含NiTi阻挡层的硅基(La0.5Sr0.5)CoO3/Pb(Zr0.4Ti0.6)O3/(La0.5Sr0.5)CoO3铁电电容器异质结

应用磁控溅射法制备的非晶NiTi薄膜作阻挡层,在Si (100)衬底上构造了(La0.5Sr0.5)CoO3/ Pb(Zr0.4Ti0.6)O3/(La0.5Sr0.5)CoO3(LSCO/PZT/LSCO)铁电电容器异质结,研究了Pb(Zr0.4Ti0.6)O3铁电薄膜的结构和物理性能.实验发现LSCO/PZT/LSCO铁电电容器具有良好的电学性能,在417kV/cm的驱动场强下,PZT铁电电容器具有较低的矫顽场强(125kV/cm)和较高的剩余极化强度(19.0μC/cm2),良好电容-电压特性(C-V)和保持特性,铁电电容器经过1010次反转后,极化强度没有明显下降,表明了非晶NiTi薄膜可以用作高密度硅基铁电存储器的扩散阻挡层.     

(La0.5Sr0.5)CoO3为电极的Pb(Zr0.4Ti0.6)O3和Pb(Zr0.2Ti0.8)O3铁电电容器结构及电学性能

分别采用磁控溅射法和溶胶-凝胶法(Sol-gel)制备了(La0.5Sr0.5)CoO3(LSCO)和Pb(Zr1-xTix)O3(PZT)薄膜,在Pt(111)/Ti/SiO2/Si基片上构架了LSCO/Pb(Zr0.4Ti0.6)O3(PZT(40/60))/LSCO和LSCO/Pb(Zr0.2Ti0.8)O3(PZT(20/80))/LSCO铁电电容器,研究了两种铁电电容器的结构和性能。XRD结构分析表明:两种四方相的不同Zr/Ti比例的PZT薄膜均为结晶良好的多晶钙钛矿结构。在5 V测试电压下,LSCO/PZT(40/60)/LSCO和LSCO/PZT(20/80)/LSCO两种铁电电容器的剩余极化强度(Pr)和矫顽场(Ec)分别为:28μC/cm2和1.2 V以及32μC/cm2和2 V。相对于PZT(40/60),PZT(20/80)具有较大的剩余极化强度和矫顽场,是由于其矩形度(c/a)较大。两种电容器都具有较好的脉宽依赖性和抗疲劳性。在5 V的测试电压下,LSCO/PZT(40/60)/LSCO电容器的漏电流密度为3.2×10-5A/cm2,LSCO/PZT(20/80)/LSCO电容器的漏电流密度为3.11×10-4A/cm2,经拟合分析发现:在0～5 V的范围内,两种电容器都满足欧姆导电机制。     

硅基Pt/Ba0.6Sr0.4TiO3/Pt电容器不同温度下的漏电机理研究

利用脉冲激光沉积技术在Pt(111)/TiO2/SiO2/Si(001)衬底上生长了厚度约为200 nm的Ba0.6 Sr04TiO3(BST)薄膜,构架了Pt/BST/Pt平行板电容器,测量了Ba06Sr0.4TiO3薄膜电容器在不同温度下的漏电流,研究了BST薄膜的结构和性能.结果表明BST薄膜为多晶钙钛矿结构,随着测量温度的降低,漏电流密度也随之降低,但是正负偏压下的J-V曲线并不对称,这主要归因于上下Pt电极与BST的界面热处理不同.通过不同导电机理对漏电流密度拟合发现,在负向偏置电压下,Pt/BST/Pt电容器均基本符合欧姆导电机制;而对于正向偏置电压,在低电压下符合欧姆导电机制,并且符合欧姆导电机制的电压范围在不断扩大,在高电压下符合空间限制电流(SCLC)导电机制.     

