由纳米棒和纳米叶组成的铁磁性的MnSb薄膜

提供了一种利用物理蒸发沉积技术在单晶硅上生长纳米尺度的MnSb薄膜的方法.X射线衍射分析表明薄膜的主要成分是MnSb合金.场发射扫描电镜观察到薄膜是由纳米尺寸的棒状物和叶状物组成.纳米棒的平均直径为20nm,长度在几百纳米范围内.纳米叶的厚度大约为20nm,宽度为100nm左右.用可变梯度磁力计测量了薄膜的磁滞回线,结果显示薄膜有很强的几何各向异性.     

铁磁/半导体异质结材料MnSb/Si的物理气相沉积生长

采用一种新的生长铁磁/半导体异质结材料的方法--物理气相沉积方法生长了一种铁磁/半导体异质结材料MnSb/Si.对所获得的样品进行特征X射线能谱分析表明Mn和Sb在Si衬底上的沉积速率相近,它们的原子百分数之比接近1∶1.X射线衍射分析发现薄膜中形成了MnSb相,样品在室温下测出磁滞回线也从侧面验证了存在MnSb相.用原子力显微镜对样品的表面进行观察,发现MnSb呈有规则形状的小晶粒状,晶粒大小比较均匀,尺寸大多数在500nm左右.     

铁磁/半导体异质结材料MnSb/Si的物理气相沉积生长

采用一种新的生长铁磁/半导体异质结材料的方法——物理气相沉积方法生长了一种铁磁/半导体异质结材料Mn Sb/Si.对所获得的样品进行特征X射线能谱分析表明Mn和Sb在Si衬底上的沉积速率相近,它们的原子百分数之比接近1∶1.X射线衍射分析发现薄膜中形成了Mn Sb相,样品在室温下测出磁滞回线也从侧面验证了存在Mn Sb相.用原子力显微镜对样品的表面进行观察,发现Mn Sb呈有规则形状的小晶粒状,晶粒大小比较均匀,尺寸大多数在5 0 0 nm左右.     

掺杂浓度对Co掺杂ZnO纳米棒的铁磁性的影响

采用化学气相沉积(CVD)方法制备出3种掺杂浓度的Co掺杂ZnO纳米棒。使用EDX(en-ergy dispersive X-ray)能谱,测得3种ZnO纳米棒中Co元素的掺杂浓度分别为0.4、1.4和2.4%。X射线衍射(XRD)分析表明,三个样品均为ZnO的六方铅锌矿结构,并沿着c轴取向择优生长。磁化曲线显示,掺杂浓度为0.4%的Co掺杂ZnO纳米棒为顺磁性,随着掺杂浓度的增大,Co掺杂ZnO纳米棒转变为铁磁性。扩展X射线吸收精细结构谱表明,Co掺杂ZnO纳米棒的铁磁性源于ZnO纳米棒中的Co金属团簇。     

ZnO纳米棒的制备与表征

近年来，一维纳米材料如纳米管、纳米线、纳米棒等由于在纳米电子器件和光电子器件中的潜在应用前景而吸引了众多科研小组的兴趣。ZnO纳米材料作为一种宽带系半导体，因其可以在各种高科技产品中的应用如光催化剂、气敏元件、光电二极管、变电阻等已引起人们广泛的研究，到现在为止，许多方法用来制备一维ZnO纳米材料，如电弧法、化学气相沉积、模板法和电化学沉积等。本文用溶液法合成ZnO纳米棒，并对其进行电子显微学的观察与表征。     

铝纳米薄膜对铜纳米薄膜的防护作用

铜纳米薄膜在微电子器件中应用广泛。然而,纳米尺度的铜表面极易发生氧化,影响铜纳米薄膜的电学性能。利用物理气相沉积方法制备了铜纳米薄膜,研究了基底粗糙度对铜纳米薄膜电学性能退化的影响,发现基底粗糙度越大,铜的电学性能退化越快。通过在铜纳米薄膜的表面蒸镀铝纳米薄膜对铜纳米薄膜进行防护,研究了铝纳米薄膜厚度对其在不同环境下防护效果的影响,结果显示铝膜厚度越大,对铜纳米薄膜的防护效果越好。通过高温破坏测试,发现铝纳米薄膜能有效地提高铜纳米薄膜的极限工作温度,当铝纳米薄膜厚度为10 nm时,可将铜纳米薄膜的极限工作温度提高2.5倍。     

