Fabrication of tungsten films by metallorganic chemical vapor deposition

Tungsten films growing on copper substrates were fabricated by metallorganic chemical vapor deposition (MOCVD). The chemical purity, crystallographic phase, cross-sectional texture, and resistivity of the deposited films both before and after annealing treatment were investigated by X-ray energy-dispersive spectroscopy (EDS), X-ray diffraction (XRD), scanning electron microscopy (SEM), and four-point probe method. It is found that the films deposited at 460℃ are metastable β-W with (211) orientation and can change into α-W when annealed in high-purity hydrogen atmosphere at high temperature. There are small amounts of C and O in the films, and the W content of the films increases with increasing deposition temperature and also goes up after annealing in high-purity hydrogen atmosphere. The films have columnar microstructures and the texture evolution during their growth on copper substrates can be divided into three stages. The resistivity of the as-deposited films is in the range of 87-104 μΩ·cm, and low resistivity is obtained after annealing in high-purity hydrogen atmosphere.     

溅射功率及压强对磁控溅射Mo薄膜电学性能和表面形貌的影响

采用直流磁控溅射的方法在普通玻璃衬底上沉积Mo薄膜,研究了工作压强、溅射功率对Mo薄膜的电学性能、表面形貌的影响.实验表明,在我们所使用的压强范围内(O.2～2.O Pa),溅射压强低时,沉积速率较快,制备出的薄膜导电性能亦较好;O.4 Pa时达到最佳值,电阻率为1.22×10-4Ω·cm,且扫描电镜(SEM)图显示薄...     

衬底负偏压溅射对ZrN薄膜性能的影响研究

本文采用S-抢磁控溅射系统淀积ZrN薄膜,用扫描电镜、X射线衍射、反射电子衍射、俄歇电子能谱和电学测量等方法研究了衬底负偏压溅射和溅射两种工艺方法淀积的ZrN薄膜的结构、组分和薄膜电阻率。结果表明,适当增大溅射功率,采用衬底负偏压溅射方法,有效地减少了氧的沾污,使得所淀积的ZrN薄膜的电学性能有明显改善。     

溅射功率对氧化铝薄膜结构和光学性能的影响

采用射频反应磁控溅射法,在K9双面抛光玻璃基底上制备了一系列不同溅射功率的Al2O3薄膜,并对部分薄膜进行退火处理.利用X线衍射法对Al2O3薄膜退火前后的晶体结构进行分析,采用椭圆偏振光谱仪对薄膜的厚度、折射率和消光系数进行测试和拟合.实验结果表明:测射功率在100~300 W时,沉积的Al2O3薄膜退火前后均为非晶态;薄膜在可见光范围内具有良好的透光性能,透射率接近90%,为透明膜;薄膜的沉积速率随溅射功率的增大而增大;薄膜在可见光波段的折射率n随波长的增大而减小,平均值随溅射功率的增大呈现出先增大后减小的变化趋势;薄膜消光系数k的平均值亦随溅射功率的增大呈现先增大后减小的变化趋势.     

H2/(Ar+H2)流量比对AZO薄膜结构及光电性能的影响

在Ar+H2气氛下,用RF磁控溅射法在室温下制备Al掺杂的ZnO(AZO)薄膜,研究H2/(Ar+H2)流量比对薄膜结构和光电性能的影响。结果表明,在沉积气氛中引入H2可以提高AZO薄膜的结晶质量,降低AZO薄膜的电阻率,提高其霍尔迁移率和载流子浓度;H2/(Ar+H2)流量比为5%时,AZO薄膜的最小电阻率为1.58×10-3Ω.cm,最大霍尔迁移率和载流子浓度分别为13.17cm2.(V.s)-1和3.01×1020 cm-3;AZO薄膜在可见光范围内平均透光率大于85.7%。     

Influence of modulation period for β-Cu2+xSe/SiC nano-multilayer films on their thermoelectric properties