稀土离子对0.6Ca0.6La0.267TiO3-0.4Ca(Mg1/3Nb2/3)O3陶瓷微观组织结构及微波介电性能的影响

采用固相合成方法制备钙钛矿结构的0.6Ca06La0.267TiO3-0.4Ca(Mg1/3Nb2/3)O3微波介质陶瓷,研究了La3+、Nd3+、Sm3+、Ce4+掺杂对0.6CLT-0.4CMN体系微观组织结构和介电性能的影响.研究结果表明:稀土离子的掺杂,在0.6CLT-0.4CMN体系优良介电性能基础上有积极的改善效果,不同程度稀土离子掺杂对该体系的晶粒尺寸、气孔率等微观组织结构也有不同的影响.La3+、Nd3+、Sm3+、Ce4+6掺杂完全固溶到0.6CLT-0.4CMN陶瓷相中,并没有改变陶瓷主晶相,但会在一定程度上发生晶面衍射峰偏移.适量掺杂Ln3可以有效促进0.6CLT-0.4CMN陶瓷的致密化,提高0.6CLT-0.4CMN体系陶瓷的微波介电性能.La3+、Nd3+、Sm3+、Ce4+掺杂可以有效提高Q ×f值,并在一定程度上降低谐振频率温度系数.其中,掺杂0.75mol; Nd3+的0.6CLT-0.4CMN体系微波介电性能最佳(εr=66.7,Q×f=13037 GHz,rf=22.59 ppm/℃)     

含Ni-Al阻挡层硅基BiFe0.95Mn0.05O3铁电电容器的结构及物理性能

以Ni-Al为阻挡层,在Si衬底上构架了SrRuO3(SRO)/BiFe0.95Mn<0.05O3(BFMO)/SRO异质结电容器.x射线衍射(XRD)分析表明:Ni-Al阻挡层为非晶结构,BFMO薄膜为具有良好结晶质量的多晶结构.在5 kHz测试频率下,SRO/BFMO/SRO电容器呈现饱和的电滞回线.实验发现,SRO/BFMO/SRO铁电电容器具有良好的抗疲劳性能.漏电机制研究表明,外加电场小于210 kV/cm时,SRO/BFMO/SRO电容器满足欧姆导电机制,在电场大于210kV/cm时,满足空间电荷限流传导机制.     

碳酸钠共沉淀法制备LaNi0.6Fe0.4O3粉体的研究

以碳酸钠为沉淀剂,采用共沉淀法制备了亚微米级LaNi0.6Fe0.4O3(以下简称LNFO)粉体.研究了溶液离子总浓度,沉淀剂溶液pH,沉淀反应温度,滴定速率,前驱体热处理温度以及分散剂等因素对制备LNFO粉体的影响.采用X射线衍射分析(XRD)、差热失重分析(DSC-TG)、扫描电镜(SEM)对样品结构和形貌进行了表征.结果表明:前期混合液离子总浓度为0.4 mol/L,沉淀剂溶液pH为10,沉淀温度范围为60 ～80℃,滴定速率为30 mL/min,以CTAB为分散剂,所得前驱体在700℃煅烧2h后可得结晶程度良好的LNFO粉体.     

(Ba0.85Ca0.15)(Ti1-xZrx)O3无铅压电陶瓷的性能研究

采用固相法制备了(Ba0.85Ca0.15)(Ti1-xZrx)O3(BCTZ)无铅压电陶瓷,研究Zr含量(x=0～0.15)对BCTZ陶瓷微观结构和电性能的影响。结果表明:所有样品均具有纯的钙钛矿结构;随Zr含量的增加,室温下样品逐渐由四方相向三方相转变,在0.05相似文献   

硅基外延SrRuO3/PbZr0.5Ti0.5O3/SrRuO3电容器的结构和性能研究

传统的方法很难直接在硅衬底上制备外延的氧化物铁电电容器,本实验采用生长在硅衬底上的外延SrTiO3为模板,直接生长了SrRuO3/PbZr0.5Ti0.5O3/SrRuO3电容器异质结,并对其结构及性能进行了研究.X射线衍射表明所制备的SrRuO3/PbZr0.5Ti0.5O3/SrRuO3异质结实现了在硅衬底上的外延生长.在5V测试电压下,铁电电容器的剩余极化强度和矫顽电压分别为19.6μC/cm2和0.8V.当极化翻转次数达到1010时,铁电电容器的极化强度没有明显的衰减,表明SrRuO3/PbZr0.5Ti0.5O3/SrRuO3电容器具有良好的抗疲劳性能.     

