HWP-CVD氮化硅薄膜的结构和光学特性

采用傅立叶红外吸收谱和紫外-可见透射谱研究了螺旋波等离子体增强化学气相沉积法制备的氢化非晶氮化硅薄膜的原子间键合结构和光学特性。结果表明,在不同硅、氮活性气体配比R下,薄膜表现出不同的Si/N比和H原子键合方式,富氮样品中H原子主要和N原子结合,而富硅样品中主要和Si原子结合。随着R的增加,薄膜的光学带隙E_g和E₀₄逐渐减小,此结果关联于薄膜结构无序性程度的增加,而薄膜的(E₀₄-E_g)和Tauc斜率B值之间存在着相互制约关系。     

氮化硅透明陶瓷光学薄膜的制备与特性分析

采用射频磁控反应溅射法在不同工艺下制备微米级厚度的氮化硅薄膜,并利用椭圆偏振仪、分光光度计、X射线衍射仪、电子探针显微分析仪以及红外光谱仪对薄膜的光学性能、微观结构及化学成分进行了表征。测试结果表明,当N2和Ar的流量为1∶1时所制备样品为非晶态结构的高折射率富氮氮化硅薄膜;低温热处理对薄膜折射率有一定的改善作用;透过率随溅射气压的增加而升高、随功率的增大而降低;N-Si键的强度随溅射气压的升高而降低。     

非平衡磁控溅射沉积Ta-N薄膜的结构与电学性能研究

采用直流反应非平衡磁控溅射技术在单晶Si(100)和玻璃表面沉积氮化钽(Ta-N)薄膜,分别测试了薄膜的结构、成分、电阻率和吸收光谱,研究了氮氩流量比(N2∶Ar)变化对Ta-N薄膜的结构和电学性能的影响.研究结果表明随N2∶Ar增加,依次生成六方结构的γ-Ta2N、面心立方结构(fcc)的δ-TaNx、体心四方结构(bct)的TaNx;N2∶Ar在0.2～0.8的范围内,Ta-N薄膜中只存在着fcc δ-TaNx;当N2∶Ar＞1之后,Ta-N薄膜中fcc δ-TaNx和bct TaNx共存.Ta-N薄膜电阻率随N2∶Ar流量比增加持续增加,当N2∶Ar为1.2时,薄膜变为绝缘体,光学禁带宽度为1.51eV.     

氮掺杂氟化非晶碳薄膜光学性质的研究

用射频等离子体增强化学气相沉积(RF-PECVD)法制备氮掺杂氟化非晶碳(a-C:F:N)薄膜.用紫外-可见分光光谱仪、椭偏仪、傅立叶变换红外光谱仪对薄膜进行了检测.结果表明:随源气体中氮气含量的增加,光学带隙先减小后升高,折射率变化情况与之相反.在其它条件相同的情况下,升高沉积温度使得薄膜的光学带隙和折射率降低.光学带隙的大小与sp2键含量密切相关,sp2键浓度越大,薄膜的光学带隙越小.     

GaN薄膜的制备及其振动光谱的密度泛函理论研究

以氧化镓为镓源, 用溶胶-凝胶和高温氨化二步法, 在Si(111)衬底上制备出GaN薄膜. X射线衍射(XRD)分析表明制备的GaN薄膜是六角纤锌矿结构; 扫描电子显微镜(SEM)图片显示GaN晶粒的尺寸<100nm; 薄膜的红外光谱(FTIR)中有GaN的E1 (TO)声子模式. 用密度泛函理论(DFT)计算了氮化镓小团簇的振动频率. 结果表明: 富镓氮化镓团簇的振动频率在六方晶系纤锌矿结构GaN的光学声子峰值附近; 富氮氮化镓团簇中的N--N键的振动频率为2200cm^-1. 用氮化镓团簇的频谱对所制薄膜的红外光谱作了进一步分析.     

