In2O3纳米线制备及其特性

使用管式加热炉成功地制备出In2O3纳米线.通过扫描电子显微镜可以看到样品为In2O3纳米线;X射线衍射分析证实该材料是立方结构的In2O3;X射线光电子谱分析发现该In2O3中存在大量氧缺陷;光致发光谱研究显示制得的In2O3纳米线有比较强的发光现象,主要集中在紫外光谱区.同时对反应的气相-固相(V-S)生长机理和In2O3的光致发光机理进行了详细分析.     

多重气固反应制备一维SiC纳米线

以硅片、石墨和SiO2粉末为原料,通过多重气固反应成功地制备出一维SiC纳米线. X射线衍射仪分析表明生成产物为立方结构的β-SiC. 利用扫描电子显微镜、透射电子显微镜和高分辨透射电子显微镜(HRTEM)观察,该一维SiC纳米线的直径为30~50nm,长度可达几十甚至上百微米,为沿［111］方向生长的单晶β-SiC纳米线. 根据多次对比实验的结果,由多重气固(VS)反应提出了该方法制备SiC纳米线的生长机理.     

多重气固反应制备一维SiC纳米线

以硅片、石墨和SiO2粉末为原料,通过多重气同反应成功地制备出一维SiC纳米线.X射线衍射仪分析表明生成产物为立方结构的β-SiC.利用扫描电子显微镜、透射电子显微镜和高分辨透射电子显微镜(HRTEM)观察,该一维SiC纳米线的直径为30～50nm,长度可达几十甚至上百微米,为沿[111]方向生长的单晶β-SiC纳米线.根据多次对比实验的结果,由多重气固(VS)反应提出了该方法制备SiC纳米线的生长机理.     

高质量氮化镓纳米线的结构表征

本文采用CVD法,以甩涂在衬底硅片上的Ga2O3薄膜和NH3作为原料,成功制备出大量GaN纳米线。采用X射线衍射仪（XRD）、场发射扫描电镜（FESEM）、能量色散谱仪（EDS）和高分辨透射电镜（HRTEM）对样品进行了成分和结构分析,并简单讨论了其生长机理。结果表明：产物为平直光滑的GaN纳米线,其直径为30nm-50nm。长度可达几十微米,纳米线为高质量的六方纤锌矿GaN晶体。     

Si基氨化ZnO/Ga2O3薄膜制备GaN纳米线

利用射频磁控溅射法在Si(111)衬底上溅射ZnO中间层和Ga2O3薄膜,然后在管式炉中常压下通氨气对ZnO/Ga2O3薄膜进行氨化,高温下ZnO层在氨气气氛中挥发,而Ga2O3薄膜和氨气反应合成出GaN纳米线.X射线衍射测量结果表明利用该方法制备的GaN纳米线具有沿c轴方向择优生长的六角纤锌矿结构.利用扫描电子显微镜、透射电子显微镜、傅里叶红外透射谱、能量弥散谱及选区电子衍射观测并分析了样品的形貌、成分和晶格结构.研究发现ZnO层的挥发有利于Ga2O3和NH3反应合成GaN纳米线.     

硅纳米线的合成及表征

目前已通过气-液-固生长机理及氧化物辅助生长等机理合成了大量硅纳米线,电镜、能量色散X射线分析、X射线光电子能谱、拉曼光谱、近边X射线吸收精细结构光谱、I-V测量、光致发光、场发射、电子输运测量等是表征硅纳米线的有效手段,介绍了硅纳米线在合成及表征方面的最新进展,并对其发展做了展望.     

Si基氨化ZnO／Ga2O3薄膜制备GaN纳米线

利用射频磁控溅射法在Si(111)衬底上溅射ZnO中间层和Ga2O3薄膜，然后在管式炉中常压下通氨气对ZnO/Ga2O3薄膜进行氨化，高温下ZnO层在氨气气氛中挥发，而Ga2O3薄膜和氨气反应合成出GaN纳米线．X射线衍射测量结果表明利用该方法制备的GaN纳米线具有沿c轴方向择优生长的六角纤锌矿结构．利用扫描电子显微镜、透射电子显微镜、傅里叶红外透射谱、能量弥散谱及选区电子衍射观测并分析了样品的形貌、成分和晶格结构．研究发现ZnO层的挥发有利于Ga2O3和NH3反应合成GaN纳米线．     

钯缓冲层制备GaN纳米线及光学特性分析

利用射频磁控技术,在Si衬底上以Pd为缓冲层、Ga2O3粉末作为生长GaN的Ga源,成功制备出大量GaN纳米线。通过扫描电子显微镜、透射电子显微镜和高分辨透射电子显微镜观察分析得出GaN纳米线为单晶结构,纳米线的直径为10～60nm,长度达几十个微米。X射线衍射和X射线能量散射谱显示合成的纳米线为GaN单晶结构。傅里叶变换红外吸收光谱和光致发光光谱测试表明,制得的GaN纳米线与GaN体材料相比具有不同的光学特性。     

氧化铝模板法制备Ge纳米线

采用氧化铝模板法结合具有高真空背景的低压化学气相沉积技术制备出 Ge纳米线 .在氧化铝模板的背面喷金作为催化剂 ,合成了 Ge纳米线 .采用原子力显微镜、X射线衍射、透射电镜、能量散射谱等手段对 Ge纳米线进行了分析 .Ge纳米线的直径约为 30 nm,长度超过 6 0 0 nm.对 Ge纳米线的生长机理进行了探讨 .     