In this study, β-Cu_2+xSe/SiC nano-multilayer films with different modulation period were successfully deposited on SiO₂/Si substrates by sputtering alternately using Cu–Se and SiC targets. The deposited films were observed on both surface and cross-section, and the thermoelectric properties were studied. The results show that both carrier concentration and mobility at room temperature decreased with the reducing modulation period for the nano-multilayer films. The conductivity slightly decreased and Seebeck coefficient greatly increased with the reducing modulation period. As a result of competition, the power factor of the nano multilayer films increased with the reducing modulation period because the positive effect of the Seebeck coefficient exceeded the negative effect of the conductivity. In the case of β-Cu_2+xSe/SiC nano multilayer film with the smallest modulation periods (210 ?nm), the power factor reached 0.39 ?mWm^?1K^?2 and 0.59 ?mWm^?1K^?2 at room temperature and 325 ?°C, respectively. The enhanced power factor for nano multilayer films is attributed to the scattering process at the β-Cu_2+xSe/SiC layer interface, which reduces the carrier concentration and the mobility. It is concluded that the thermoelectric properties of β-Cu_2+xSe films can be effectively improved by designing nano multilayer structure.     

溅射功率和工作气压对磁控溅射铬薄膜光电学性质的影响

采用直流磁控溅射方法在石英基片上沉积铬薄膜.研究溅射功率、工作气压对铬薄膜结构、电学和光学性质的影响.利用X射线衍射仪、分光光度计和Van der Pauw方法分别检测薄膜的结构、光学和电学特性,利用德鲁特模型和薄膜的透射、反射光谱计算薄膜的厚度和光学常数.结果表明:制备的铬薄膜为体心立方的多晶态;在工作气压0.6Pa一定时,随着溅射功率从40W增加到120W,沉积速率呈非线性增加,薄膜更加致密,电阻率连续降低,在550nm波长处,薄膜的折射率从3.52增大到功率80W时的最大值(3.88),尔后逐渐减小至3.69;消光系数从1.50逐渐增大到2.20;在溅射功率80W一定时,随着工作气压从0.4Pa增加到1.2Pa,沉积速率呈近线性降低,薄膜的电阻率逐渐变大,在550nm波长处,折射率从3.88减小到3.62,消光系数从2.55减小到1.48.     

膜厚对柔性ZnO∶Ga透明导电薄膜结构和电学性能的影响

室温下采用直流磁控溅射法在PI衬底上制备出具有优异光学性能的ZnO∶Ga透明导电薄膜.研究结果表明,制备了具有C轴择优取向的六角纤锌矿结构的多晶GZO透明导电薄膜.讨论了薄膜厚度对PI衬底上制备ZnO∶Ga薄膜的结构、表面形貌和电学性质的影响.实验数据表明,一定同质缓冲层可有效降低薄膜应力,改善薄膜性能,所得GZO薄膜厚度为129nm时,电阻率具有最小值3.2×10-4Ω.cm.     

Influence of O2/Ar ratio on the properties of transparent conductive niobium-doped ZnO films

Niobium-doped ZnO transparent conductive films are deposited on glass substrates by radio frequency sputtering at 300℃. The influence of O2/Ar ratio on the structural, electrical and optical properties of the as-deposited films is investigated by X-ray diffraction, Hall measurement and optical transmission spectroscopy. The lowest resistivity of 4.0×10^-4Ω· cm is obtained from the film deposited at the O2/Ar ratio of 1/12. The average optical transmittance of the films is over 90%.     

采用不同功率溅射制备氧化钛薄膜的研究

常温下,利用射频（RF）反应磁控溅射方法在K9双面抛光玻璃基底上沉积氧化钛薄膜．采用光栅光谱仪对薄膜样品的透射谱进行测试,通过椭圆偏振光谱仪测试并拟合得到薄膜的厚度、折射率和消光系数等光学参数,借助掠入射角X-射线衍射对薄膜的结晶状态进行了测试．实验结果表明：不同溅射功率下沉积的样品呈非晶态,在40～100W范围内,溅射功率越大,薄膜的沉积速率越大,但溅射功率对折射率和消光系数影响不大．     

