RBS和XRD研究Fe、N共掺ZnO薄膜的制备

以Zn3N2:Fe为前驱物,用热氧化法在石英玻璃衬底上成功制备了一组Fe、N共掺杂的ZnO薄膜。用卢瑟福背散射(RBS)和X射线衍射(XRD)研究了Zn3N2:Fe在不同热氧化温度下的退火行为和结构演变。实验结果显示:刚长成的样品为Zn3N2:Fe薄膜;300oC氧化后,样品表层的Zn3N2:Fe转化为ZnO:(Fe,N),表层以下的膜层未被氧化;退火温度高于400oC时,Zn3N2:Fe薄膜全部转化为多晶结构的ZnO:(Fe,N)薄膜;500oC退火,薄膜开始向衬底扩散;600oC–700oC退火,薄膜向衬底扩散明显。在XRD灵敏度范围内,薄膜中未发现Fe团簇或与Fe相关的二次相(如Fe3O4、Fe2O3、FeO)。SQUID测量显示:在500oC退火条件下,ZnO:(Fe,N)薄膜的室温饱和磁化强度(Ms)最大。     

分子束外延生长ZnO薄膜及性能研究

用分子束外延（MBE）和氧气氛方法，并改变束源炉和衬底生长温度，在Si(100)衬底上，采用Zn作缓冲层以解决ZnO层与衬底间的晶格失配问题，生长得到ZnO薄膜。在ZnO/Zn/Si(100)薄膜样品的X射线衍射（XRD）谱中，观测到ZnO的（100）、（200）、（101）和（103）等衍射峰；用原子力显微镜（AFM）观测ZnO薄膜的表面形貌，为直径约80－90mm的量子点，表明已得到具有纳米结构的ZnO薄膜。用同步辐射EXAFS技术研究了ZnO薄膜的局域结构，得到有关的几个结构参数。     

分子束外延生长ZnO薄膜的XAFS研究

利用同步辐射广延X射线吸收精细结构(EXAFS),研究在不同条件下分子束外延制备的ZnO薄膜,如分别在蓝宝石(0001)、Si(100)衬底上,生长温度为200℃或300℃下得到样品的局域结构。发现这些ZnO薄膜的EXAFS函数(k^2x(k))谱形状相似,说明各个样品都具有较为相近的基本局域结构。对生长温度为200℃的ZnO／Al2O3(0001)和ZnO／Si(100)样品,其Zn-O第一配位峰的无序度仃。分别为0．0054A^2和0．0080A^2,当生长温度从200℃提高到300℃时,ZnO／Al2O3(0001)样品的Zn-O第一配位峰的无序度仃。降为0．0039A^2。结果表明衬底与ZnO的晶格失配度和生长温度对ZnO薄膜的配位数、Zn-O键长影响不大,但较小的晶格失配度和较高的生长温度下得到的ZnO薄膜局域有序性较高;且样品的局域结构越有序,相应的配位峰幅度也越高。     

X射线吸收光谱技术中的滤光片研制

在同步辐射X射线吸收光谱(XAS)实验中,X射线滤光片用于吸收样品的康普顿散射和弹性散射,改善荧光信号的质量。我们将ZnO颗粒分散在聚氨酯溶液里,通过恰当的喷涂工艺,获得ZnO滤片。X射线衍射(XRD),X射线荧光(XRF)及X射线吸收光谱(XAS)实验结果表明：在滤片制备过程中,ZnO结构保持不变。进一步地,ZnO滤片用于测量Ga2O3的GaK边XAS谱,显示出好的信噪比。采用同样的方法还制备了其它X射线滤光片,表明这种X射线滤光片制备技术的可行性和实用性。     

YBa2Cu3O7—x／La2／3Ca1／3MnO3异质结构薄膜的微结构

本通过高分辨X射线衍射及掠入射(GID)的实验方法对生长在SrTiO3衬底上的LLa2/3Ca1/3MnO3和YBaCu3O7单层膜及YBa2Cu3O7-x/La2／3Ca1／3MnO3异质结构双层薄膜的微结构进行了研究。结果发现,所有薄膜都呈c向生长。由于热膨胀系数的不同而引起的热应力使得LCMO膜的晶格参数与靶材的相差较大。La2/3Ca1/3MnO3在单层腹及双层膜中都由靶材的立方结构变成了薄膜状态的四方结构。YBa2Cu3O7在单层膜及双层膜中都由靶材的正交结构变成了薄膜状态的四方结构。La2/3Ca1/3MnO3膜与YBa2Cu3O7膜在不同的样品中处于不同的应力状态。     

ZnO/α-Al_2O_3界面结构的掠入射X射线衍射研究

采用脉冲激光沉积(PLD)技术,以α-Al2O3(001)为衬底,在不同衬底温度下制备ZnO薄膜.利用X射线衍射(XRD)和同步辐射掠入射x射线衍射(GID)研究了薄膜的结晶性能和薄膜与衬底的界面结构.实验结果表明,在衬底温度较低(450℃)时,ZnO薄膜主要受衬底拉应力的作用,使界面处a方向的晶格常数增大;而在衬底温度较高(750℃)时,ZnO薄膜主要受衬底压应力的作用,使界面处a方向的晶格常数减小;在优化的衬底温度(650℃)下,ZnO薄膜受到的衬底应力较小,结晶性最好.且ZnO薄膜垂直方向的晶格排列要比面内的晶格排列更有序.     

