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1.
采用脉冲激光沉积(PLD)法在单晶Si(100)衬底上生长ZnO薄膜,以X射线衍射(XRD)、原子力显微镜(AFM)和透射电镜(TEM)等手段分析了所得ZnO薄膜的晶体结构和微观形貌。优化工艺(700℃,20Pa)下生长的ZnO薄膜呈c轴高度择优取向,柱状晶垂直衬底表面生长,结构致密均匀。室温光致发光(PL)谱分析结果表明,随着薄膜生长时O2分压的增大,近带边紫外发光峰与深能级发光峰之比显著增强,表明薄膜的结晶性能和化学计量比都有了很大的改善。O2分压为20Pa时所生长的ZnO薄膜具有较理想的化学计量比和较高的光学质量。 相似文献
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ZnO薄膜的分子束外延生长及性能 总被引:2,自引:0,他引:2
利用分子束外延(MBE)和氧等离子体源辅助MBE方法分别在Si(100)、GaAs(100)和蓝宝石Al2O3(0001)衬底上用Zn、ZnS或以一定Zn-O化学计量比作缓冲层,改变衬底生长温度和氧压,并在氧气氛下,进行原位退火处理,得到ZnO薄膜。依据X射线衍射(XRD)图,表明样品的结晶性能尚好,且呈c轴择优取向;实验结果表明在不同衬底上生长的ZnO薄膜,由于晶格失配度不同,其衍射峰也有区别。用原子力显微镜(AFM)观测薄膜的表面形貌,为晶粒尺寸约几十纳米的ZnO纳米晶,且ZnO晶粒呈六边形柱状垂直于衬底的表面。采用掠入射X射线反射率法测膜厚。在360nm激发下,样品的发光光谱是峰值为410,510nm的双峰谱,是与样品表面氧缺陷有关的深能级发光。 相似文献
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不同衬底温度下PLD法制备的氧化锌薄膜的特性 总被引:1,自引:1,他引:0
利用GCR-170型脉冲激光器Nd:YAG的三次谐波(355nm),以蓝宝石Al2O3(0001)为衬底,在不同温度下采用脉冲激光沉积法制备了ZnO薄膜.通过原子力显微镜、Raman谱、光致发光谱、红外透射谱、霍尔效应和表面粗糙度分析仪对制备的ZnO薄膜进行了测试.分析了在不同衬底温度下薄膜的表面形貌、光学特性,同时进行了薄膜结构和厚度的测试.研究表明:衬底温度对ZnO薄膜的表面形貌、光学特性、结构特性都是重要的工艺参量,尤其在500℃时沉积的ZnO薄膜致密均匀,并表现出较强的紫外发射峰. 相似文献
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脉冲激光沉积方法制备ZnO薄膜生长参量对发光特性的影响 总被引:4,自引:3,他引:1
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:发现在温度为650℃左右、氧压50Pa左右、频率5Hz左右的范围内能得到半峰全宽较窄,强度较大的紫外发光峰。分析认为紫外峰主要是由激子辐射复合发光形成的,绿光带主要和Ozn的存在密切相关,氧空位是蓝光发射的重要原因。 相似文献
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采用反应射频磁控溅射方法,在Si (100) 基片上制备了具有高c轴择优取向的ZnO薄膜.利用 原子力显微镜、透射电子显微镜、X射线衍射分析、拉曼光谱等表征技术,研究了沉积温度 对ZnO薄膜的表面形貌、晶粒尺度、应力状态等结晶性能的影响;通过沉积温度对透射光谱 和光致荧光光谱的影响,探讨了ZnO薄膜的结晶特性与光学性能之间的关系.研究结果显示, 在室温至500℃的范围内,ZnO薄膜的晶粒尺寸随沉积温度的增加而增加,在沉积温度为500 ℃时达到最大;当沉积温度为750℃时,ZnO薄膜的晶粒尺度有所减小;在室温至750℃的范 围内,薄膜中ZnO晶粒与Si基体之间均存在着相对固定的外延关系;在沉积温度低于500℃时 ,制备的ZnO薄膜处于压应变状态,而750℃时沉积的薄膜表现为张应变状态.沉积温度的不 同导致ZnO薄膜的折射率、消光系数、光学禁带宽度以及光致荧光特性的变化,沉积温度对 紫外光致荧光特性起着决定性的作用.此外,探讨了影响薄膜近紫外光致荧光发射的可能因 素.
