(001)Si衬底上La0.9Sr0.1MnO3/SrTiO3外延生长薄膜的界面电子显微学研究

本文利用高分辨电子显微术、电子能量损失谱和电子全息技术对Si基体上生长的SrTiO3（STO）和La0.9Sr0.1MnO3（LSMO）薄膜及其STO层和Si基体之间的界面结构进行了深入研究，结果表明在Si和STO层之间由于氧扩散会形成一层过渡的SiOx无序层，且随沉积条件不同界面原子无序层厚度稍有不同；选区电子衍射结果表明薄膜和基体之间的外延生长关系为[001]LSMO//[^-110]Si，[110]LSMO//[001]Si[001]STO，//[001]Si，[010]STO//[110]Si；电子能量损失谱分析表明界面无序层中Si离子的氧化态处于Si^2＋和Si^0之间；电子全息结果清晰地显示了基体与薄膜之间存在明显的相位和势垒变化，负电荷聚集在界面SiOx的无序层中。     

庞磁电阻La0.8Sr0.2MnO3薄膜的微结构研究

利用激光分子束外延方法在(001)SrTiO3衬底上制备庞磁电阻La0.8Sr0.2MnO3薄膜.发现高密度、尺度均匀的纳米聚集物弥散地分布在La0.8Sr0.2MnO3薄膜中.Z衬度像、EDS及电子衍射综合分析表明,这些纳米聚集物的内部成分出现起伏,主要特征是富Mn贫La,Mn/La的比值在其核心处达到极大值,形成立方结构的第二相MnO.LSMO薄膜由两种正交结构的取向畴组成.MnO与畴1的取向关系为[101]LSMO,1//[100]MnO和(010)LSMO,1//(010)MnO;与畴2的关系为[101]LSMO,2//[100]MnO和(010)LSMO,2//(001)MnO.在LSMO/STO外延体系中,还观察到大量的失配位错.失配位错的类型分为刃型失配位错,位错线沿<100>方向;螺型失配位错,位错线沿<110>方向.刃型位错是基中原有位错在薄膜生长过程中沿生长表面的扩展造成的;螺型失配位错的形成与降温过程中LSMO正交结构的取向畴的形成有关.     

原位(TiB+TiC)/Ti复合材料中TiB/Ti界面的微结构研究

本文利用透射电镜（TEM）和高分辨透射电镜（HRTEM）研究了利用钛与碳化硼之间的自蔓燃高温合成反应,经普通的熔炼工艺制备的（TiB TiC)/Ti复合材料中TiB晶须与钛界面的微观组织结构。结果发现：界面非常洁净,两侧晶体存在如下平行关系：[010]TiB//[011^-0]Ti,(100)TiB//(2^-110)Ti,(001)TiB//(0002)Ti和[001]TiB//[011^-0]Ti,(010)TiB//(2^-110)Ti,(200)TiB//(0002)Ti。利用凝固理论分析了TiB/Ti界面微结构的形成机制,较好地解释了原位（TiB TiC)/Ti复合材料中TiB/Ti界面结合较好的原因。     

GaN在Si(001)上的ECR等离子体增强MOCVD直接生长研究

研究了用电子回旋共振(ECR)等离子体增强金属有机物化学气相沉积(PEMOCVD)技术在Si(001)衬底上,低温(620～720℃)下GaN薄膜的直接外延生长及晶相结构.高分辨透射电镜(HRTEM)和X射线衍射(XRD)结果表明:在Si(001)衬底上外延出了高度c轴取向纤锌矿结构的GaN膜,但在GaN/Si(001)界面处自然形成了一层非晶层,其两个表面平坦而陡峭,厚度均匀(≈2nm).分析认为,在初始成核阶段N与Si之间反应所产生的这层SixNy非晶层使GaN的β相没有形成.XRD和原子力显微镜(AFM)结果表明,衬底表面的原位氢等离子体清洗,GaN初始成核及后续生长条件对GaN膜的晶体质量非常重要.     

