AFM Studies of Platinum Silicide Thin Films on Silicon Grown by Pulsed Laser Deposition

PtSi ultra-thin films were grown on Si-wafer using pulsed laser deposition(PLD).The surface structure of these films was studied by atomic force microscopy(AFM).In addition ,the compositional structure of the PtSi as deter-mined from X-ray photoelectron spectroscopy(XPS)is discussed.First report of a possible growth mechanism is presented, on studying the variation of morphological features(i,e,roughness and size of crystallites)with annealing temperatures and the film thicknesses..     

脉冲激光制备硅基超薄PtSi薄膜

用脉冲激光沉制备了纳米级Pt/Si异质层,对激光退火形成超薄PtSi薄膜进行了研究,对于Pt、Si互扩散反应形成Pt2Si和PtSi的过程利用XPS进行了测试分析,通过XPS和AFM等分析测试手段对不同参数激光退火形成的PtSi薄膜的结构特性进行观测。我们获得了均匀的、超薄边疆的PtSi层且具有平滑的PtSi/Si界面。     

Effect of Annealing Temperature on the Formation of Silicides and the Surface Morphologies of PtSi Films

The effect of annealing temperature on the formation of the PtSi phase. distribution of silicides and the surface morphologies of silicides films is investigated by XPS. AFM. It is shown that the phase sequences of the films change from Pt-Pt2Si-PtSi-Si to Pt+Pt2Si+PtSi-PtSi-Si or Pt+Pt2Si+PtSi-PtSi-st with an increase of annealing temperature and the reason for the formation of mixed layers is discussed.     

Interface structure and electrical properties of PtSi/Si1−x Ge x diodes based on silicon

PtSi/strained Si_1–x Ge _x (x=0, 0.2, and 0.25) Schottky-barrier diodes (SBD) with extended cutoff wavelengths have been demonstrated by combining pulsed laser deposition (PLD) and molecular beam epitaxy (MBE). Pt was deposited by PLD on the Si_1–x Ge _x alloys with a thin Si sacrificial cap layer fabricated by MBE. By the reaction of deposited Pt film on Si, a sacrificial cap layer silicide SBD has been fabricated. Auger electron depth profiling was performed on the films before and after in vacuo annealing to study the redistribution of composition in the reactions. High-resolution transmission electron microscopy was used to investigate the interface structure. We have found that Pt reacts mainly with Si to form silicides at 350 °C, leaving some Ge to segregate at the surface. With annealing at 600 °C for 3 min the interface of PtSi/Si_1–x Ge _x is smooth. Since lowered-barrier-height silicide SBD are desirable for obtaining longer cutoff wavelength Si-based infrared detectors, the Schottky barrier heights of the PtSi/strained Si_1–x Ge _x SBDs with smooth interfaces were substantially lower than those of PtSi/Si SBDs, i.e., decreased with increasing Ge fraction, allowing for tuning of the SBDs cutoff wavelength. At 293 K, the ideality factor has been found to be 2.00 and 1.32 for PtSi/Si_0.80Ge_0.20 and PtSi/Si_0.75Ge_0.25 diodes, respectively. We have shown that high quantum efficiency and near-ideal dark current can be obtained in the film of PtSi/strained Si_1–x Ge _x with an excellent interface fabricated by MBE and PLD, after annealing at 600 °C for 3 min.     

硅基PtSi纳米薄膜制备及应用研究进展

PtSi红外探测器是一种重要的光电器件，在军事和民用方面均起着非常重要的作用。高质量硅基PtSi薄膜的制备是基础。本文介绍了溅射、分子束外延、脉冲激光沉积和激光分子束外延等制备PtSi薄膜的方法。并评述了PtSi红外探测器的最新应用研究进展及发展趋势。     

PLD法制备ZnO/Si异质结的I-V特性研究

用脉冲激光沉积法分别在不同电阻率的p型和n型Si( 100)衬底上制备了不掺杂ZnO薄膜,相应制成n-ZnO/p-Si和n-ZnO/n-Si异质结器件.利用X射线衍射和原子力显微镜对ZnO薄膜进行的结构和形貌测试表明,薄膜结晶情况良好,具有高度的c轴择优取向,表面颗粒大小、分布均匀.对器件的I-V特性测试表明,在无光条件下,制备的n-ZnO/p-Si异质结漏电流很低,而n-ZnO/n-Si同型异质结漏电流要稍大一些;随衬底电阻率的增大,上述器件的阈值电压变小;器件在光照下的漏电流明显比无光条件下的要大.     

