共查询到17条相似文献,搜索用时 46 毫秒
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本文以低维化合物系统为主研究对象,介绍利用扫描探针显微镜进行隧道谱测量的基本原理及一些实验成果。 相似文献
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开展了HgCdTe 晶体的多脉冲热损伤问题的实验研究。采用形貌学方法对脉宽为300 ns 重复频率可调的CO2 激光器对Hg0.826Cd0.174Te 晶体的损伤阈值进行了实验测量,并建立了高重频脉冲CO2 激光辐照Hg0.826Cd0.174Te 晶体的三维热传导理论模型,分析了激光重复频率和辐照时间对晶体损伤特性的影响。研究表明:300 ns 的CO2 激光辐照时间大于10 s时,Hg0.826Cd0.174Te 晶体的损伤阈值不随辐照时间的增加而改变,其损伤阈值为1.421 4103W/cm2;激光重频对晶体的损伤阈值的影响较小,损伤阈值主要取决于辐照激光的平均功率密度。SEM 损伤结果显示:晶体损伤为热熔损伤,表面未发现由热应力造成的裂缝。理论模型获得的损伤数据和温升规律支持实验结果。该研究可为高重频CO2 激光应用、激光防护等提供参考。 相似文献
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利用超高真空扫描隧道显微镜的隧道谱实验对汞空位掺杂的液相外延P型碲镉汞材料在室温条件下进行测量,发现直接的电流-电压隧道谱对带隙预言一定程度上要受到成像偏置电压的影响.但当采用了锁相放大测量技术,通过实验直接获取微分隧道谱(dI/dV)信号,并利用电流-电压谱对dI/dV作归一化处理时,最终结果则能较准确、可靠地预言材料的带隙,表明扫描隧道谱方法作为独立于光学方法之外的另一种实验表征手段对碲镉汞能带电子结构研究的适用性. 相似文献
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扫描隧道显微镜是一种分辨率极高的表面研究仪器,针尖对其工作过程及图像质量有决定性的影响。本文针对目前针尖腐蚀成功率较低和不稳定的缺点,提出了一种新的电路。该设计改变了反应电流的测量机制,使实际反应电压在实验过程中保持稳定,同时为了得到更加尖锐的针尖,利用差分电路监控反应过程的电流变化,能够在反应结束的瞬间立刻切断电路,避免了过度反应使针尖变钝。最后,通过观察反应电压,阴极圆环位置,差分电路灵敏度以及电解液浓度对针尖质量的影响,给出了合适的反应参数,并且比较了差分电路和传统电流阈值监控法的优缺点。结果表明新电路在稳定性上有所提高,与电流阈值监控法相比,针尖质量更好,另外扫描隧道显微镜测试结果也表明针尖质量完全符合要求。 相似文献
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利用超高真空扫描隧道显微镜对经过溴甲醇溶液腐蚀处理的液相外延碲镉汞材料进行了表征.发现经过腐蚀处理(3%浓度,2.5 min)的样品表面出现高密度的凹坑结构,凹坑深度约几十纳米,横向尺度在几十到几百纳米之间.扫描隧道谱测量表明,腐蚀样品表面平坦区呈现较大表观带隙,需考虑针尖诱导的能带弯曲效应,而凹坑区在零偏压区的扫描隧道谱线则近似为线性变化,说明该区域包含较高的带隙态并直接参与隧穿,从而掩盖了带隙信息. 相似文献
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扫描隧道显微镜钨针尖氧化层去除的化学方法 总被引:2,自引:0,他引:2
电化学腐蚀得到的扫描隧道显微镜(STM)钨针尖表面通常覆盖了一层钨的氧化膜,这层氧化膜的存在很大程度上影响了STM扫描图像质量.本实验采用氢氟酸对新制备出的钨针尖进行去氧化层处理,并通过对比两组高序热解石墨(HOPG)STM图像和金样品的扫描隧道谱来论证这种去氧化层手段的有效性. 相似文献
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本文探讨了扫描隧道显微镜中的样品成分分析问题,提出了分析元素的方案,认为二极式结构的俄歇电子出现势谱具有很好的前景,本文对二极式结构的俄歇电子出现势谱的实验作了介绍,并提出了提高其性能的一些方法使它具有应用的可能。 相似文献
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Linghao Yan Orlando J. Silveira Benjamin Alldritt Ondřej Krejčí Adam S. Foster Peter Liljeroth 《Advanced functional materials》2021,31(22):2100519
Achieving large-area uniform 2D metal-organic frameworks (MOFs) and controlling their electronic properties on inert surfaces is a big step toward future applications in electronic devices. Here a 2D monolayer Cu-dicyanoanthracene MOF with long-range order is successfully fabricated on an epitaxial graphene surface. Its structural and electronic properties are studied by low-temperature scanning tunneling microscopy and spectroscopy complemented by density-functional theory calculations. Access to multiple molecular charge states in the 2D MOF is demonstrated using tip-induced local electric fields. It is expected that a similar strategy could be applied to fabricate and characterize 2D MOFs with exotic, engineered electronic states. 相似文献
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Wonhee Ko Chuanxu Ma Giang D. Nguyen Marek Kolmer An‐Ping Li 《Advanced functional materials》2019,29(52)
Scanning tunneling microscope (STM) has presented a revolutionary methodology to nanoscience and nanotechnology. It enables imaging of the topography of surfaces, mapping the distribution of electronic density of states, and manipulating individual atoms and molecules, all at atomic resolutions. In particular, atom manipulation capability has evolved from fabricating individual nanostructures toward the scalable production of the atomic‐sized devices bottom‐up. The combination of precision synthesis and in situ characterization has enabled direct visualization of many quantum phenomena and fast proof‐of‐principle testing of quantum device functions with immediate feedback to guide improved synthesis. Several representative examples are reviewed to demonstrate the recent development of atomic‐scale manipulation, focusing on progress that addresses quantum properties by design in several technologically relevant materials systems. Integration of several atomically precisely controlled probes in a multiprobe STM system vastly extends the capability of in situ characterization to a new dimension where the charge and spin transport behaviors can be examined from mesoscopic to atomic length scale. The automation of atomic‐scale manipulation and the integration with well‐established lithographic processes further push this bottom‐up approach to a new level that combines reproducible fabrication, extraordinary programmability, and the ability to produce large‐scale arrays of quantum structures. 相似文献