GaN在Si(001)上的ECR等离子体增强MOCVD直接生长研究

研究了用电子回旋共振(ECR)等离子体增强金属有机物化学气相沉积(PEMOCVD)技术在Si(001)衬底上,低温(620～720℃)下GaN薄膜的直接外延生长及晶相结构.高分辨透射电镜(HRTEM)和X射线衍射(XRD)结果表明:在Si(001)衬底上外延出了高度c轴取向纤锌矿结构的GaN膜,但在GaN/Si(001)界面处自然形成了一层非晶层,其两个表面平坦而陡峭,厚度均匀(≈2nm).分析认为,在初始成核阶段N与Si之间反应所产生的这层SixNy非晶层使GaN的β相没有形成.XRD和原子力显微镜(AFM)结果表明,衬底表面的原位氢等离子体清洗,GaN初始成核及后续生长条件对GaN膜的晶体质量非常重要.     

MBE生长中缓冲层对InSb/GaAs质量影响的研究

用分子束外延(MBE)方法在GaAs(001)衬底上外延生长了InSb薄膜,并研究了异质外延InSb薄膜生长中缓冲层对材料质量的影响.采用原子力显微镜(AFM)、透射电子显微镜(TEM)、X射线双晶衍射(DCXRD)等方法研究了InSb/GaAs薄膜的表面形貌、界面特性以及结晶质量.通过生长合适厚度的缓冲层,获得了室温下DCXRD半高峰宽为272",迁移率为64 300 cm2V-1s-1的InSb外延层.     

受控生长方法抑制PZNT铁电薄膜中焦绿石相的形成

用液相外廷方法在LaAlO3(001)、MgO(001)、SrTiO3(001)以及SrTiO3(001)/PZT(001)衬底上制备了PZNT薄膜.结果表明在LaAlO3,(001)村底上获得的PZNT薄膜的晶粒以三维岛状自发形式生长发育,而且薄膜中有大量的焦绿石异相晶粒存在;在MgO(001)和SrTiO3(100)衬底上,晶粒为三维岛状异质外廷生长,薄膜中焦绿石异相几乎消失;在SrTiO3(001)衬底引入(100)取向的PZT种膜后,膜中晶粒生长变为二维生长,获得了完整的PZNT膜,显著改善了外延膜的质量.分析了衬底取向对紧邻层纳米尺寸范围的晶粒形成、薄膜晶粒的发育、克服薄膜中异相形成等的影响.     

在(001)SrRuO_3/(001)SrTiO_3上外延生长c轴取向Bi_(3.15)Nd_(0.85)Ti_3O_(12)铁电薄膜的显微结构研究

用脉冲激光沉积在(001)SrRuO3,(001)SrTiO3上外延生长了c轴取向的Bi3.15Nd0.85Ti3O12(BNdT)铁电薄膜.SrRuO3底电极层厚约117 nm,BNdT薄膜厚～35nm.X射线衍射(XRD)和透射电镜(TEM)观察证实了SrRuO3层和BNdT薄膜的外延生长.通过TEM平面样品观察,在SrRuO3/BNdT界面附近看到了两种村度处于不同高度的失配位错网,位错线沿<110>走向,其柏格斯矢量沿[110]或[110]方向有分量,在[001]方向上可能没有分量.讨论了位错的形成机制.     

TiO2薄膜的相结构调控与表征

本文利用脉冲激光沉积技术在LaAlO3(001)衬底上生长了单晶锐钛矿和双相TiO2薄膜,并利用X射线衍射和透射电子显微术对薄膜的显微结构进行了系统表征.单晶锐钛矿薄膜在LaAlO3(001)衬底上实现了外延生长,双相TiO2薄膜以单晶锐钛矿TiO2为基体,在其中夹杂着金红石TiO2颗粒.TiO2薄膜的相结构可通过调整...     