Effect of annealing temperature on the tribological behavior of ZnO films prepared by sol-gel method

The tribological behavior of zinc oxide (ZnO) films grown on glass and silicon (100) substrates by sol-gel method was investigated. Particularly, the as-coated films were post-annealed at different temperatures in air to investigate the effect of annealing temperature. Crystal structural and surface morphology of the films were measured by X-ray diffraction (XRD) and Atomic Force Microscopy (AFM). XRD patterns and AFM images indicated that the crystallinity and grain size of the films were enhanced and increased, respectively, with temperature. The tribological behavior of films was evaluated by sliding the ZnO films against a Si₃N₄ ball under 0.5 gf normal load using a reciprocating pin-on-plate tribo-tester. The wear tracks of the films were measured by AFM to quantify the wear resistance of the films. The results showed that the wear resistance of the films could be improved by the annealing process. The wear resistance of the films generally increased with annealing temperature. Specifically, the wear resistance of the films was significantly improved when the annealing temperature was higher than 550° C. The increase in the wear resistance is attributed to the increase in hardness and modulus of the film with annealing temperature.     

Ti/La_(0.7)Ca_(0.3)MnO_3/Pt结构器件中“负”电阻开关特性研究

以Pt/Ti/SiO2/Si为衬底,制备了具有电阻转变特性的Ti/La0.7Ca0.3MnO3(LCMO)/Pt结构器件.X射线衍射分析表明LCMO薄膜呈纳米晶或非晶态,扫描电子显微镜及原子力显微镜分析表明LCMO薄膜表面平整、光滑致密.电学测试结果表明Ti/LCMO/Pt结构具有明显的双极型"负"电阻转变特性,低电阻态的导电过程为空间电荷限制电流机制,高电阻态的导电过程为Poole-Frenkel发射机制.利用氧化还原反应的随机性和TiOx中间层空间分布的不均匀性,定性地解释了高电阻态的不稳定性以及电流-电压曲线上的电流突变现象.     

红外用超薄PtSi膜的一种制备新方法

膜厚制约着PtSi红外探测器的量子效率。本文介绍了一种根据固相反应理论 ,在 1 0 - 4 Pa量级真空度条件下 ,采用真空退火、化学腐蚀手段制备超薄 (约 5 5nm)PtSi膜的新工艺方法 ,并用XRD ,XPS对所制备的样品进行了物相分析。该方法所需温度低 ,时间短 ,制得薄膜均匀性好     

Epitaxial growth of anatase TiO2 thin films on LaAlO3(100) prepared using pulsed laser deposition

Titanium dioxide thin films were grown on a lattice-matched LaAlO₃(100) surfaces using pulsed laser deposition (PLD) in oxygen atmosphere. The films were characterized using X-ray diffraction (XRD), reflection high-energy electron diffraction (RHEED) and atomic force microscopy (AFM). The crystal structure of all the films was anatase. Preferred oriented films with a c-axis normal to the substrate surface were obtained. RHEED analysis also revealed that the films had the preferential in-plane orientation, demonstrating that anatase films were epitaxially grown on the substrate. The flatness of the films depended on their growth conditions and thickness.     

Achieve 2-inch-diameter homogeneous GaN films on sapphire substrates by pulsed laser deposition

The 2-inch-diameter homogeneous GaN films have been epitaxially grown on sapphire substrates by pulsed laser deposition (PLD) technique with optimized laser rastering and PLD growth conditions. The as-grown GaN films are characterized by in situ reflection high-energy electron diffraction, white-light interferometry, scanning electron microscopy, atomic force microscopy (AFM), grazing incidence angle X-ray reflectivity, reciprocal space mappings, and micro-Raman spectroscopy for surface morphologies and structural properties. The as-grown 2-inch-diameter single-crystalline GaN films exhibit excellent thickness uniformity with a root-mean-square (RMS) inhomogeneity less than 3.4 % and very smooth surface with a RMS roughness less than 1.3 nm measured by AFM. There is a maximum of 1.2 nm thick interfacial layer existing between the as-grown GaN films and sapphire substrates, and the as-grown 310 nm thick GaN films are almost fully relaxed only with an in-plane compressive strain of 0.044 %. This work demonstrates a possibility for achieving high-quality large-scale GaN films with uniform thickness and atomically abrupt interface by PLD, and is of great interest for the commercial development of GaN-based optoelectronic devices.     

纳米级PtSi/P-Si(100)薄膜形成工艺研究

用XRD、XPS、TEM分析手段研究了在P－Si(100)上溅射的Pt膜,经不同工艺形成PtSi薄膜的物相及连续性。通过分析硅衬底预处理以及退火条件、气氛等对成膜质量的影响,找到形成超薄PtSi膜的工艺方法,制备出4nm连续薄膜。     

Growth of β-FeSi2 thin films on silicon (100) substrate for different annealing times by pulsed laser deposition

Single-phase β-FeSi₂ films were fabricated on silicon (100) substrates by pulsed laser deposition (PLD) technique and post-annealing process. The X-ray diffraction (XRD) showed that the diffraction intensity reached a certain threshold and then decreased with the increase of annealing time. The scanning electron microscopy (SEM) observations revealed surface morphologies of the films for different annealing times. The optimal photoluminescence (PL) of the films was obtained after 9 h annealing process. Based upon all the experimental results, it was found that the luminous properties were associated with the crystalline quality and surface morphologies.     