Effect of La and Co-doping on microstructure and electrical properties of Bi FeO_3 thin films

Adding both La3＋and Co3＋was used to tune the microstructure and electrical properties of Bi Fe O3（BFO） thin films, and Bi1-xLaxFe0.90Co0.10O3 thin films were grown on the Sr Ru O3-buffered Pt-coated silicon substrates by a radio frequency sputtering. A polycrystalline structure with（110） orientation was shown in thin films, and their resistivity dramatically increases as the La3＋content increases. Their dielectric constant increases,and dielectric loss decreases with increasing La3＋content.In addition, their ferroelectric and fatigue properties were enhanced with rising La3＋content. The thin films with x = 0.03 have optimum electrical properties（e.g., remanent polarization 2Pr＊ 175.6 l C/cm2, coercive field2Ec＊ 699.5 k V/mm, dielectric constant er＊ 257 and tan d ＊ 0.038）, together with a good fatigue behavior. The impendence analysis of the films was conducted to identify the defects type during conductivity, and both hopping electrons and single-charged oxygen vacancies are mainly responsible for the conduction of grain and grain boundaries regardless of La3＋content. As a result, the doping with both La3＋and Co3＋benefits the improvement in the electrical properties of BFO thin films.     

Grain size-dependent electrical resistivity of bulk nanocrystalline Gd metals

The electrical resistivity of the as-consolidated and coarse-grained bulk gadolinium(Gd) metals was studied in the temperature range of 3-315K.The experimental results showed that with decrease in the grain size of Gd grains from micrometer to nanometer range,the room temperature electrical resistivity increased from 209.7 to 333.0 μΩcm,while the electrical resistivity at the low temperature of 3K was found to increase surprisingly from 16.5 to 126.3 μΩcm.The room temperature coefficient resistivity(TCR) values were obtained as 39.2×10-3,5.51×10-3 and 33.7×10-3K-1.The ratios of room temperature to residual resistivity [RRR=ρ(300K)/ρ(3K)] are 2.64,11.0,respectively,for the as-consolidated samples at 280℃ and 700℃ with respect to that of the coarse-grained sample.All results indicate the remarkable influence of the nanostructure on the electrical resistivity of Gd due to the finite size effect and large fraction of grain boundaries.     

Enhanced thermoelectric performance of rough silicon nanowires

Approximately 90 per cent of the world's power is generated by heat engines that use fossil fuel combustion as a heat source and typically operate at 30-40 per cent efficiency, such that roughly 15 terawatts of heat is lost to the environment. Thermoelectric modules could potentially convert part of this low-grade waste heat to electricity. Their efficiency depends on the thermoelectric figure of merit ZT of their material components, which is a function of the Seebeck coefficient, electrical resistivity, thermal conductivity and absolute temperature. Over the past five decades it has been challenging to increase ZT > 1, since the parameters of ZT are generally interdependent. While nanostructured thermoelectric materials can increase ZT > 1 (refs 2-4), the materials (Bi, Te, Pb, Sb, and Ag) and processes used are not often easy to scale to practically useful dimensions. Here we report the electrochemical synthesis of large-area, wafer-scale arrays of rough Si nanowires that are 20-300 nm in diameter. These nanowires have Seebeck coefficient and electrical resistivity values that are the same as doped bulk Si, but those with diameters of about 50 nm exhibit 100-fold reduction in thermal conductivity, yielding ZT = 0.6 at room temperature. For such nanowires, the lattice contribution to thermal conductivity approaches the amorphous limit for Si, which cannot be explained by current theories. Although bulk Si is a poor thermoelectric material, by greatly reducing thermal conductivity without much affecting the Seebeck coefficient and electrical resistivity, Si nanowire arrays show promise as high-performance, scalable thermoelectric materials.     