氮分压对反应溅射(Ti,Al)N薄膜微结构与力学性能的影响

采用Ti-Al复合靶在不同氮分压下制备了一系列(Ti,Al)N薄膜,用EDS、XRD、TEM和微力学探针表征了薄膜的沉积速率、化学成分、微结构和力学性能.结果表明,氮分压对(Ti,Al)N薄膜影响显著:合适的氮分压可以得到化学计量比的(Ti,Al)N薄膜,薄膜为单相组织,并呈现(111)择优取向,最高硬度和弹性模量分别达到34.4GPa和392GPa;过低的氮分压不但会造成薄膜贫氮,而且薄膜中的Al含量偏低,硬度不高;过高的氮分压下,由于存在"靶中毒"现象,尽管薄膜的成分无明显变化,但会大大降低其沉积速率,并使薄膜形成纳米晶或非晶态结构,薄膜的硬度也较低.     

磁控溅射法制备CNx薄膜及其结构表征

以Ar/N2混合气体作为溅射气体,利用直流磁控溅射的方法制备子碳氮薄膜.利用X射线衍射和红外光谱对碳氮薄膜进行了结构分析.IR光谱证实了薄膜中碳氮化合物的形成,而XRD的检测结果表明,类石墨相g-C3N4是碳氮薄膜中的主要成分,同时有极少量的β-C3N4晶相生成.同时发现,Ar/N2溅射气体的分压对获取β-CsN4有着明显的影响.本实验中,当N2体积分数为33%,碳氮薄膜中β-C3N4晶相的含量最高.     

氮分压与衬底温度对光透明材料氮化锌的影响

采用射频磁控溅射方法,在Ar-N2混合气中Si衬底上生长Zn3N2薄膜。研究了氮分压和衬底温度对样品的光透明性、微结构、表面形貌以及光学性质的影响,同时研究了样品在空气氛围下保持20天后的性能,并与新镀薄膜进行比较。结果表明,Zn3N2薄膜直接光学带隙可由氮分压调节的范围为1.18~1.50eV,氮分压比例增大,薄膜的光透明性减弱,并且对暴露在空气中20天以后的薄膜进行测试发现,薄膜的光透明性明显增强,随着衬底温度的升高,生长的薄膜择优取向增多,晶粒尺寸逐渐变大。     

氮流量对TaN薄膜微结构及性能的影响

采用反应直流磁控溅射法在Al2O3陶瓷基片上制备TaN薄膜,研究了氮流量(N2/(N2+Ar))对TaN薄膜微结构及性能的影响。结果表明,随氮流量的增大,TaN薄膜的氮含量、电阻率、方阻以及TCR的绝对值逐渐增大,而沉积速率逐渐降低。当N2流量较低(2%～4%)时,TaN薄膜中主要含有电阻率和TCR绝对值较低的六方Ta2N相(hcp),薄膜的电阻率在344μΩ.cm到412μΩ.cm范围内,薄膜的TCR绝对值约为几十ppm/℃。当氮气流量较高(5%～6%)时,薄膜中Ta2N相消失,薄膜中主要含有TCR绝对值较大的体心四方结构(bct)的TaN和四方结构(bct)的Ta3N5相,薄膜的电阻率在940μΩ.cm到1030μΩ.cm范围内,薄膜的TCR绝对值约为几百ppm/℃。     

非晶碳膜及掺氮非晶碳膜的制备及光学性质的比较

用射频磁控溅射法成功地制备了非晶碳薄膜薄膜。拉曼光谱表征表明所沉积的非晶碳薄膜是非晶结构,具有类金刚石特性。对所制备的掺氮非晶碳薄膜用光电子能谱和红外光谱进行了表征。同时还研究了两种薄膜的光学性质,为该类薄膜的实际应用提供了可靠的实验依据     

New superconducting equiatomic ternary silicides MIrSi (M = Y,Zr, Hf) with TiNiSi-type structure (anti-PbCl2)

New equiatomic ternary silicides MIrSi (M = Y, Ti, Zr, Hf) crystallizing with the TiNiSi-type structure (anti-PbCl₂) have been prepared. Those with Y(T_cr = 2.70 K), Zr(T_cr = 2.04 K) and Hf(T_cr = 3.50 K) are the first superconducting ternary silicides having such a structure. The titanium compound has not been found to be superconducting above 1.7 K.     