聚乙二醇分散Ca0.6Mg0.4Zr4(PO4)6纳米粉的制备

以聚乙二醇(PEG4000)作分散剂,采用溶胶-凝胶法制备了Ca0.6Mg0.4Zr4(PO4)6(C0.6M0.4ZP)纳米粉。TG-DSC和XRD分析表明,凝胶经900℃热处理即可获得单相的C0.6M0.4ZP纳米粉。SEM和纳米粒度分析表明,未加入分散剂PEG试样,晶粒发生严重的团聚现象,平均粒径达到138nm,而加入PEG后,颗粒之间的团聚显著减轻,2.0%质量分数PEG分散后试样颗粒平均粒径仅为55nm。     

二乙醇胺辅助溶胶-水热法低温合成四方形貌Pb(Zr0.52Ti0.48)O3粉体

以醋酸铅、异丙醇钛、正丙醇锆为主要实验原料,采用改进的溶胶-水热复合法,在较低温度下制备出了四方形貌的Pb(Zr0.52Ti0.48) O3[简称PZT]纳米级粉体.探讨了二乙醇胺和水热反应温度对粉体结晶过程、粉体形貌、颗粒尺寸的影响.实验结果表明,二乙醇胺能够显著降低水热合成温度,有助于粉体在低温条件下合成.随着水热反应温度由150℃逐渐升高至200℃,PZT粉体由非晶态逐渐转变成含有少量杂质的四方相,最后形成了纯的四方相结构.粉体颗粒尺寸逐渐变小.当水热反应温度为180℃时,具有单一四方相结构的Pb(Zr0.52 Ti0.48)O3粉体呈现四方形貌,且团聚不明显.     

Structure and thermal stability of (Zr0.6Al0.4)O1.8 thin film on strained SiGe layer

Zr_0.6Al_0.4O_1.8 dielectric films were deposited directly on strained SiGe substrates at room temperature by ultra-high vacuum electron-beam evaporation (UHV-EBE) and then annealed in N₂ under various temperatures. X-ray diffraction (XRD) reveals that the onset crystallization temperature of the Zr_0.6Al_0.4O_1.8 film is about 900 °C, 400 °C higher than that of pure ZrO₂. The amorphous Zr_0.6Al_0.4O_1.8 film with a physical thickness of ∼12 nm and an amorphous interfacial layer (IL) with a physical thickness of ∼3 nm have been observed by high-resolution transmission electron microscopy (HRTEM). In addition, it is demonstrated there is no undesirable amorphous phase separation during annealing at temperatures below and equal to 800 °C in the Zr_0.6Al_0.4O_1.8 film. The chemical composition of the Zr_0.6Al_0.4O_1.8 film has been studied using secondary ion mass spectroscopy (SIMS).     

退火工艺对含Ti-Al阻挡层的硅基Pb(Zr_(0.4),Ti_(0.6))O_3铁电电容器结构和性能影响的研究

应用非晶的Ti-Al薄膜为导电阻挡层,采用射频磁控溅射法和溶胶-凝胶法在Si衬底上制备了La_(0.5)Sr_(0.5)CoO_3/Pb(Zr_(0.4),Ti_(0.6))O_3/La_(0.5)Sr_(0.5)CoO_3/Ti-Al/Si (LSCO/PZT/LSCO/Ti-Al/Si)异质结,研究了550 ℃常规退火(CTA)和快速退火(RTA)工艺对LSCO/PZT/LSCO/Ti-Al/Si结构和性能的影响.实验发现非晶Ti-Al薄膜在经过不同退火工艺后仍具有非晶结构,快速退火6 min的样品具有较好的物理性能.在418 kV/cm的外加电场下,LSCO/PZT/LSCO电容器的剩余极化强度和矫顽电场强度分别为22 μC/cm~2和83 kV/cm.LSCO/PZT/LSCO电容器的漏电行为不依赖于退火工艺,当电场强度低于46.7 kV/cm时为欧姆导电,高于46.7 kV/cm时为肖特基导电机制.     

La0.5Sr0.5CoO3/Pb(Zr0.4Ti0.6)O3/La0.5Sr0.5CoO3铁电电容器的结构和性能研究

采用磁控溅射法和脉冲激光沉积法,在SrTiO3(001)衬底上制备了La0.5Sr0.5CoO3(70 nm)/Pb(Zr0.4Ti0.6)O3(70 nm)/La0.5Sr0.5CoO3(70 nm) (LSCO/PZT/LSCO)铁电电容器异质结.X射线衍射结果表明:LSCO和PZT薄膜均为外延结构.在5 V的外加电压下, LSCO/PZT/LSCO电容器具有较低的矫顽电压(0.49 V),较高的剩余极化强度(41.7 μC/cm2 )和较低的漏电流密度(1.97×10-5 A/cm2),LSCO/PZT/LSCO电容器的最大介电常数为1073.漏电流的分析表明:当外加电压小于0.6 V时,电容器满足欧姆导电机制;当外加电压大于0.6 V时,符合空间电荷限制电流(SCLC)导电机制.     