聚焦电子束辐照原位制备单晶纳米棒

低维纳米材料相对于传统材料因其独特的物理化学性能已经成为研究热点。其制备方法主要有气相沉积法、电化学沉积法、模板法和聚焦电子束诱导沉积法等。所谓聚焦电子束诱导沉积法是指将电子束汇聚到几纳米区域的基材上，同时注入适当气氛，进而在基材上生成纳米线、纳米锥、纳米棒和纳米点等低纳纳米材料的方法。     

纳米金刚石薄膜的制背

采用微波等离子体化学气相沉积系统,利用氢气、甲烷、氩气和氧气为前驱气体,在直径为5 cm的(111)取向镜面抛光硅衬底上沉积出高平整度纳米金刚石薄膜.利用扫描电镜、X射线衍射谱和共焦显微显微拉曼光谱我们分析了薄膜的表面形貌和结构特征.该薄膜平均粒径约为20 nm.X射线衍射谱分析表明该薄膜具有立方相对称 (111)择优取向金刚石结构.在该薄膜一阶微显微拉曼光谱中,1 332 cm-1附近微晶金刚石的一阶特征拉曼峰减弱消失,可明显观测到的三个拉曼散射峰分别位于1 147 cm-1、1 364 cm-1和1 538 cm-1,与己报导的纳米金刚石拉曼光谱类似.该方法可制备出粒径约为20 nm粒度分布均匀致密具有较高含量的sp3键的纳米金刚石薄膜.     

ZnO纳米棒的电沉积生长方法研究

用含有硝酸锌(Zn(NO3)2)和六次甲基四胺(HMTA,C6H12N4)的电解液,在低温环境下采用阴极电沉积法在ITO玻璃上成功合成了氧化锌(ZnO)纳米棒阵列。系统研究了电压、前驱物(Zn2+)浓度、温度和种子层等参数对ZnO纳米棒形貌结构的影响,实现了ZnO纳米棒的可控制备。结果表明,在有种子层的情况下,当电压为-0.9V、Zn2+浓度为0.01M、温度为75℃条件下生长的ZnO纳米棒c-轴择优取向好、尺寸均匀(80~100nm),且在380~750nm的可见光波长范围内的透射率达到80%。     

溶液浓度对ZnO纳米棒形貌和发光的影响

为了获取高质量、高取向排列规则的ZnO纳米棒,玻璃衬底预先用脉冲激光沉积方法制备一层ZnO薄膜作为籽晶层,应用水热法在玻璃衬底上生长ZnO纳米棒。探究了籽晶层及不同溶液浓度对ZnO纳米棒结构和发光的影响,用扫描电子显微镜和X射线衍射仪测量样品的形貌和结构,用组建的光致发光测试系统对样品的室温光致发光光谱进行测定。结果表明,ZnO纳米棒具有高度取向且分布致密均匀;光致发光光谱显示ZnO的近带边发射比深能级发光略低;随着溶液浓度的增加,近带边发光和深能级发光相对强度的比值依次降低。     

Characteristic Length of Metallic Nanorods under Physical Vapor Deposition

By using physical vapor deposition (PVD) to grow metallic nanorods, the characteristic length is controllable, which can be identified by two different growth modes: Mode I and Mode II. In Mode I, the growth of metallic nanorods is dominated by the monolayer surface steps. Whereas in Mode II, the growth mechanism is mainly determined by the multilayer surface steps. In this work, we focused on the analysis of the physical process of Mode I, in which the adatoms diffuse on the monolayer surface at beginning, then diffuse down to the next monolayer surface, and finally result in the metallic nanorods growth. Based on the physical process, both the variations of the characteristic length and the numerical solutions were theoretically proposed. In addition, the two-dimensional (2D) lattice kinetic Monte Carlo simulations were employed to verify the theoretical derivation of the metallic nanorods growth. Our results pay a new way for modifying the performance of metallic nanorods-based applications and devices.     