La0.7Ca0.3MnO3薄膜的掠入射X射线衍射研究

利用90°离轴射频磁控溅射方法将Lao.7Ca0.3MnO3(LCMO)沉积于(001)取向的SrTiO3(STO)、MgO和α-Al2O3(ALO)单晶基片上,薄膜厚度均为500 A.通过掠入射X射线衍射技术测量了LCMO薄膜的横向晶格常数(即面内晶格常数),结合常规X射线衍射研究了LCMO薄膜的晶格应变及其弛豫情况.结果表明,LCMO薄膜在MgO和ALO基片上的应变弛豫临界厚度很小,这可能与薄膜-基片之间高的晶格失配率有关.LCMO薄膜的应变弛豫与四方畸变的弛豫可能具有不同的机制.利用掠入射X射线衍射对LCMO薄膜面内生长取向的研究给出了与利用电子显微技术研究相同的结果.     

Pr_(1-x)Sr_xMnO_3体系中O2p空穴参与的xO1s近边吸收谱

对于 Pr1- SrxMnO3 体系 x = 0 和 0.3 以及 MnO2 在 O K 边进行了 X 射线吸收谱实验研究。在 x = 0 的 xPrMnO3 端点化合物进行空穴掺杂使 x = 0.3,当体系成为 Pr0.7Sr0.3MnO3 时,实验结果显示其在 Mn 3d 轨道上的电子数目并不随空穴掺杂减少,反而有增加的趋势。对该结果基于 O 2p 与 Mn 3d 轨道的杂化和共价键特性进行了探讨。     

PZT薄膜的晶格常数与其厚度的关系

对磁控溅射法在YBa2Cu3O7-δ缓冲层及SrTiO3(001）衬底上生长的Pb(Zr0.52Ti0.48）O3薄膜材料，应用X射线散射倒空间作图法研究了薄膜在垂直（a⊥）和平行（a||）于表面方向的晶格常数与其厚度的关系。研究结果表明，随着PZT厚度的增加，a⊥增加，而a||减小。这种晶格常数的变化，不能用一般的薄膜弹性畸变来解释，我们归结为晶体的尺寸效应起了很大的作用。X射线衍射的测量结果表明，随着PZT厚度的增加，其晶粒尺寸也增加。     

中频磁控溅射制备GaN薄膜

采用中频磁控溅射技术,以金属Ga为靶材料,在si(111)衬底上形成了GaN薄膜,研究了溅射压强、衬底温度等对GaN薄膜结构和成分的影响.发现沉积气压为0.4～1.0 Pa时,薄膜呈GaN(002)取向,气压大于1.0 Pa和小于0.4 Pa时,用X射线衍射方法难以观察到GaN(002)的衍射峰.X射线能谱分析表明在最佳实验条件下制备的GaN薄膜的元素比Ga∶N为1∶1.     

EXAFS and SR-XRD study on Mn occupations in Zn1−xMnxO diluted magnetic semiconductors

Mn-doped ZnO films were prepared by radio frequency (RF) magnetron sputtering on sapphire substrate. Mn content was determined by proton induced X-ray emission (PIXE). Only Mn, no other magnetic impurities such as Fe, Co and Ni were observed. Also, no precipitates such as MnO, Mn₃O₄ and other secondary phases or Mn clusters, were found by SR-XRD, even in Mn-doped content up to 11 at.%. EXAFS analyses showed that Mn atoms were incorporated into ZnO crystal lattice by occupying the sites of zinc atoms.     

EXAFS and SR-XRD study on Cu occupation sites in Zn1-xCuxO diluted magnetic semiconductors

ZnO films, doped with 2.9 atom% Cu, were prepared by radio frequency magnetron sputtering on sapphire substrate at different substrate temperatures. No magnetic impurities such as Fe, Co and Ni were found in the PIXE spectra. The ZnO:Cu films possessed the wurtzite ZnO structure. No precipitates such as CuO and Cu2O or Cu cluster, were observed by synchrotron radiation X-ray diffraction in the ZnO:Cu films. Extended X-ray absorption fine structure (EXAFS) analysis showed that Cu atoms were incorporated into ZnO crystal lattice by occupying the sites of Zn atoms.     