Structures and electronic properties of M2C2 @ C78 (M = Ti, Zr, Hf): a density functional theory study

A systematic DFT investigation has been conducted to explore the structures and electronic properties of the metal-carbide endofullerenes M2C2 @ C78 (M = Ti, Zr, Hf) at the PBE/DNP level of theory. The theoretical calculations predicted the following: (i) this series of endofullerenes have the valence states [M4+]2C2(2-) @ C78(6-) (ii) the structure of the [M2C2](6+) cluster encapsulated in the C78(6-) (D3h) cage varies with the increasing of the ionic radius of M4+, i.e., from a linear M-C [triple bond] C-M geometry for M = Ti, through a zigzag geometry for M = Hf to a side-on binding mode for M = Zr; (iii) M2C2 @ C78 (M = Zr, Hf) should display interesting intramolecular dynamic behavior at room temperature, i.e., the encapsulated C2(2-) moiety can rotate freely around the C3-axis of the C78(6-) (D3h) cage; (iv) the [Ti2C2]6+ in the lightest Ti2C2 @ C78 is far more fixed by adopting the linear Ti-C - C-Ti geometry; (v) the order for their ionization potentials is Ti2C2 @ C78 < Hf2C2 @ C78 < Zr2C2 @ C78, whereas their EAs follow the order: Ti2C2 @ C78 < Hf2C2 @ C78 approximately Zr2C2 @ C78. The predicted redox properties of these endofullerenes suggest that Zr2C2 @ C78 is synthetically as approachable as Hf2C2 @ C78.     

Study of (Zr,Ti)CN, (Zr,Hf)CN and (Zr,Nb)CN films prepared by reactive magnetron sputtering

(Zr,Ti)CN, (Zr,Hf)CN and (Zr,Nb)CN coatings, in which Ti, Hf and Nb were added to ZrCN base compound, have been prepared by reactive magnetron sputtering. The coatings, with two different non-metal/metal ratios, were comparatively investigated in terms of elemental and phase composition, texture, surface morphology, hardness and friction performance. It has been shown that the films exhibit nanocomposite structures, consisting of a mixture of crystalline metal carbonitride and amorphous carbon. As compared with ternary ZrCN coatings, the quaternary coatings were found to exhibit superior mechanical and friction characteristics. In general, the films with higher non-metal content revealed finer morphologies, higher hardness and lower friction coefficient. Depending on the coating type and non-metal/metal ratio, the hardness values ranged from about 21 to 29 GPa, being higher than those of ZrCN reference films. The coefficients of friction varied from 0.2 to 0.5, the lowest values being obtained for the coatings with the highest non-metal content.     

室温磁控溅射制备(Ti,Zr)N薄膜及其性能研究

采用直流反应磁控溅射工艺,在载波片和Al基材上制备出金黄色的(Ti,Zr)N薄膜.(Ti,Zr)N薄膜具有比TiN薄膜更高的硬度和更强的耐腐蚀性能.用XRD衍射方法和扫描隧道显微镜对薄膜的晶体结构、微观表面形貌和电子结构进行了测试分析.XRD结果表明,(Ti,Zr)N薄膜为多晶态,存在TiN和ZrN两种分离相;从表面形貌可知,薄膜表面平整,晶粒排列致密且无连接松散的大颗粒;STS谱表明,Zr掺杂后,禁带宽度仍为1.64eV,但在禁带内增加了新能级,新能级的宽度分别为0.33eV和0.42eV,这也正是掺杂Zr后,薄膜仍呈现金黄色的主要原因.     