脉冲激光沉积制备NiO(111)外延薄膜及其结构研究

采用脉冲激光沉积法(PLD)在具有六方纤锌矿结构的蓝宝石衬底上制备了NiO外延薄膜,研究了沉积温度、氧分压对薄膜结构和形貌的影响。在650℃、20Pa氧分压的条件下制得了高结晶质量的单晶NiO薄膜。高能电子衍射分析发现,该NiO薄膜沿Al2O3[11–20]方向入射的衍射图像为清晰的斑点,说明NiO薄膜的生长模式为岛状模式,薄膜与衬底的外延匹配关系为:(111)[11–2]NiO//(0001)[11–20]Al2O3。     

Structural and Electrical Characters of Ba0.6Sr0.4TiO3/La0.5Sr0.5CoO3 Thin Films by Plus Laser Deposition

Epitaxial Ba0.6Sr0.4TiO3 (BST) thin films were deposited on LaAlO3 (LAO) substrates with the conductive metallic oxide La0.5Sr0.5CoO3 (LSCO) film as a bottom electrode by pulsed laser deposition (PLD). X-ray diffraction ~2 and Ф scan showed that the epitaxial relationship of BST/LSCO/LAO was [001] BST//[001] LSCO//[001] LAO. The atomic force microscope (AFM) revealed a smooth and crack-free surface of BST films on LSCO-coated LAO substrate with the average grain size of 120 nm and the RMS of 1.564 nm for BST films. Pt/BST/LSCO capacitor was fabricated to perform CapacitanceVoltage measurement indicating good insulating characteristics. For epitaxial BST film, the dielectric constant and dielectric loss were determined as 471 and 0.03, respectively. The tunabilty was 79.59% and the leakage current was 2.6310-7 A/cm2 under an applied filed of 200 kV/cm. Furthermore, it was found that epitaxial BST (60/40) films demonstrate well-behaved ferroelectric properties with the remnate polarization of 6.085 C/cm2 and the coercive field of 72 kV/cm. The different electric properties from bulk BST (60/40) materials with intrinsic paraelectric characteristic are attributed to the interface effects.     

Mo基底的粗糙度对C轴择优取向AlN的影响

通过物理气相沉积的方法制备出Si／非晶／Mo／AlN多层膜器件,利用透射电子显微学方法研究了截面样品和AlN薄膜平面样品,确定了AlN和 Mo的界面形态和生长方式。研究表明二者取向关系为[2110] AlN／／[111]Mo,（0002）AlN／／（110）Mo,且Mo表面的粗糙程度对AlN的生长有影响,因此本文为改进器件性能提供了参考方向。     

Structural and Electrical Characters of Ba0.6Sro.4TiO3/La0.5Sr0.5CoO3 Thin Films by Plus Laser Deposition

Epitaxial Ba0.6Sr0.4TiO3 (BST) thin films were deposited on LaAlO3 (LAO) substrates with the conductive metallic oxide La0.5Sr0.5CoO3 (LSCO) film as a bottom electrode by pulsed laser deposition (PLD). Xray relationship of BST/LSCO/LAO was [001] BST//[001]LSCO//[001] LAO. The atomic force microscope (AFM)revealed a smooth and crackfree surface of BST films on LSCOcoated LAO substrate with the average grain size of 120 nm and the RMS of 1.564 nm for BST films.Pt/BST/LSCO capacitor was fabricated to perform CapacitanceVoltage measurement indicating good insulating characteristics. For epitaxial BST film, the dielectric constant and dielectric loss were determined as 471 and 0.03, respectively. The tunabilty was 79.59% and the leakage current was 2.63×107 A/crm2 under an applied filed of 200 kV/cm. Furthermore, it was found that epitaxial BST (60/40) films demonstrate wellbehaved ferroelectric properties with the remnate polarization of 6.085 μC/cm2 and the coercive field of 72 kV/cm. The different electric properties from bulk BST (60/40)materials with intrinsic paraelectric characteristic are attributed to the interface effects.     