关键词:
ZnO薄膜
表面形貌
微观结构
光学常数 相似文献
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采用溶胶-凝胶旋涂法在Si(111)衬底上生长了ZnO薄膜,并用荧光光谱、原子力显微镜和XRD对ZnO薄膜样品进行了分析.结果表明,溶胶-凝胶旋涂法制备的ZnO薄膜为纤锌矿结构,其c轴取向程度与热处理温度有很大的关系.当热处理温度小于550℃时,氧化锌薄膜在室温下均有较强的紫外带边发射峰,而可见波段的发射很弱;当热处理温度高于550℃时,可见波段发射明显增强.对经过不同时间热处理的ZnO薄膜样品分析表明,氧化锌薄膜的荧光特性及表面形貌与热处理时间也有很大关系,时间过短可见波段的发射较强,但时间过长会导致晶
关键词:
ZnO薄膜
光致发光 相似文献
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本文研究了脉冲激光沉积(PLD)生长过程中, 铝掺量、氧压及衬底温度等实验参数对ZnO:Al(AZO)薄膜生长的影响, 并利用扫描电子显微镜、原子力显微镜、X射线衍射、霍尔效应、光透射光谱等实验手段对其透明导电性能进行了探讨. 变温霍尔效应和光透射测量表明, 当靶材中铝掺量大于0.5 wt%时, 所制备AZO薄膜中铝施主在80 K时已完全电离, 因Bernstein-Moss (BM) 效应其带隙变大, 均为重掺杂简并半导体. 进一步系统研究了氧压和衬底温度对AZO薄膜透明导电性能的影响, 实验发现当氧压为1 Pa, 衬底温度为200 ℃时, AZO 导电性能最好, 其霍尔迁移率为28.8 cm2/V·s, 薄膜电阻率最小可达2.7×10-4 Ω·cm, 且在可见光范围内光透过率超过了85%. 氧压和温度的增加, 都会导致薄膜电阻率变大.
关键词:
脉冲激光沉积法
ZnO:Al薄膜
透光性
导电性 相似文献
9.
采用脉冲激光沉积(PLD)方法在Si(100)衬底上制备了NaF薄膜。在激光重复频率2 Hz,能量密度3 J/cm2,本底真空度5×10-5 Pa的条件下,研究衬底温度对薄膜沉积速率及结构的影响。台阶仪分析表明:薄膜的沉积速率随衬底温度增加呈指数函数增加,算出NaF薄膜的反应激活能为48.67 kJ/mol。原子力显微镜分析表明:薄膜致密而光滑,均方根粗糙度为0.553 nm。扫描电镜截面微观形貌分析表明:薄膜呈现柱状结构。X射线衍射分析表明:NaF薄膜为面心立方晶体结构,并具有显著的择优取向;当衬底温度约为400 ℃时,平均晶粒尺寸最大(129.6 nm),晶格微应变最小(0.225%)。 相似文献
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The easy direction of magnetization of the intermetallic compound ThFe5 has been determined by means of the Mössbauer effect and X-ray diffraction. From a resemblance between the results of these techniques, magnetization, neutron depolarization and magnetic neutron diffraction it can be concluded that ThFe5 has a complex ferrimagnetic moment arrangement with its easy axis of magnetization in the basal plane. 相似文献
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激光红外主被动复合导引系统 总被引:3,自引:0,他引:3
提出了采用激光主动三维成像技术配合被动红外成像技术共同工作的复合导引体制,用于提升地对地导弹的作战效能及对于隐身目标的识别能力。给出了各分系统的设计方案,并提出了合理的导引策略。该套系统能够兼顾红外大视场搜索及激光小视场三维成像,丰富的目标图像信息更加有利于对作战目标进行准确识别。整套复合光学导引系统结构简单、加工难度适中,在将整套导引系统口径控制在100 mm左右的情况下,同样能够实现4 km以上距离的导引。该项技术的提出对于我国复合导引技术的发展及我军导弹作战能力的提升有着重要意义。 相似文献
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Gordon R. Leader 《应用光谱学评论》2013,48(2):287-317
In recent years a number of papers have been published dealing with a new NMR technique which is useful for characterization of organic compounds which contain active hydrogen functional groups such as —OH, —NH2, and -SH [1–6]. This method, which involves use of hexafluoroacetone (HFA) and 19F NMR, is very easy to use since no preliminary preparation of a derivative of the compound being studied is necessary. It has been found to be generally superior in convenience, range of applicability, and ability to distinguish between closely related compounds to other techniques for the study of reactive functional groups which have previously been reported [8–11]. The simple addition of a small amount (typically 1 to 5 mg) of the compound being studied to a solution of HFA in ethyl acetate at ambient temperature results in the in situ formation of a stable adduct according to the general equation 相似文献
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研究应用拉曼光谱法分析验证氯霉素包合物的可行性。采用拉曼光谱仪和傅里叶红外光谱仪分别测得β-环糊精、氯霉素、β-环糊精和氯霉素物理混合物、氯霉素包合物四种物质固体粉末的拉曼图谱和红外图谱, 并对其进行对照分析。 结果表明拉曼光谱法可获得与红外光谱法一致的结果, 结果表明氯霉素的苯环结构和易水解基团二氯乙酰胺基通过氢键作用被包裹在β-环糊精的空穴结构中形成包合物, 增加了氯霉素的稳定性和溶出度, 并且拉曼光谱法具有快速、准确、简便、无损测量等显著优势, 可作为验证药物包合物的形成重要手段。 相似文献
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S. Sidi Ahmed G. Dimitri Ngantso M. Boujnah A. Benyoussef A. El Kenz 《Physics letters. A》2019,383(2-3):121-126
By using the density functional theory (DFT) and Monte Carlo simulations (MCS) with the Heisenberg model, we have studied magnetic properties of the bulk perovskite YCrO3. The exchange couplings of the Heisenberg model and the magnetic anisotropy are investigated. The 110 direction in the crystalline structure of the compound has shown the minimum energy, it is the easy magnetic direction. Using Monte Carlo simulations, the magnetizations behavior, the effects of system parameters and the critical exponents of the compound YCrO3 are implemented. It is shown that the bulk perovskite YCrO3 belongs to the 3D Heisenberg universality class. 相似文献
