovoltaic module consists of five amorphous silicon tandem cells with a total module area A_{\rm m} =12.5\mathop {\;{\rm cm}}\nolimits^2. The module exhibits a fill factor {\rm FF}_{\rm m} > 72% and a total area efficiency \eta _{\rm m} =6.2%. Thermographic imaging proves successful patterning by local shading and attributes low shunt resistances of some component cells to single pinhole formation. The dark‐shunt resistance of each cell of the module amounts to R_{{\rm sc}{\rm,dark}{\rm,cell}} > 13\;{\rm k\Omega }\;{\rm cm}^{2} and for the complete module to R_{{\rm sc}{\rm,dark}{\rm,module}} =454\;{\rm k\Omega }\;{\rm cm}^{2}. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Electron tunnelling phase time and dwell time through an associated delta potential barrier

The electron tunnelling phase time τP and dwell time τD through an associated delta potential barrier U(x) = ξδ(x) are calculated and both are in the order of 10^-17～10^-16s. The results show that the dependence of the phase time on the delta barrier parameter ξ can be described by the characteristic length lc = h^2/meξ and the characteristic energy Ec=meξ^2/h^2 of the delta barrier, where me is the electron mass, lc and Ec are assumed to be the effective width and height of the delta barrier with lcEc=ξ, respectively. It is found that TD reaches its maximum and τD = τp as the energy of the tunnelling electron is equal to Ec/2, i.e. as lc =λDB, λDB is de Broglie wave length of the electron.     

The electric and magnetic properties of epitaxially grown A0.5-xLaxSr0.5MnO3 （A=Pr, Nd） thin film

The epitaxial （single crystal-like） Pr0.4La0.1Sr0.5MnO3 （PLSMO） and Nd0.35La0.15Sr0.5MnO3 （NLSMO） thin films are prepared and characterized, and the electric and magnetic properties are examined. We find that both PLSMO and NLSMO have their own optimum deposition temperature （To） in their growing into epitaxial thin films. When the deposition temperature is higher than To, a c-axis oriented but polycrystalline thin film grows; when the deposition temperature is lower than To, the thin film tends to be a-axis oriented and also polycrystalline. The most important point is that for the epitaxial PLSMO and NLSMO thin films the electronic phase transitions are closely consistent with the magnetic phase transitions, i.e. an antiferromagnetic phase corresponds to an insulating state, a ferromagnetic phase corresponds to a metallic state and a paramagnetic phase corresponds to a semiconducting state, while for the polycrystalline thin films the electronic phase transitions are always not consistent with the magnetic transitions.     

The research on suspended ZnO nanowire field-effect transistor

This paper reports that a novel type of suspended ZnO nanowire field-effect transistors (FETs) were successfully fabricated using a photolithography process, and their electrical properties were characterized by I--V measurements. Single-crystalline ZnO nanowires were synthesized by a hydrothermal method, they were used as a suspended ZnO nanowire channel of back-gate field-effect transistors (FET). The fabricated suspended nanowire FETs showed a p-channel depletion mode, exhibited high on--off current ratio of ～10⁵. When V_DS=2.5 V, the peak transconductances of the suspended FETs were 0.396 μS, the oxide capacitance was found to be 1.547 fF, the pinch-off voltage V_TH was about 0.6 V, the electron mobility was on average 50.17 cm²/Vs. The resistivity of the ZnO nanowire channel was estimated to be 0.96× 10²Ω cm at V_GS = 0 V. These characteristics revealed that the suspended nanowire FET fabricated by the photolithography process had excellent performance. Better contacts between the ZnO nanowire and metal electrodes could be improved through annealing and metal deposition using a focused ion beam.     

First-principles study on magnetism of different dimensional Ru systems

The magnetism, the magnetocrystalline anisotropy and the optical properties of the monolayer and atomic chain of 4d transition-metal Ru are investigated by using the full-potential linearized-augmented-plane-wave method in a generalized gradient approximation. The magnetic moments are 1.039~μ __B/atom and 1.130~μ_B/atom for the monolayer and atomic chain, respectively. Both systems have large magnetocrystalline anisotropy energy (MAE). The magnetic easy axis is normal to the monolayer and perpendicular to the chain axis in the atomic chain. The optical properties of the two low-dimensional Ru systems are investigated by calculating the complex optical conductivity tensor. Both systems exhibit anisotropy in photoconductivity, especially for the atomic chain. The physical origins of MAE and photoconductivity are studied based on electronic structures. It is found that the changes in crystal field caused by different symmetry-breaking mechanisms in the two low-dimensional Ru systems result in MAE through spin--orbit coupling, while the anisotropy in photoconductivity mainly comes from the crystallographic anisotropy.     