Interfacial reactions of cobalt thin films on (001) GaAs

Interfacial reactions between cobalt thin films and (001) GaAs have been studied by transmission electron microscopy, energy-dispersive analysis of x-rays in a scanningTEM, Auger electron spectroscopy and x-ray photoelectron spectroscopy. The completely reacted layer was found to be “β-Ga₂0₃/(CoGa, CoAs)/GaAs.” The formation of a surface layer ofβ-Ga₂O₃ and the use of encapsulated samples minimized As loss from the reacted layer. Both CoGa and CoAs were found to grow epitaxially on (001) GaAs. The orientation relationships between CoGa and GaAs were determined to be [001] CoGa//[001] GaAs and (220) CoGa//(220) GaAs. The Burgers vectors of interfacial dislocations were identified as 1/2 〈101〉 and 1/2 〈011〉 which are inclined to the (001) GaAs surface. Almost all of the CoGa films were found to be epitaxially related to the surface. No interfacial dislocations were observed in most of the epitaxial CoAs films which are considered to be pseudomorphic with respect to GaAs. The orientation relationships between CoAs and GaAs were determined to be [101] CoAs//[011] GaAs and (020) CoAs//(220) GaAs. Two-step annealing was found to be effective in promoting epitaxial growth.     

Low Fatigue in Epitaxial Pb(Zr<Subscript>0.2</Subscript>Ti<Subscript>0.8</Subscript>)O<Subscript>3</Subscript> on Si Substrates with LaNiO<Subscript>3</Subscript> Electrodes by RF Sputtering

Epitaxial PZT (001) thin films with a LaNiO₃ bottom electrode were deposited by radio-frequency (RF) sputtering onto Si(001) single-crystal substrates with SrTiO₃/TiN buffer layers. Pb(Zr_0.2Ti_0.8)O₃ (PZT) samples were shown to consist of a single perovskite phase and to have an (001) orientation. The orientation relationship was determined to be PZT(001)[110]∥LaNiO₃(001)[110]∥SrTiO₃ (001)[110]∥TiN(001)[110]∥Si(001)[110]. Atomic force microscope (AFM) measurements showed the PZT films to have smooth surfaces with a roughness of 1.15 nm. The microstructure of the multilayer was studied using transmission electron microscopy (TEM). Electrical measurements were conducted using both Pt and LaNiO₃ as top electrodes. The measured remanent polarization P _r and coercive field E _c of the PZT thin film with Pt top electrodes were 23 μC/cm² and 75 kV/cm, and were 25 μC/cm² and 60 kV/cm for the PZT film with LaNiO₃ top electrodes. No obvious fatigue after 10¹⁰ switching cycles indicated good electrical endurance of the PZT films using LaNiO₃ electrodes, compared with the PZT film with Pt top electrodes showing a significant polarization loss after 10⁸ cycles. These PZT films with LaNiO₃ electrodes could be potential recording media for probe-based high-density data storage.     

准分子激光扫描淀积PZT/YBCO结构铁电薄膜

利用脉冲准分子激光（工作气体ＸｅＣｌ，波长３０８ｎｍ，脉宽２８ｎｓ）在外延ＹＢＣＯ／ＬａＡｌＯ３（１００）单晶基片上淀积了Ｐｂ（Ｚｒ０．５５Ｔｉ０．４５）Ｏ３铁电薄膜，ＹＢＣＯ薄膜既为生长高取向ＰＺＴ薄膜提供了晶体匹配条件，同时也为ＰＺＴ铁电薄膜提供了下电极。讨论了工艺参数对晶相结构和表面形貌的影响。用Ｘ射线衍射表征了该多层膜的晶相结构，扫描电镜观察其表面形貌。ＰＺＴ铁电薄膜的剩余极化为２１μＣ／ｃｍ２，矫顽场为６５ｋＶ／ｃｍ。     

UHV/CVD生长SiGe/Si异质结构材料

以 Si2 H6 和 Ge H4 作为源气体 ,用 UHV/CVD方法在 Si( 1 0 0 )衬底上生长了 Si1- x Gex 合金材料和 Si1- x Gex/Si多量子阱结构 .用原子力显微镜、X光双晶衍射和透射电子显微镜对样品的表面形貌、均匀性、晶格质量、界面质量等进行了研究 .结果表明样品的表面平整光滑 ,平均粗糙度为 1 .2 nm;整个外延片各处的晶体质量都比较好 ,各处生长速率平均偏差为 3.31 % ,合金组分 x值的平均偏差为 2 .0 1 % ;Si1- x Gex/Si多量子阱材料的 X光双晶衍射曲线中不仅存在多级卫星峰 ,而且在卫星峰之间观察到了 Pendellosung条纹 ,表明晶格质量和界面质量都很好 ;Si