氧化铝模板法制备Ge纳米线

采用氧化铝模板法结合具有高真空背景的低压化学气相沉积技术制备出Ge纳米线.在氧化铝模板的背面喷金作为催化剂,合成了Ge纳米线.采用原子力显微镜、X射线衍射、透射电镜、能量散射谱等手段对Ge纳米线进行了分析.Ge纳米线的直径约为30nm,长度超过600nm.对Ge纳米线的生长机理进行了探讨.     

High Purity and Large-scale Preparation of β-Ga2O3 Nanowires and Nanosheets by CVD and Their Raman and Photoluminescence Characteristics

Ga2O3 nano-structures,nanowires and nanosheets are produced on Au pre-coated(111) silicon substrates with chemical vapor deposition(CVD) technique.By evaporating pure Ga powder in the H2O atmosphere under ambient pressure the large-scale preparation of β-Ga2O3 with monoclinic crystalline structure is achieved.The crystalline structures and morphologies of produced Ga2O3 nano-structures are characterized by means of scanning electron microscope(SEM),X-ray diffraction(XRD),selected area electron diffraction(SAED) and transmission electron microscope(TEM).Raman spectrum reveals the typical vibration modes of Ga2O3.The vibration mode shifts corresponding to Ga2O3 nano-structures are not found.Two distinguish photoluminescence(PL) emissions are found at about 399 nm and 469 nm owing to the VO-VGa excitation and VO-VGa-O excitation,respectively.The growth mechanisms of Ga2O3 nanowires and nanosheets are discussed with vapor-liquid-solid(VLS) and vapor-solid(VS) mechanisms.     

High Purity and Large-scale Preparation of β-Ga2O3 Nanowires and Nanosheets by CVD and Their Raman and Photoluminescence Characteristics

Ga2O3 nano-structures, nanowires and nanosheets are produced on Au pre coated（111） silicon substrates with chemical vapor deposition（CVD） technique. By evaporating pure Ga powder in the H2O atmosphere under ambient pressure the large-scale preparation of β-Ga2O3 with monoclinic crystalline structure is achieved. The crystalline structures and morphologies of produced Ga2O3 nano-structures are characterized by means of scanning electron microscope（SEM）, X-ray diffraction（XRD）, selected area electron diffraction （SAED） and transmission electron microscope（TEM）. Raman spectrum reveals the typical vibration modes of Ga2O3 The vibration mode shifts corresponding to Ga2O3 nano-structures are not found. Two distinguish photoluminescence（PL） emissions are found at about 399 nm and 469 nm owing to the VO-VGa excitation and VO-VGaO excitation, respectively. The growth mechanisms of Ga2O3 nanowires and nanosheets are discussed with vapor liquid-solid（VLS） and vapor-solid（VS） mechanisms.     

Synthesis and Photoluminescence of GaN Nanowires with Nb Catalyst

Large-scale GaN nanowires are successfully synthesized by ammoniating Ga2O3 films on Nb layer deposited on Si（111） substrates at 850 ℃. X-ray diffraction （XRD）, scanning electron microscopy （SEM）, field-emssion transmission electron microscope（FETEM）, Fourier transformed infrared spectrum（FTIR） are used to characterize the structural and morphological properties of the as-synthesized GaN nanowires. The results reveal that the nanowires are pure hexagonal GaN wurtzite structure with a length of about several microns and a diameter between 50 nm and 100 nm. Finally, discussed briefly is the formation mechanism of gallium nitride nanowires.     

