Preparation of patterned boron nanowire films with different widths of unit-cell and their field emission properties

Large-area patterned films of boron nanowires(BNWs) are fabricated at various densities by chemical vapor deposition(CVD). Different widths of unit-cell of Mo masks are used as templates. The widths of unit-cell of Mo masks are100 μm, 150 μm, and 200 μm, respectively. The distance between unit cells is 50 μm. The BNWs have an average diameter of about 20 nm and lengths of 10 μm–20 μm. High-resolution transmission electron microscopy analysis shows that each nanowire has a β-tetragonal structure with good crystallization. Field emission measurements of the BNW films show that their turn-on electric fields decrease with width of unit-cell increasing.     

AuPd纳米粒子作为催化剂制备硼纳米线及其场发射性质

利用化学气相沉积法,采用不同组分的金属合金纳米粒子AuPd作为催化剂,在Si(111)基底上成功制备大面积、高密度的硼纳米线薄膜.纳米线的平均长度约为10μm,直径在50—130 nm之间.结构分析表明,纳米线为单晶结构,硼纳米线的直径随着元素Pd在合金催化剂中比例的增加而减少.场发射特性测试结果表明,通过调整催化剂组分可以实现对硼纳米线的尺寸和密度的调控.     

硼对沉积本征微晶硅薄膜特性的影响

采用甚高频等离子体增强化学气相沉积(VHF-PECVD)技术制备了不同腔室环境下的微晶硅薄膜.对单室沉积掺杂层p材料后遗留在腔室中的硼对本征微晶i材料电学特性和结构特性的影响进行了详细研究.测试结果表明：单室沉积p层后的硼降低了微晶i层材料的暗电导,增加了材料的光敏性;由于硼对i层污染程度的不同,使得材料的激活能发生了变化;腔室中残余的硼也导致微晶硅薄膜的结晶状况恶化,同时弱化了材料的(220)择优取向.而在较高功率和较强氢稀释下制备的晶化率较高,(220)晶向明显择优的材料受硼污染影响相对减小. 关键词： 单室 甚高频等离子体增强化学气相沉积 微晶硅 硼     

Magnetron sputtering synthesis of large area well-ordered boron nanowire arrays

The elemental boron and boron-rich compounds constitute a fascinating class of materials because of their vast variety of unique structures, extraordinary three-center electron-deficient bonds, and fascinating properties[1—4]. In general, they have an inverted molecular-like structure, which is characterized by three-dimensional skeletons of B12 icosahedra or icosahedral fragments. Furthermore, these B12 icosahedra are linked together by two-center covalent bonds, which lead to the intra-clus…     

衬底对化学气相沉积法制备氧化硅纳米线的影响

通过化学气相沉积法在不同衬底上制备了大量的氧化硅纳米线.选用衬底为Si片、带有约100nm厚SiO2氧化层Si片和石英片.利用场发射扫描电子显微镜(SEM)和透射电镜(TEM，配备有能谱仪)对样品的表面形貌、结构和成分进行研究.结果表明：这些纳米线都为非晶态，但在不同衬底上生长的纳米线形貌、尺寸和化学成分不同.讨论了各种衬底对不同特征氧化硅纳米线生长的影响. 关键词： 化学气相沉积 纳米线 纳米颗粒     

微波等离子体化学气相沉积方法在Si衬底上生长SiC纳米线

应用微波等离子体化学气相沉积方法,在单晶Si(100)衬底上生长出SiC纳米线.应用扫描电子显微镜、透射电子显微镜、能量损失谱(EDS)和选区电子衍射(SAD)等方法对纳米线化学组成和结构进行了分析和表征.给出该纳米线的生长机理 关键词： 微波等离子体化学气相沉积 SiC纳米线 生长机理     

Synthesis,structural and ellipsometric evaluation of oxygen-deficient and nearly stoichiometric zinc oxide and indium oxide nanowires/nanoparticles

Oxygen-deficient (OD) and nearly stoichiometric (NST) ZnO and In₂O₃ nanowires/nanoparticles were synthesized by chemical vapor deposition on Au-coated silicon substrates. The OD ZnO and OD In₂O₃ nanowires were synthesized at 750 and 950°C, respectively, using Ar flow at ambient pressure. A mixture of flowing Ar and O₂ was used for synthesizing NST ZnO nanowires and NST In₂O₃ nanoparticles. Growth of OD ZnO nanowires and NST In₂O₃ nanoparticles was found to be via a vapor–solid (VS) mechanism and the growth of NST ZnO nanowires was via a vapor–liquid–solid mechanism (VLS). However, it was uncertain whether the growth of OD In₂O₃ nanowires was via a VS or VLS mechanism. The optical constants, thickness and surface roughness of the prepared nanostructured films were determined by spectroscopic ellipsometry measurements. A three-layered model was used to fit the calculated data to the experimental ellipsometric spectra. The refractive index of OD ZnO, NST ZnO nanowires and NST In₂O₃ nanoparticles films displayed normal dispersion behavior. The calculated optical band gap values for OD ZnO, NST ZnO, OD In₂O₃ nanowires and NST In₂O₃ nanoparticles films were 3.03, 3.55, 2.81 and 3.52?eV, respectively.     