束参数对离子束溅射法所淀积非晶硅电特性的影响

本文论述了用离子束溅射淀积非晶硅(a-Si)和氢化非晶硅(a-Si:H)的方法,提供了加速电压和衬底位置改变对薄膜暗电阻率的影响结果,通过有关淀积工艺条件的研究,得出了一些有用的结论。     

压力对稀土元素Sm填充方钴矿化合物热电性能的影响

通过高温高压方法合成出稀土元素Sm填充n型方钴矿化合物SmxCo4Sb12（0〈x〈1）,并考察了在室温下Sm填充率对热电性能的影响规律.结果表明：SmxCo4Sb12化合物表现为n型传导;电阻率和Seebeck系数随着合成压力的增加逐渐增加;晶格热导率随着Sm填充分数的增加而降低,在Sm填充量为0.5时达到最小值.室...     

Ba和Y掺杂对Ca_3Co_4O_9热电性能的影响

采用固态反应法制备了Ca_(3-x)Ba_xCo_4O_9(0.00≤x≤0.20)和Ca_(3-y)Y_yCo_4O_9(0.00≤y≤0.20)热电材料.X射线衍射(XRD)分析结果表明,对于Ba掺杂和Y掺杂,在掺杂范围内,样品为单一的Ca_3Co_4O_9相.在室温至1000K的范围内样品的电阻率和Seebeck系数测量结果显示,用Ba~(2+)替代Ca~(2+)时,随着x的增加,电阻率逐渐减小、Seebeck系数几乎不变;用Y3+替代Ca2+时,Seebeck系数随着y的增加逐渐增大、而电阻率在x等于0.025时最小.当T=1000K时,样品Ca_(2.95_Ba_(0.05)Co_4O_9和Ca_(2.97)5Y_(0.025)Co_4O_9的功率因子与Ca_3Co_4O_9相比都明显提高.     

室温下金属铝膜的霍尔效应初步研究

采用真空蒸发镀膜法制备了金属铝薄膜,在室温下,用四探针法测量了样品的电阻率和霍尔系数。结果表明,制成的金属铝膜,电阻率由块体材料的10^-8Ω·m 增大到薄膜样品的10^-5Ω·m;霍尔系数由块体材料的10^-11m³/C数量级左右增大到10^-4m³/C数量级;电阻率和霍尔系数随着金属铝膜厚度的减小而逐渐增大。     

衬底温度和溅射功率对AZO薄膜性能的影响

采用RF磁控溅射法在载玻片上制备了可用于电极材料的掺Al氧化锌(AZO)透明导电薄膜,并对不同衬底温度和溅射功率下制备的AZO薄膜结构、光电性能进行了表征分析.结果表明:各种工艺条件下沉积的AZO薄膜均具有明显的(002)择优取向,没有改变ZnO六方纤锌矿结构;薄膜电阻率随衬底温度升高而减小,随溅射功率增加先减小后增大,衬底温度400℃、溅射功率200W时最小,为1.53×10-5Ω.m;可见光平均透射率均在80%以上,光学带隙与载流子浓度变化趋势一致,最大值为3.52eV.     

Influence of post-annealing on the properties of Ta-doped In<Subscript>2</Subscript>O<Subscript>3</Subscript> transparent conductive films

Ta-doped In₂O₃ transparent conductive oxide films were deposited on glass substrates using radio-frequency (RF) sputtering at 300°C. The influence of post-annealing on the structural, morphologic, electrical and optical properties of the films was investigated using X-ray diffraction, field emission scanning electron microscopy, Hall measurements and optical transmission spectroscopy. The obtained films were polycrystalline with a cubic structure and were preferentially oriented in the (222) crystallographic direction. The lowest resistivity, 5.1×10⁻⁴ Ω cm, was obtained in the film annealed at 500°C, which is half of that of the un-annealed film (9.9×10⁻⁴ Ω cm). The average optical transmittance of the films was over 90%. The optical bandgap was found to decrease with increasing annealing temperature.     

ZAO透明半导体薄膜的研究

采用直流磁控溅射ZAO陶瓷靶的工艺,在玻璃衬底上成功地镀刺了ZAO透明半导体膜,获得了电阻率6×10^-4Ωcm和可见光透过率85％以上的ZAO薄膜最佳光电特性参数．