373 resultados para ZnO nanobelts
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ZnO films were deposited on Si(100) substrates at 300℃ by metal - organic chemical vapor deposition(MOCVD). The effect of different ratios of DEZn to N2O on crystal quality was analyzed. It is found that the optimum ratio of DEZn to N2O is 2.1. And in this optimum growth condition, X - ray diffraction (XRD) and scanning probe morphology (SPM) images indicate that the films grow along the c - axis orientation. ZnO film exhibits a strong UV optical absorption near 388 nm. And the optical absorbance is close to zero,that indicates nearly 100% optical transparence. Photoluminescence (PL) spectrum shows only strong near - band - edge emissions with little or no deep - level emission related to defects. The full - width at half - maximum (FWHM) of the ultraviolet emission peak is 80meV. The results indicate that better crystal quality can be obtained.
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利用化学气相传输法生长了ZnO单晶.通过控制源区和生长端的温度梯度,使用碳辅助增强质量传尊挚应,在无籽晶自发成核的条件下,得到了晶粒尺寸达5mm×8mm的ZnO晶体.利用长有GaN层的蓝宝石号片待为籽晶,得到了直径32mm、厚4mm左右的ZnO单晶体.用光致发光谱和X射线双晶衍射研究了ZnO晶体的性质并对生长的热力学过程和现象进行了分析.
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用脉冲激光沉积(PLD)方法在Si(111)衬底上制备了ZnO薄膜。以325nmHe-Cd激光器为光源对薄膜进行了荧光光谱分析,用X射线衍射仪(XRD)和原子力显微镜(AFM)分别对薄膜的结构和形貌进行了分析。脉冲激光沉积方法的主要生长参量为氧压、激光重复频率、生长温度和激光能量。通过控制这些参量变量,研究了这些参量对ZnO薄膜发光特性的影响,得到了用于紫外发光的ZnO薄膜生长的优化条件
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利用慢正电子研究了不同氧含量时射频磁控反应溅射制备的ZnO样品,观察到ZnO中本征缺陷(Vo,VZn)随混合气体中O2比例(PO2)的变化关系.结果表明
Resumo:
High quality ZnO films are successfully grown on Si(100) substrates by metal-organic chemical vapor deposition at 300℃. The effects of the thickness of the ZnO films on crystal structure, surface morphology,and optical properties are investigated using X-ray diffraction, scanning probe microscopy,and photoluminescence spectra, respectively. It is shown that the ZnO films grown on Si substrates have a highly-preferential C-axis orientation,but it is difficult to obtain the better structural and optical properties of the ZnO films with the increasing of thickness. It is maybe due to that the grain size and the growth model are changed in the growth process.
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利用X射线衍射(XRD),X射线摇摆曲线(XRC)和X射线光电子能谱(XPS)分析方法对氧离子束辅助激光淀积生长的ZnO/Si异质结薄膜进行了分析.结果表明:用该法可生长出高度c轴单一取向ZnO薄膜,XRC的半高宽度(FWHM)仅为2.918°.表明此生长方法经优化,可生长出单晶质量很好的ZnO/Si薄膜.
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ZnO是一种重要的功能材料和新型的n一Ⅵ族宽禁带半导体材料。采用溶胶一凝胶(sol-gel)工艺在si(100)、si(111)和c面蓝宝石衬底上成功制备出高质量的ZnO纳米薄膜,并用XRD、SEM、AFM等方法研究了薄膜的特性。首次以制备的ZnO纳米薄膜为缓冲层,在n型si(1()o)衬底上采用低压化学气相沉积(LPCVD)工艺外延生长了SiC薄膜,得到了低载流子浓度、高电子迁移率和高空穴迁移率的两种SiC薄膜样品,分析了该薄膜的性能。
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用真空蒸发法在玻璃和单晶硅片上制备纯Zn和掺杂Zn薄膜,然后在高于450 ℃条件下进行氧化、热处理(玻璃衬底)获得良好的纳米ZnO薄膜和掺杂ZnO薄膜。对单晶硅衬底上制备的纯Zn薄膜在高于800 ℃温度条件下进行液态源掺杂,获得掺B和P纳米ZnO薄膜。实验表明,掺杂和热处理使纳米ZnO薄膜的结构、导电性能得到改善,有效地降低了纳米ZnO薄膜的电阻,同时薄膜的气敏特性也得到较大的改善。
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用光致发光的方法研究了掺铽的ZnO纳米晶这种新型掺杂纳米晶体系,观察到了其中的协同发光现象,指出ZnO纳米基质与掺入其中的铽中心之间存在有效的能量传递。该能量传递对稀土铽离子的特征发光起决定性的作用。
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采用常规磁控溅射方法,通过优化工艺,在Si(100),Si(111)多种基片上沉积ZnO薄膜。利用透射电镜(TEM)、X射线衍射(XRD)和X射线摇摆曲线(XRC),对ZnO薄膜的微区形貌、结晶情况、C轴择优取向进行了详细的测试分析。结果表明,所制备的ZnO薄膜具有理想的结构特性,大多数样品测得ZnO(002)晶面XRC的半高宽(FWHM)1°左右,最小值达0.353°,优于目前国内外同类研究的最佳结果2°。并对ZnO/Si(100)与ZnO/Si(111)衬底的结果进行了比较和讨论。
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室温下在p-Si(100)上采用直流反应磁控溅射法外延生长了ZnO薄膜。XRD测量表明了ZnO是高度c轴单一取向生长的,XRC测量则表明了ZnO的高质量。在室温下的PL测量中见到了带边发射,其强度与晶体质量有关。
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在玻璃基底踌地基底上用反应式直流磁控溅射法制备了ZnO薄膜。用AES和XRD对薄膜结构和组分进行测试,结果表明,五种基底上生长的ZnO薄膜在不同程度上都具有优良的纵向均匀性、明显的c轴择优取和向较高的结晶度,而硅基底上薄膜的结构普遍优于玻璃基底上沉积薄膜。
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利用X射线光电子能谱深度剖析方法对ZnO/Si异质结构进行了分析。用该法可生长出正化学比的ZnO,不过生长的ZnO薄膜存在孔隙,工艺还有待进一步改进。
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于2010-11-23批量导入
Microstructural and compositional characteristics of GaN films grown on a ZnO-buffered Si(111) wafer
Resumo:
Polycrystalline GaN thin films have been deposited epitaxially on a ZnO-buffered (111)-oriented Si substrate by molecular beam epitaxy. The microstructural and compositional characteristics of the films were studied by analytical transmission electron microscopy (TEM). A SiO2 amorphous layer about 3.5 nm in thickness between the Si/ZnO interface has been identified by means of spatially resolved electron energy loss spectroscopy. Cross-sectional and plan-view TEM investigations reveal (GaN/ZnO/SiO2/Si) layers exhibiting definite a crystallographic relationship: [111](Si)//[111](ZnO)//[0001](GaN) along the epitaxy direction. GaN films are polycrystalline with nanoscale grains (similar to100 nm in size) grown along [0001] direction with about 20degrees between the (1 (1) over bar 00) planes of adjacent grains. A three-dimensional growth mode for the buffer layer and the film is proposed to explain the formation of the as-grown polycrystalline GaN films and the functionality of the buffer layer. (C) 2004 Elsevier Ltd. All rights reserved.