高取向As掺杂ZnO纳米线阵列的制备与表征

在不采用任何金属催化剂的条件下,运用化学气相沉积法,在Si(100)衬底上制备出高取向的As掺杂ZnO纳米线阵列.样品的X射线衍射(XRD)谱显示获得了单一取向的衍射峰,表明样品具有较好的结晶质量.场发射扫描电镜(FE-SEM)观察表明,As掺杂ZnO纳米线阵列具有均一的直径和长度,其顶部和根部直径分别为70 nm和1...     

掺杂金刚石薄膜的缺陷研究

利用多普勒增宽谱和电子顺磁共振研究了掺硼和掺硫金刚石薄膜的缺陷状态.多普勒增宽谱的结果表明，不同杂质元素掺杂的金刚石薄膜，其中使正电子湮没的缺陷种类是相同的；正电子与不同杂质元素硼、硫之间的相互作用不明显；少量硼可使金刚石膜中的空位浓度减少.EPR结果表明，各掺杂样品的顺磁信号主要来自于金刚石的碳悬键. 关键词： 金刚石 掺杂 多普勒增宽谱 电子顺磁共振     

MOCVD法制备BGaN薄膜

利用金属有机物化学气相沉积(MOCVD)技术,在蓝宝石衬底上进行了BGaN薄膜的外延生长,研究了生长厚度、温度、压力和B/Ⅲ比等条件对BGaN薄膜中B组分的影响。X射线衍射测试结果表明,降低生长温度、压力以及增加B/Ⅲ比,更有利于提高BGaN薄膜中B的并入效率。在800℃、30 kPa及B/Ⅲ比为30%的生长条件下,制备的BGaN薄膜中B组分最高,为6.1%。     

MOCVD自催化法在Si(100)衬底上生长InP/InGaAs核壳结构纳米线

采用自催化法,利用金属有机化学气相沉积技术,在Si(100)衬底上成功制备了InP/InGaAs核壳结构纳米线。通过扫描电子显微镜观察纳米线形貌,在核壳结构纳米线的顶端催化剂转化成了颗粒状晶体。利用X射线衍射和透射电子显微镜研究了InP纳米线上生长InGaAs外壳的过程,并应用X射线能量色散能谱仪对纳米线顶端进行了轴向和径向的线扫描,得到了纳米线上元素组分分布。催化剂的转化发生在制备InGaAs壳之前的升温过程中,且形成的晶体中含有合金成分。InGaAs壳的组分调整可以通过改变生长过程中生长源气体的流量来实现。     

等离子体增强化学气相沉积法实现硅纳米线掺硼

用等离子体增强化学气相沉积(PECVD)方法成功实现硅纳米线的掺B.选用Si片作衬底，硅烷 （SiH4）作硅源，硼烷（B2H6）作掺杂气体， Au作催化剂，生长温度440℃.基于气-液-固(VLS)机制，探讨了掺B硅纳米线可能的生长机制.PECVD法化学成分配比更灵活，更容易实现纳米线掺杂，进一步有望生长硅纳米线pn结，为研制纳米量级器件提供技术基础. 关键词： 硅纳米线 化学气相沉积 纳米器件     

Selective formation of silicon nanowires on pre-patterned substrates

In this paper, the selective growth of silicon nanowires (SiNWs) was studied. With the aid of photolithography, the vertically aligned silicon nanowires were selectively formed on the patterned substrates via an electroless metal deposition (EMD) method under normal conditions (room temperature, 1 atm). Low-pressure chemical vapor deposition (LPCVD) silicon nitride was used as the masking layer for SiNWs preparation. The scanning electron microscope was used to examine the etching results. Both the patterned and the unpatterned silicon substrates were used for study. The results indicated that the growth rates of the SiNWs upon the patterned and the unpatterned substrates are different. For the patterned substrates, the growth rate of SiNWs is dependent upon the pattern shape. The influence of length-to-width ratio for the rectangular-shaped patterns was studied. It is concluded that by designing the proper length-to-width ratio, the nanowires with different lengths can be fabricated simultaneously on the same substrate.     