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Gianlorenzo Bussetti Marcello Campione Michele Riva Andrea Picone Luisa Raimondo Lorenzo Ferraro Conor Hogan Maurizia Palummo Alberto Brambilla Marco Finazzi Lamberto Duò Adele Sassella Franco Ciccacci 《Advanced functional materials》2014,24(7):958-963
A major challenge in molecular electronics is to develop logic devices based on a truly intramolecular switching mechanism. Recently, a new type of molecular device has been proposed where the switching characteristic is mediated by the bistability in the position of the two hydrogen atoms which can occupy different, energetically equivalent positions (tautomerization) in the inner cavity of porphyrins and naphthalocyanines. Up to now, such a reaction has only been exploited at low temperatures and induced or detected through atomic scale manipulation. In addition, the unpredictability of the tautomer orientation currently excludes molecular interconnection to functional electronic circuits. Here, full evidence is provided that, following a newly proposed growth strategy, 2D layers of metal‐free tetraphenylporphyrins (H2TPP) show frozen tautomerization even at room temperature on macroscopic domains, with the H atoms aligned along a direction settled a priori. This behavior is ascribed to the buckling of the molecule, anchored to the substrate, which removes the degeneracy between the two tautomer alignments. On this basis, a new way to exploit uniaxially oriented H2TPP tautomers in a first elementary logic device is proposed. 相似文献
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Organic Electronics: Stable Alignment of Tautomers at Room Temperature in Porphyrin 2D Layers (Adv. Funct. Mater. 7/2014)
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Gianlorenzo Bussetti Marcello Campione Michele Riva Andrea Picone Luisa Raimondo Lorenzo Ferraro Conor Hogan Maurizia Palummo Alberto Brambilla Marco Finazzi Lamberto Duò Adele Sassella Franco Ciccacci 《Advanced functional materials》2014,24(7):957-957
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Jeremy Hieulle Dae-Yong Son Afshan Jamshaid Xin Meng Collin Stecker Robin Ohmann Zonghao Liu Luis K. Ono Yabing Qi 《Advanced functional materials》2023,33(9):2211097
Mixing cations in the perovskite structure has been shown to improve optoelectronic device performance and stability. In particular, CsxMA1-xPbBr3 (MA = CH3NH3) has been used to build high-efficiency light-emitting diodes. Despite those advantages, little is known about the exact location of the cations in the mixed perovskite film, and how cation distribution affects device properties and stability. By using scanning tunneling microscopy , the exact atomic structure of the mixed cation CsxMA1-xPbBr3 perovskite interface is revealed. In addition, X-ray photoelectron spectroscopy, ultraviolet photoemission spectroscopy and inverse photoemission spectroscopy are used to study the stability and electronic properties of the CsxMA1-xPbBr3 perovskite film. Partial substitution of MA+ by Cs+ induces a modification of the perovskite surface structure, leading to improved device stability is shown. These results provide a better understanding of the key parameters involved in the stability of mixed cation perovskite solar cells. 相似文献
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Caixia Ren Jiangbo Peng Hu Chen Weili Zhang Xiaoguang Pan Hangxin Bai Yongzheng Wang Fangli Jing Hailong Qiu Yukai An Zhanggui Hu Hongjun Liu 《Advanced functional materials》2023,33(32):2301533
Substitutional lanthanide doping of 2D transition metal dichalcogenides (TMDs) is expected to be a promising strategy to engineer optical, electronic, and optoelectronic properties of TMDs. Understanding the interactions between lanthanide dopants and 2D TMDs host is one of the key problems to be resolved for their profound research studies. Herein, the interactions between Ce dopants and monolayer WS2 in a physical vapor deposition grown Ce-doped WS2 monolayer are studied by combining scanning tunneling microscopy with optical characterizations with high spatial and temporal resolution. It is found that the highly anisotropic crystal field can effectively split the energy levels of the Ce dopants’ f orbital. The electrons in the split energy levels can bind the holes in the valence band maximum of the Ce-doped WS2, forming optical bright excitons. These excitons collide with the free A excitons when increasing the pump fluences, reducing the A exciton's lifetime. This study may be beneficial for the design and fabrication of optical, electronic, and optoelectronic devices based on lanthanide-doped TMDs. 相似文献
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