Novel material for nonvolatile ovonic unified memory (OUM)－Ag11In12Te26Sb51 phase change semiconductor

In this paper, Ag_{11}In_{12}Te_{26}Sb_{51} phase change semiconductor films have been prepared by dc sputtering. The crystallization behaviour of amorphous Ag_{11}In_{12}Te_{26}Sb_{51} thin films was investigated by using differential scanning calorimetry and x-ray diffraction. It was found that the crystallization temperature is about 483K and the melting temperature is 754.8K and the activation energy for crystallization, E_a, is 2.07eV. The crystalline Ag_{11}In_{12}Te_{26}Sb_{51} films were obtained using initializer. The initialization conditions have a great effect on the sheet resistance of Ag_{11}In_{12}Te_{26}Sb_{51} films. We found that the effect of the initialization condition on the sheet resistance can be ascribed to the crystallinity of Ag_{11}In_{12}Te_{26}Sb_{51} films. The sheet resistance of the amorphous (R_{amo}) film is found to be larger than 1×10^6Ω and that of the crystalline (R_{cry}) film lies in the range from about 10^3 to 10^4Ω. So we have the ratio R_{amo}/R_{cry}=10^2～10^3, which is sufficiently large for application in memory devices.     

State-to-state dynamics of reactions H+DH'(v=0,j=0)→HH'(v',j')+D/HD(v',j')+H'with time-dependent quantum wave packet method

State-to-state time-dependent quantum dynamics calculations have been carried out to study H+DH'→HH'+D/HD+H' reactions on BKMP2 surface.The total integral cross sections of both reactions are in good agreement with earlier theoretical and experimental results,moreover the rotational state-resolved reaction cross sections of H+DH'→HH‘+D at collision energy Ec=0.5 eV are closer to the experimental values than the ones calculated by Chao et al [J.Chem.Phys.117 8341(2002)],which proves the higher precision of the quantum calculation in this work.In addition,the state-to-state dynamics of H+DH'→ HD'+H reaction channel have been discussed in detail,and the differences of the micro-mechanism of the two reaction channels have been revealed and analyzed clearly.     

Deposition and characterization of YBCO/CeO2/YSZ/CeO2 multilayers on biaxially textured Ni substrates

CeO2/YSZ/CeO2 buffer layers were deposited on biaxially textured Ni substrates by pulsed laser deposition. The influence of the processing parameters on the texture development of the seed layer CeO2 was investigated. Epitaxial films of YBCO were then grown in situ on the CeO2/YSZ （yttria-stabilized ZrO2）/CeO2-buffered Ni substrates. The resulting YBCO conductors exhibited self-fleld critical current density Jc of more than 1 MA/cm^2 at 77K and superconducting transition temperature Tc of about 91K.     

Growth and transport features of electron-doped superconductor Pr1-xLaCexCuO4-δ thin films

<正>T’-phase electron-doped superconductor Pr_1-xLaCe_xCuO_4-δ（PLCCO） thin films are successfully prepared on SrTiO₃（100） substrates by using the dc magnetron sputtering method.It is found that the films each have a highly oriented structure along the c-axis.For optimally doped films with x≈0.10,the superconducting transition temperature T_c is 23.5 K,which is similar to that of a single crystal.The quadratic temperature dependence of the resistivity is observed when T > T_c,which can be attributed to the two-dimensional Fermi liquid behaviour.Besides,the optimal conditions for preparing the T’-phase PLCCO thin films are also discussed in detail.     

Anomalous magnetic properties of an iron film system deposited on fracture surfaces of α-Al2O3 ceramics

An iron film percolation system is fabricated by vapour-phase deposition on fracture surfaces of α-Al2O3 ceramics. The zero-field-cooled （ZFC） and field-cooled （FC） magnetization measurement reveals that the magnetic phase of the film samples evolve from a high-temperature ferromagnetic state to a low-temperature spin-glass-like state, which is also demonstrated by the temperature-dependent ac susceptibility of the iron films. The temperature dependence of the exchange bias field He of the iron film exhibits a minimum peak around the temperature T=5 K, which is independent of the magnitude of the cooling field Hcf. However, for T 〉 10K, （1） He is always negative when Hcf=2kOe and （2） for Hcf= 20 kOe （1Oe≈80 A/m）, He changes from negative to positive values as T increases. Our experimental results show that the anomalous hysteresis properties mainly result from the oxide surfaces of the films with spin-glass-like phase.