Sputter alloying of Ni,Ti and Hf for fabrication of high temperature shape memory thin films

Abstract

In the present paper, the fabrication and characterisation of typical high temperature Ni(Ti+Hf) alloyed thin films produced by simultaneous sputter deposition from separate elemental Ni, Ti and Hf targets are presented. Film composition, determined by energy dispersive X-ray spectroscopy, was controlled by adjusting the ratio of powers applied to each target. Films deposited at room temperature had an amorphous structure and subsequent annealing at 550°C was carried out in a high vacuum environment, based on crystallisation temperature evaluation by differential scanning calorimetry (DSC). High temperature martensitic transformation, confirmed by DSC and variable temperature X-ray diffraction (XRD), was achieved by deposition of (Ti+Hf) rich Ni–Ti–Hf films. Any slight change of composition towards Ni rich reduced the transformation temperature. Atomic force microscopy and XRD illustrated that the films had a fine grain structure (～100 nm). One way shape memory effect was observed at ～200°C in a film with composition of 15·6 at.-%Hf.     

Electromagnetic wave absorbing properties of TMCs (TM=Ti,Zr, Hf,Nb and Ta) and high entropy (Ti0.2Zr0.2Hf0.2Nb0.2Ta0.2)C

Electromagnetic wave (EMW) absorbing materials play a vital role in modern communication and information processing technologies to inhibit information leakage and prevent possible damages to environment and human bodies.Currently,most of EMW absorbing materials are either composites of two or more phases or in the form of nanosheets,nanowires or nanofibers in order to enhance the EMW absorption performance through dielectric loss,magnetic loss and dielectric/magnetic loss coupling.However,the combination of complex shapes/multi phases and nanosizes may compound the difficulties of materials processing,composition and interfaces control as well as performance maintenance during service.Thus,searching for single phase materials with good stability and superior EMW absorbing properties is appealing.To achieve this goal,the EMW absorbing properties of transition metal carbides TMCs (TM=Ti,Zr,Hf,Nb and Ta) and high entropy (Ti0.2Zr0.2Hf0.2Nb0.2Ta0.2)C which belong to ultrahigh temperature ceramics,were investigated in this work.Due to the good electrical conductivity and splitting ofd orbitals into lower energy t2g level and higher energy eg level in TMC6 octahedral arrangement,TMCs (TM=Ti,Zr,Hf,Nb and Ta) exhibit good EMW absorbing properties.Especially,HfC and TaC exhibit superior EMW absorbing properties.The minimum reflection loss (RLmin) value of HfC is -55.8 dB at 6.0 GHz with the thickness of 3.8 mm and the effective absorption bandwidth (EAB) is 6.0 GHz from 12.0 to 18.0 GHz at thickness of 1.9 mm;the RLmin value of TaC reaches-41.1 dB at 16.2 GHz with a thickness of 2.0 mm and the EAB is 6.1 GHz with a thickness of 2.2 mm.Intriguingly,the electromagnetic parameters,i.e.,complex permittivity and permeability are tunable by forming single phase solid solution or high entropy (Ti0.2Zr0.2Hf0.2Nb0.2Ta0.2)C.The RLmin value of high entropy (Ti0.2Zr0.2Hf0.2Nb0.2Ta0.2)C is -38.5 dB at 9.5 GHz with the thickness of 1.9 mm,and the EAB is 2.3 GHz (from 11.3 to 13.6 GHz) atthickness of 1.5 mm.The significance of this work is that it opens a new window to design single phase high performance EMW absorbing materials by dielectric/magnetic loss coupling through tuning the conductivity and crystal field splitting energy of d orbitals of transition metals in carbides,nitrides and possibly borides.     