硅纳米线的PEOVD生长研究

本文以硅烷（SiH4）为反应气体,利用等离子体化学气相沉积（PECVD）方法在硅（100）衬底上生长硅纳米晶体、纳米线。应用扫描电镜观察不同条件下生长的样品表面,发现衬底条件对硅纳米结构的影响十分显著。在温度、压强等其它条件相同的情况下,对硅衬底应用Fe^3＋催化剂处理后,呈纳米线状结构生长,而无Fe催化剂涂覆情况下,基本呈纳米晶体状生长,说明催化剂对si纳米线的生成起了重要的促进生长作用。通过进一步研究硅纳米晶体、纳米线的等离子增强化学气相生长机理,发现它们以气-液-固（VLS）机制生长。     

Room-temperature ferromagnetism observed in Nd-doped In_2O_3 dilute magnetic semiconducting nanowires

Nd-doped In_2O_3 nanowires were fabricated by an Au-catalyzed chemical vapor deposition method.Nd atoms were successfully doped into the In_2O_3 host lattice structure,as revealed by energy dispersive x-ray spectroscopy,x-ray photoelectron spectroscopy,Raman spectroscopy,and x-ray diffraction.Robust room temperature ferromagnetism was observed in Nd-doped In_2O_3 nanowires,which was attributed to the long-range-mediated magnetization among Nd~(3+)-vacancy complexes through percolation-bound magnetic polarons.     

立方氮化硼薄膜的生长特性与粘附性研究

用X射线衍射技术、红外吸收光谱、扫描电子显微镜、X射线光电子能谱对热丝辅助射频等离子体化学汽相沉积法制备的立方氮化硼(c-BN)薄膜的生长特性和粘附性进行了研究.改变生长条件，在Si、不锈钢和Ni衬底上沉积c-BN薄膜，进而研究了c-BN薄膜的质量和生长条件与衬底之间的关系.实验发现，Ni衬底上生长的薄膜c-BN含量较高，且粘附性好.当Si衬底上溅射一层Ni过渡层，再生长c-BN薄膜，薄膜中c-BN含量提高，与Si衬底的粘附性也显著增强. 关键词：     

Fabrication of particular structures of hexagonal boron nitride and boron–carbon–nitrogen layers by anisotropic etching

Anisotropic etching of hexagonal boron nitride (h-BN) and boron–carbon–nitrogen (BCN) basal plane can be an exciting platform to develop well-defined structures with interesting properties. Here, we developed an etching process of atomically thin h-BN and BCN layers to fabricate nanoribbons (NRs) and other distinct structures by annealing in H₂ and Ar gas mixture. BCN and h-BN films are grown on Cu foil by chemical vapor deposition (CVD) using solid camphor and ammonia borane as carbon, nitrogen and boron source, respectively. Formation of micron size well-defined etched holes and NRs are obtained in both h-BN and BCN layers by the post growth annealing process. The etching process of h-BN and BCN basal plane to fabricate NRs and other structures with pronounced edges can open up new possibilities in 2D hybrid materials.     

化学气相沉积-后退火法制备MgB2超导薄膜

本文提出在高真空镀膜系统中通过化学气相沉积(CVD)的方法沉积高纯度的先驱B膜,再经过后退火工艺,Mg扩散进入先驱膜而反应生成了MgB2超导薄膜.经过多种实验方法检测,这种薄膜具有较为优异的超导性能,是一种和传统微电子工艺兼容、适宜于工业化大规模生产MgB2超导薄膜的方法.     

Catalyst-free growth of well-aligned arsenic-doped ZnO nanowires by chemical vapor deposition method

ZnO nanowires with different arsenic concentration were grown on Si (1 0 0) substrates by chemical vapor deposition method without using catalyst. Zn/GaAs mixed powders were used as Zn and As source, respectively. Oxygen was used as oxidant. The images of scanning electron microscope show that the arsenic-doped ZnO nanowires with preferred c-axial orientation were obtained, which is in well accordance with the X-ray diffraction analysis. The arsenic related acceptor emission was observed in the photoluminescence spectra at 11 K for all arsenic-doped ZnO samples. This method for the preparation of arsenic-doped ZnO nanowires may open the way to realize the ZnO nanowires based light-emitting diode and laser diode.     

Horizontal InAs nanowire transistors grown on patterned silicon-on-insulator substrate

High-density horizontal InAs nanowire transistors are fabricated on the interdigital silicon-on-insulator substrate. Hexagonal InAs nanowires are uniformly grown between face-to-face (111) vertical sidewalls of neighboring Si fingers by metal-organic chemical vapor deposition. The density of InAs nanowires is high up to 32 per group of silicon fingers, namely an average of 4 nanowires per micrometer. The electrical characteristics with a higher on/off current ratio of 2×10⁵ are obtained at room temperature. The silicon-based horizontal InAs nanowire transistors are very promising for future high-performance circuits.