Catalyst‐Free GaN Nanorods Synthesized by Selective Area Growth

GaN nanorod formation on Ga‐polar GaN by continuous mode metalorganic chemical vapor deposition selective area growth (MOCVD SAG) is achieved under a relatively Ga‐rich condition. The Ga‐rich condition, provided by applying a very low V/III ratio, alters the growth rates of various planes of the defined nanostructure by increasing relative growth rate of the semi‐polar tilted m‐plane {1–101} that usually is the slowest growing plane under continuous growth conditions. This increased growth rate relative to the non‐polar m‐plane {1–100} and even the c‐plane (0001), permits the formation of GaN nanorods with nonpolar sidewalls. In addition, a new growth mode, called the NH₃‐pulsed mode, is introduced, utilizing the advantages of both the continuous mode and the lower growth rate pulsed mode to form nanorods. Finally, nanorods grown under the different growth modes are compared and discussed.     

Fabrication Method,Ferromagnetic Resonance Spectroscopy and Spintronics Devices Based on the Organic-Based Ferrimagnet Vanadium Tetracyanoethylene

Organic-based magnetic materials have been used for spintronic device applications as electrodes of spin aligned carriers and spin-pumping substrates. Their advantages over more traditional inorganic magnets include reduced magnetic damping and lower fabrication costs. Vanadium tetracyanoethylene, V[TCNE]_x (x ≈ 2), is an organic-based ferrimagnet with an above room-temperature magnetic order temperature (T_c ≈ 400 K). V[TCNE]_x has deposition flexibility and can be grown on a variety of substrates via low-temperature chemical vapor deposition (CVD). A systematic study of V[TCNE]_x thin-film CVD parameters to achieve optimal film quality, reproducibility, and excellent magnetic properties is reported. This is assessed by broadband ferromagnetic resonance (FMR) that shows most narrow linewidth of ≈1.5 Gauss and an extremely low Gilbert damping coefficient. The neat V[TCNE]_x films are shown to be efficient spin injectors via spin pumping into an adjacent platinum layer. Also, under an optimized FMR linewidth, the V[TCNE]_x films exhibit Fano-type resonance with a continuum broadband absorption in the microwave range, which can be readily tuned by the microwave frequency.     

物理汽相生长并五苯晶体薄膜

用物理汽相沉积法在水平系统中生长有机半导体并五苯晶体薄膜.用10～30毫克的源生长出20～30 mm2大小的适合特性测量和器件制备的晶体薄膜.利用扫描电镜(SEM)、透射电镜(TEM)和X射线衍射仪(XRD)等仪器对并五苯晶体薄膜进行了测试分析.     

Well‐Aligned ZnO Nanorods via Hydrogen Treatment of ZnO Films

The formation of well‐aligned ZnO nanorods has been achieved via H₂ treatment of as‐grown ZnO films. Structural analyses reveal that the ZnO nanorods on the ZnO films are preferentially oriented along the c‐axis direction and exhibit a single‐crystalline wurtzite structure. To investigate the mechanism of formation of ZnO nanorods on the film, further H₂ treatment of the as‐grown ZnO nanorods was performed. Thinner and longer ZnO nanorods were obtained after certain periods of H₂ treatment. It is proposed that both etching and re‐deposition processes are taking place during the process, resulting in the aspect‐ratio enhancement of the ZnO nanorods and the formation of ZnO nanorods on the ZnO films. It is suggested that an appropriate concentration of the etching products remaining from the initial rod‐forming H₂ treatment allows subsequent re‐deposition of the ZnO nanorods with enhanced differentiation of the growth rates on the 〈001〉 and 〈100〉 crystal facets.     

电化学方法生长有序纳米柱阵列的发光性质

采用电化学方法在磁控溅射方法生长的ZnO薄膜上生长垂直于衬底排列的ZnO纳米柱.ZnO薄膜的作用主要是为ZnO纳米柱的生长提供同质外延层.电化学生长的ZnO纳米柱具有良好的晶体质量和发光性能.通过研究其变温发光光谱可以确定其紫外发光峰来自于带边激子的辐射复合.此种方法生长的ZnO纳米柱在场发射显示、蓝紫色和白光发光二极管方面有潜在的应用前景.     

氨化Si基Ga2O3/Co薄膜合成GaN纳米线及其表征

采用磁控溅射技术先在Si衬底上制备Ga2O3/Co薄膜,然后在950"C下流动的氨气中进行氨化反应制备GaN纳米棒.应用X射线衍射、扫描电镜、傅里叶红外吸收光谱、选区电子衍射和高分辨透射电子显微镜对样品进行表征.结果表明,采用此方法得到了六方纤锌矿结构的GaN单晶纳米棒.观察发现纳米棒表面光滑.并讨论了GaN纳米棒的生长机制.