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《Journal of magnetism and magnetic materials》1987,67(2):190-192
The magnetostriction of a single crystal cubic Laves phase compound Tb0.27Dy0.73Fe2 is measured with the applied field (0–25 kOe) in the [111] direction in the temperature range between 80 and 300 K. Evidence is seen of a possible transition to the[uv0] easy axis phase during the spin re-orientation form [100] easy axis direction to the [110] easy axis direction. 相似文献
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A systematic investigation of nitrides R3Fe29-xCrxN4(R=Y, Ce, Nd, Sm, Gd, Tb, and Dy) has been performed. The nitrogen concentration in the nitride R3Fe29-xCrxNy was determined to be y=4. Nitrogenation leads to a relative volume expansion of about 5.3%. The lattice constants and unit cell volume decrease with in creasing rare earth atomic number from Nd to Dy, reflecting the lanthanide contraction. In average, the increase of Curie temperature upon nitrogenation is about 200 K, compared with its parent compound. The nitrogenation also results in a remarkable improvement in the saturation magnetization and anisotropy fields for R3Fe29-xCrxN4 at 4.2 K and room temperature, comp ared with their parent compounds. A spin reorientation of Nd3Fe24.5 Cr4.5N4 occurs at around 368 K, which is 138 K higher than that of Nd3Fe24.5Cr4.5.Magnetohistory effects of R3Fe29-xCrxN4(R=Nd and Sm) are observed in a low field of 0.04 T. First order magneti zation process occurs in Sm3Fe24.0Cr5.0N4 in magnetic fields of around 3.0 T at 4.2 K. After nitrogenation the easy magnetization direction of Sm3Fe24.0Cr5.0 is changed from the easy cone structure to the uniaxial. The excellent intrinsic magnetic properties of Sm3Fe24.0Cr5.0N4 make this compound a hopeful candidate for new high performance permanent magnets. 相似文献
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Andrew S. Bell Joseph Bradley Jeremy R. Everett Jens Loesel David McLoughlin James Mills Marie-Claire Peakman Robert E. Sharp Christine Williams Hongyao Zhu 《Molecular diversity》2016,20(4):789-803
High-throughput screening (HTS) is an effective method for lead and probe discovery that is widely used in industry and academia to identify novel chemical matter and to initiate the drug discovery process. However, HTS can be time consuming and costly and the use of subsets as an efficient alternative to screening entire compound collections has been investigated. Subsets may be selected on the basis of chemical diversity, molecular properties, biological activity diversity or biological target focus. Previously, we described a novel form of subset screening: plate-based diversity subset (PBDS) screening, in which the screening subset is constructed by plate selection (rather than individual compound cherry-picking), using algorithms that select for compound quality and chemical diversity on a plate basis. In this paper, we describe a second-generation approach to the construction of an updated subset: PBDS2, using both plate and individual compound selection, that has an improved coverage of the chemical space of the screening file, whilst only selecting the same number of plates for screening. We describe the validation of PBDS2 and its successful use in hit and lead discovery. PBDS2 screening became the default mode of singleton (one compound per well) HTS for lead discovery in Pfizer. 相似文献
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The structural and magnetic anomaly of the layered compound SrFeO2 are examined by first-principles density functional calculations and Monte Carlo simulations. The down-spin Fe 3d electron occupies the d(z(2)) level rather than the degenerate (d(xz), d(yz)) levels, which explains the absence of a Jahn-Teller instability, the easy ab-plane magnetic anisotropy, and the observed three-dimensional (0.5, 0.5, 0.5) antiferromagnetic order. Monte Carlo simulations show that the strong interlayer spin exchange is essential for the high Néel temperature. 相似文献