Effect of dopants on the soft magnetic properties and high frequency characteristics of FeCoBM (M = Ti, Nb, Hf, and Ta) thin films

Effect of dopants on the soft magnetic properties and high frequency characteristics of FeCoBM thin films (M = Ti, Nb, Hf, and Ta) have been studied. For (Fe0.55Co0.45)(100-x)B(x) (x = 5-15) thin films, with the increase of B content, the resistivity was increased because B could decrease the crystallinity of the films. The (Fe0.55Co0.45)90B10 thin film showed the optimum properties, where 4piM(s) = 16.1 kG, H(ce) = 64.2 Oe, H(ch) = 13.5 Oe, H(k) = 310 Oe and p = 338 microomega-cm. To reduce the coercivity of the film, the elements M, including Ti, Nb, Hf, and Ta, were selected to substitute for B in the FeCoB films. It was found that (Fe0.55Co0.45)90B6Ti2Nb2 thin film after annealing at a temperature of 200 degrees C for 30 min showed the optimal properties, where 4piM(s) = 15.8 kG, H(ce) = 4.8 Oe, H(ch) = 3.6 Oe, H(k) = 224 Oe and p = 290 microomega-cm. The theoretically calculated ferromagnetic resonance frequency of the developed films can be higher than 5 GHz.     

(Ti,Al,Zr)N多元氮梯度硬质反应膜的组织结构和性能

采用多弧离子镀技术和Ti-Al合金靶及Zr单质靶的组合,在高速钢基体上制备了(Ti,Al,Zr)N多元N梯度硬质反应膜.分别用扫描电镜、X射线衍射仪观察测定(Ti,Al,Zr)N梯度膜膜层的表面、断面形貌、成分以及相结构,研究了(Ti,Al,Zr)N多元氮梯度硬质反应膜的组织结构和性能.结果表明,与TiN、(Ti,Al...     

Mechanical properties of single crystals of transition metals diborides TMB<Subscript>2</Subscript> (TM = Sc,Hf, Zr,Ti). Experiment and theory

The mechanical behaviour of TMB₂ whiskers (TMB₂ = Sc, Hf, Zr, Ti) of 10–20 μm in diameter of the directionally reinforced ceramics LaB₆–TMB₂ was experimentally studied by the nanoindentation. The pop-in (the abrupt elastic–plastic transition in the indenter penetration) caused by the nucleation of dislocations in the previously dislocations-free region under the imprint was observed in all samples under study. For the first time the experimental estimations of the theoretical shear strength of these materials are obtained. Zone structures and types of interatomic bonds for TMB₂ (TM= Sc, Zr, Hf, Ti) are theoretically calculated. The effects of the electronic structures on mechanical properties of diborides of transition metals were analyzed.     

Hafnium and zirconium tetramethylnonanedionates as new MOCVD precursors for oxide films

New bulky Zr and Hf β-diketonates (2,2,8,8-tetramethyl-4,6-nonanedionates, tmnd) were synthesized and characterized by elemental analyses, ¹H NMR, FT-IR and mass spectrometry. A volatile copper compound Cu(tmnd)₂, an intermediate product of ligand synthesis, was isolated and characterized as well. The M(tmnd)₄ (M=Zr, Hf) compounds were tested as precursors for MOCVD of ZrO₂ and HfO₂ films. Preferentially (001)/(010)/(100) textured and in-plane oriented films of monoclinic oxides have been deposited by pulsed liquid injection MOCVD on R plane sapphire. Smooth films could be grown, especially on sapphire and at low temperature (500 °C). The films on Si(100) were polycrystalline and had rougher surface. XPS study showed 3–4 and 7–8 at.% of carbon in HfO₂ and ZrO₂ films, respectively. Zr(tmnd)₄ and Hf(tmnd)₄ lead to significantly higher growth rates of ZrO₂ and HfO₂ films at low temperature than conventional Zr(thd)₄ and Hf(thd)₄ precursors (thd=2,2,6,6-tetramethyl-3,5-heptanedionate) and are attractive precursors for oxide films.