ZnTe:Cu多晶薄膜结构和电性质

用共蒸发法在室温下制备了ZnTe：Cu多晶薄膜,利用XRD、AFM和XPS等测试技术对样品进行了表征,研究了掺Cu浓度和退火温度对薄膜物相和晶粒度的影响,分析了薄膜表面的元素状态。根据铜离子的变价行为对异常的电阻率温度关系作了解释。并确定了最佳掺铜浓度和退火温度。     

新型溶胶-凝胶法制备纳米MgO薄膜的研究

以硝酸镁为起始原料,胶棉液为添加剂,在Ｓｉ（１００）衬底上成功地制备ＭｇＯ薄膜,结果表明,胶棉液是形成ＭｇＯ溶胶的关键组份;薄膜的晶体结构与胶棉液的含量及退火温度有关．同时,用Ｘ射线衍射（ＸＲＤ）、原子力显微镜（ＡＦＭ）和透射电镜（ＴＥＭ）对薄膜的微观结构进行了分析．     

新型溶胶-凝胶法制备纳米MgO薄膜的研究

以硝酸镁为起始原料,胶棉液为添加剂,在Ｓｉ（１００）衬底上成功地制备ＭｇＯ薄膜,结果表明,胶棉液是形成ＭｇＯ溶胶的关键组份;薄膜的晶体结构与胶棉液的含量及退火温度有关．同时,用Ｘ射线衍射（ＸＲＤ）、原子力显微镜（ＡＦＭ）和透射电镜（ＴＥＭ）对薄膜的微观结构进行了分析．     

Thermal stability of sputtered zirconium oxide films

In this work, the effect of post-growth annealing on the structural and optical properties of sputtered zirconium oxide films has been investigated. The temperature dependence of structure, density, and optical constants has been systematically studied by X-ray diffraction, X-ray reflectometry, atomic force microscopy (AFM) and optical spectroscopy. X-ray diffraction studies show no variation in the crystalline phase upon annealing except grain growth. X-ray reflectivity measurements determine a density increase of approximately 11% and a simultaneous thickness reduction of 10% upon annealing. The surface roughness of the films increases upon annealing as determined by XRR and confirmed by AFM measurements. Optical spectroscopy measurements confirm that the refractive index n of the films decreases with increasing annealing temperature. At the same time the optical band gap E_g of the films increases from 4.58 to 4.97 eV annealing at 900°C. The surprising decrease of refractive index upon annealing is attributed to both the intermixing of Si with ZrO₂ and the increasing surface roughness of the films.     

溶胶-凝胶法制备MgO薄膜的研究

本文采用非金属醇盐以醋酸镁为起始原料,胶棉液为添加剂,在Ｓｉ（１００） 衬底上成功地制备了ＭｇＯ 薄膜。结果表明,薄膜的晶体结构与胶棉液的含量及退火温度有关。同时,用Ｘ射线衍射（ ＸＲＤ） 、原子力显微电镜（ＡＦＭ） 和透射电镜（ ＴＥＭ） 对薄膜的微观结构进行了分析。这种制备ＭｇＯ 薄膜的新方法还未见有报道。     

Structural and magnetic properties of GaN:Sm:Eu films fabricated by co-implantation method

Diluted-magnetic GaN:Sm:Eu films have been fabricated by co-implantation of Sm and Eu ions into c-plane(0001) GaN films and a subsequent annealing process. The structural, morphological and magnetic characteristics of the samples have been investigated by means of high-resolution X-ray diffraction (HRXRD), atomic force microscopy (AFM), and superconducting quantum interference device (SQUID). The XRD and AFM analyses show that the annealing process can effectively recover the crystalline degradation caused by implantation. Compared with GaN:Sm films, more defects have been introduced into GaN:Sm:Eu films due to the Eu implantation process. According to the SQUID analysis, GaN:Sm:Eu films exhibit clear room-temperature ferromagnetism. Moreover, GaN:Sm:Eu films show a lower saturation magnetization (Ms) than GaN:Sm films.     

Optical study of Mn-doped Bi4Ti3O,12 thin films by spectroscopic ellipsometry

Mn-doped Bi4Ti3O12(B4T3) thin films grown at 400 degrees C on a Pt/Ti/SiO2/Si substrate through pulsed laser deposition (PLD) were analyzed via spectroscopic ellipsometry (SE). The PLD targets were produced through the conventional solid-state sintering method, and the film samples were annealed at 600 degrees C. The SE spectra of B4T3 films were measured using a rotating analyzer type ellipsometer within the 1.12 to 6.52 eV energy range, with the various incidence angles. The optical properties of the B4T3 films with increasing Mn-mol concentration were extracted using a multilayer model for the whole structure and the Tauc-Lorentz (TL) dispersion relation for the B4T3 film layer. The analysis results clearly showed that the significant changes in optical properties of B4T3 films are caused by thermal annealing procedure and the Mn-mol concentrations. X-ray diffraction (XRD) measurement was also performed to confirm the results of SE analysis.