非晶Ni-Al阻挡层对快速退火制备的硅基Ba0.6Sr0.4TiO3薄膜结构及物性影响的研究

应用非晶Ni-Al薄膜作为扩散阻挡层,采用磁控溅射法和溶胶-凝胶法在Pt/TiO2/SiO2/Si(001)衬底上制备了Pt/Ni-Al/Ba0.6Sr0.4TiO3/Ni-Al/Pt电容器结构,研究了在650～800 ℃温度范围内快速退火(RTA)工艺对电容器结构和物理性能的影响.结果表明:在外加电场为-100 kV/cm时,700 ℃和750 ℃退火样品的介电常数达到最大,分别为150和170.非晶Ni-Al薄膜的应用可以有效地降低BST薄膜的漏电流密度.650 ℃退火样品在整个测试电场范围内满足欧姆导电机制;700 ℃、750 ℃和800 ℃退火样品分别在电压低于-3.67 V、-2.65 V和-2.14 V时满足欧姆导电机制,在电压高于-3.67 V、-2.65 V和-2.14 V时满足普尔-弗兰克导电机制.     

Structural study of (As2S3)0.6(GeS2)0.4 glass

(As₂S₃)_0.6(GeS₂)_0.4 glass in non-irradiated and γ-irradiated states has been studied by using high-energy synchrotron X-ray diffraction, extended X-ray absorption fine structure spectroscopy, and positron annihilation lifetime spectroscopy. The experimental results are explained by the local changes around As and Ge atoms upon irradiation. These changes are suggested to involve chemical bonds distortion, formation of defective bonds with wrong coordination, rotation of structural units and appearance of additional free volume in the glass network.     

Growth of polar axis oriented tetragonal Pb(Zr,Ti)O3 films on CaF2 substrates with transparent (La0.07Sr0.93)SnO3

Epitaxial (La_0.07Sr_0.93)SnO₃ [LSSO] films were deposited on CaF₂ substrates by pulse laser deposition. The (1 0 0)_c orientation of LSSO films was observed only on (1 1 0)CaF₂, whereas (1 1 0)_c orientation was found on (1 1 1)CaF₂ and (1 0 0)CaF₂. (0 0 1) polar axis oriented tetragonal Pb(Zr_0.35Ti_0.65)O₃ films were grown on the fabricated (1 0 0)_cLSSO∥(1 1 0)CaF₂ by pulsed metal organic chemical vapor deposition. The (0 0 1)Pb(Zr_0.35Ti_0.65)O₃∥(1 0 0)cLSSO∥(1 1 0)CaF₂ stack structure exhibited about 70% transparency with an adsorption edge of approximately 330 nm.     

Potentiodynamic polarization studies on amorphous Zr46.75Ti8.25Cu7.5Ni10Be27.5, Zr65Cu17.5Ni10Al7.5, Zr67Ni33 and Ti60Ni40 in aqueous HNO3 solutions

Potentiodynamic polarization studies were carried out on virgin specimens of Zr-based bulk amorphous alloys Zr_46.75Ti_8.25Cu_7.5Ni₁₀Be_27.5 and Zr₆₅Cu_17.5Ni₁₀Al_7.5, and conventional-type binary amorphous alloys Zr₆₇Ni₃₃ and Ti₆₀Ni₄₀ in solutions of 0.2 M, 0.5 M and 1.0 M HNO₃ at room temperature. The values of the corrosion current density (I_corr) for the bulk amorphous alloy Zr_46.75Ti_8.25Cu_7.5Ni₁₀Be_27.5 were found to be comparable with those of Zr₆₅Cu_17.5Ni₁₀Al_7.5 in 0.2 M and 0.5 M HNO₃, but the value of I_corr for the former was almost three times more than that of the latter in 1.0 M HNO₃. In the case of conventional binary amorphous alloys, Ti₆₀Ni₄₀ showed lower value of I_corr as compared to Zr₆₇Ni₃₃ in 0.5 M and 1.0 M HNO₃ and a comparable value of I_corr in 0.2 M HNO₃. In general, the binary Ti₆₀Ni₄₀ displayed the best corrosion resistance among all the alloys in all the cases and the corrosion current density (I_corr) for all the alloys was found to increase with the increasing concentration of nitric acid. It is noticed that the bulk amorphous alloys do not possess superior corrosion resistance as compared to conventional binary amorphous alloys in aqueous HNO₃ solutions. The observed differences in their corrosion behavior are attributed to different alloy constituents and composition of the alloys investigated.