ZnO thin films deposited by capillaritron ion beam sputtering deposition

ZnO thin films were deposited by capillaritron ion beam sputtering deposition. The crystalline quality, stoichiometry and photoluminescence properties of as-deposited and annealed ZnO thin films were studied. The as-deposited ZnO films show no preferred crystallographic orientations while annealed films exhibit a strong single ZnO (0 0 2) diffraction peak at 34.50°. The stoichiometry of ZnO films were found to be dependent on both beam energy and annealing conditions that the atomic percent ratio of Zn/O can be controlled between 0.95 and 1.10. ZnO films deposited with 4 keV ion beam and annealed at 800 °C in oxygen shows the lowest defect related deep level visible emission, while 80% of oxygen atoms are still located in fully oxidized stoichiometric ZnO matrixes.     

EDXRF法直接测定铁氧体中MnO,ZnO和Fe2O3的含量

用ＥＤＸＲＦ法直接测定锰锌铁氧体中ＭｎＯ、ＺｎＯ和Ｆｅ２Ｏ３含量是采用软、硬件相结合的办法，成功地分解ＭｉｌＫ和ＦｅＫ重迭峰，并对特定基体效应提出具体对策。由２３８Ｐｕ同位素源和正比计数管组成的探测系统，对ＭｎＯ、ＺｎＯ和Ｆｅ２Ｏ３的测量准确度分别为０．１４％、０．１０％和０．１７％。     

Structural distortion effect in the cobalt ions implanted TiO2 films

TiO₂ thin films were prepared by direct current magnetron sputtering on glass substrates, then were implanted by cobalt ions, and finally annealed at 400 and 500 °C for 50 min, respectively. They were identified as an anatase structure by X-ray diffraction (XRD). Scanning electron microscope (SEM) images showed that the grain sizes of the films grow with increasing annealing temperature. The energy dispersive X-ray (EDX) measurements indicated that the ratio of the cobalt atoms number and total atoms number of cobalt and titanium in the Co-TiO₂ films was about 2.51%, and X-ray photoelectron spectroscopy (XPS) results revealed that the cobalt existed in the films as Co²⁺. The element distribution of cobalt along cross-section of the films was studied by EDX, as the results showed that the cobalt diffused deeply into the films after annealing. The high resolution transmission electron microscopy (HRTEM) images were used to affirm the anatase structure of the Co-TiO₂ films, and edge dislocations were further found in the HRTEM images, which could be attributed to the effect of the implantation.     

Growth, characterization and effect of substrate bias on ZnO prepared by reactive capillaritron ion beam sputtering deposition

ZnO thin films have been deposited on Si substrates by reactive ion beam sputtering deposition utilizing a capillaritron ion source. All the as-deposited ZnO films exhibit a preferred (0 0 2) growth direction while the grain size increases as oxygen partial flow rate increases. An optimum photoluminescence result was achieved using oxygen partial flow rate of ∼40% that the ratio of integrated deep level emission to that of integrated near-band-edge emission is less than 1.5. The atomic percentage ratio of Zn:O remains at 55/45, regardless of oxygen partial flow rates. With the applied substrate bias, the atomic percentage ratio of Zn/O changes to 40/60, indicating that stoichiometric ZnO may be achieved by selecting appropriate substrate bias. With the substrate bias applied, increased amount of oxygen atoms were found located in oxygen deficient matrixes, likely due to the bombardment of secondary ions.     

X-ray absorption spectroscopy and X-ray photoelectron spectroscopy studies of CaSO4:Dy thermoluminescent phosphors

Extended X-ray absorption fine structure (EXAFS) measurements have been carried out on CaSO₄:Dy phosphor samples at the Dy L₃ edge with synchrotron radiation. Measurements were carried out on a set of samples which were subjected to post-preparation annealing at different temperatures and for different cycles. The EXAFS data have been analysed to find the Dy-S and Dy-O bond lengths in the neighbourhood of the Dy atoms in a CaSO₄ matrix. The observations from EXAFS measurements were verified with XANES and XPS techniques. On the basis of these measurements, efforts were made to explain the loss of thermoluminescence sensitivity of CaSO₄:Dy phosphors after repeated cycles of annealing at 400 °C in air for 1 h.     

The low temperature growth of stable p-type ZnO films in HiPIMS

In this study,the influence of substrate temperature on properties of A1-N co-doped p-type ZnO films is explored.Benefitting from the high ionization rate in high-power impulsed magnetron sputtering,the concentration of ionized nitrogen N+ and ionized zinc Zn+ were increased,which promoted the formation of ZnO films and lowered the necessary substrate temperature.After optimization,a co-doped p-type ZnO thin film with a resistivity lower than 0.35 Ω cm and a hole concentration higher than 5.34 × 1018 cm-3 is grown at 280 ℃.X-ray diffraction results confirm that A1-N co-doping does not destruct the ZnO wurtzite structure.X-ray photoelectron spectroscopy demonstrates that the presence of A1 promotes the formation of acceptor (No)defects in ZnO films,and ensures the role of A1 in stabilizing p-type ZnO.