氧化物缓冲层制备Si(111)基GaN纳米线

采用氧化物缓冲层,通过射频磁控溅射系统依次在n型Si(111)衬底上沉积Ga2O3/ZnO(Ga2O3/MgO)薄膜,然后将薄膜于950℃氨化合成GaN纳米结构,氨化时间为15min。采用X射线衍射(XRD)、傅里叶红外吸收谱(FTIR)和高分辨透射电镜(HRTEM)对样品的结构进行了分析,结果显示两种缓冲层下制备的样品均为六方纤锌矿单晶GaN纳米结构,且缓冲层的取向对纳米线的生长方向有很大影响;采用扫描电镜(SEM)对样品的形貌进行了测试,发现纳米线表面光滑,长度可达几十微米,表明采用氧化物缓冲层制备了高质量的GaN线。同时对GaN纳米线的生长机理进行了简单讨论。     

氨化Ga2O3/Mg薄膜制备簇状GaN纳米线

通过在1050°C时氨化Ga2O3/Mg薄膜制备出簇状GaN纳米线。用X射线衍射(XRD),傅里叶红外吸收光谱(FTIR)扫描电子显微镜(SEM)和高分辨电子显微镜(HRTEM)对样品进行测试分析。结果表明,GaN纳米线为六万纤锌矿结构单晶相并且成族生长,直径在200～500nm米左右,其长度可达5～10μm。几乎所有纳米线的直径均有逐渐缩小的趋势。对Mg膜的作用进行了初步的分析。     

Formation of GaN Nanowires by Ammoniating Ga2O3 Films Deposited on Oxidized Al Layers on Si Substrate

Large quantities of gallium nitride（GaN） nanowires have been prepared via ammoniating the Ga2O3 films deposited on the oxidized aluminum layer at 950℃ in a quartz tube. The nanowires have been confirmed as crystalline wurtzite GaN by X-ray diffraction, X-ray photoelectron spectrometry scanning electron microscope and selected-area electron diffraction. Transmission electron microscope （TEM） and scanning electron microscopy（SEM） reveal that the nanowires are amorphous and irregular, with diameters ranging from 30 nm to 80 nm and lengths up to tens of microns. Selected-area electron diffraction indicates that the nanowire with the hexagonal wurtzite structure is the single crystalline. The growth mechanism is discussed briefly.     

From Mesostructured Wurtzite ZnS‐Nanowire/Amine Nanocomposites to ZnS Nanowires Exhibiting Quantum Size Effects: A Mild‐Solution Chemistry Approach

Mesostructured wurtzite ZnS‐nanowire‐bundle/amine nanocomposites displaying remarkable quantum size effects are synthesized by using a mild‐solution reaction using different amines, such as n‐butylamine, ethylamine, and tetraethylenepentamine, Zn(NO₃)₂·6 H₂O, and CS(NH₂)₂ or Na₂S·9 H₂O as the precursors at temperatures ranging from room temperature to 180 °C. A possible mechanism for the shape‐controlled growth of ZnS nanowires and nanocomposites is proposed. Increasing the reaction temperature or dispersing the composite in acetic acid or NaOH solution leads to the destruction of the periodic structure and the formation of individual wurtzite nanowires and their aggregates. The nanowire/amine composites and individual wurtzite nanowires both display obvious quantum size effects. Strong band‐edge emission is observed for the wurtzite ZnS nanowires after removal of the amine. The optical properties of these nanocomposites and nanowires are strongly related to the preparation conditions and can be finely tuned. This technique provides a unique approach for fabricating highly oriented wurtzite ZnS semiconductor nanowires, and can potentially be extended to other semiconducting systems.     

Semiconductor nanowires surrounded by cylindrical Al2O3 shells

The GaN, GaP, InP, Si₃N₄, SiO₂/Si, SiC, and ZnO semiconductor nanowires were synthesized by a variety of growth methods, and they were wrapped cylindrically with amorphous aluminum oxide (Al₂O₃) shells. The Al₂O₃ was deposited on these seven different semiconductor nanowires by atomic layer deposition (ALD) at a substrate temperature of 200°C using trimethylaluminum (TMA) and distilled water (H₂O). Transmission electron microscopy (TEM) images taken for the nanowires revealed that Al₂O₃ cylindrical shells surround uniformly all these semiconductor nanowires. Our TEM study illustrates that the ALD of Al₂O₃ has an excellent capability to coat any semiconductor nanowires conformally; its coating capability is independent of the chemical component, lattice structure, and growth direction of the nanowires. This study suggests that the ALD of Al₂O₃ on nanowires is one of the promising methods to prepare cylindrical dielectric shells in coaxially gated, nanowire field-effect transistors (FETs).     

氧化镓纳米带的制备研究

纳米带是继纳米线、纳米管之后 ,最新报道的又一种准一维纳米结构。文中介绍了 Ga2 O3纳米带制备的新方法。这种方法与首次报道的纳米带的生长方法有很大不同。用扫描电子显微镜和透射电子显微镜对产物形貌进行了分析 ,纳米带宽约 5 0 0 nm,厚度约 1 0 nm,宽度 /厚度比大于 2 0。选区电子衍射 (SAED)分析表明 ,产物是纯净的 Ga2 O3单晶。实验还发现了一些特殊形态的纳米结构 ,如纳米片等 ,证明了纳米带是一种常见并稳定存在的形态。最后 ,根据实验现象对纳米带的生长机制进行了初步的分析与讨论。