共查询到18条相似文献,搜索用时 93 毫秒
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目前对于纳米尺度半导体材料的局域电导与对应载流子浓度关系的描述主要以参数拟合为主。其关系模型主要依赖人工拟合参数, 例如理想因子。所以无法从测得局域电导分布来推出载流子浓度分布。为此, 提出了一种获取量子阱中载流子浓度的模型。通过小于10nm分辨的截面扫描分布电阻显微术, 测得了GaAs/AlGaAs量子阱 (110) 截面的局域电导分布。基于实验设置, 提出了只含有掺杂浓度参量的实验描述模型。通过模型, 由测得的量子阱 (掺杂浓度从1016/cm3到1018/cm3) 局域电导分布, 推导出了其载流子分布。相对误差在30%之内。 相似文献
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三维取向是单分子的一个重要特性,单分子三维取向研究是近年来对单分子研究的又一热点。综述了基于远场扫描的三种探测方法,阐述了其基本原理,分析、比较了各种方法的优缺点,讨论了进行单分子三维取向检测所存在的困难和实际问题,展望了其广阔的应用领域及前景。 相似文献
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结合扫描隧道显微镜(STM)成像实验和第一性原理原子级模拟计算的方法已经成为材料界面表征的重要手段。超高真空条件下的STM可用于直接观察单原子等微观结构,但其成像原理还未被理解清楚。STM扫描测得的试件表面原子级图像并不直接反映材料原子的形态,实际上是表面形貌和表面电子态局域密度的综合结果。为了解释STM成像,采用第一性原理Siesta方法,研究了Si(001)面STM成像过程的电子结构,对表面粒子的原子轨道和相应的电荷密度进行计算。讨论了等高模式下扫描高度对局域电子云密度分布的影响,并分析了STM针尖几何形状对模拟结果的影响。研究表明,材料表面原子的电子云密度分布可以用来解释STM成像精度和扫描高度对比的变化。 相似文献
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利用密度泛函理论与非平衡格林函数相结合的数值分析方法,以均匀型和十字型两种不同类型的石墨烯纳米带作为沟道,研究了石墨烯纳米带场效应管(GNRFET)的负微分电阻效应。分析了不同类型GNRFET的端口输运性质:均匀型GNRFET具有良好的输运特性;十字型GNRFET由于中间的干破坏了原来两边缘的输运路径,其传输系数均不超过1。十字型GNRFET的输出特性具有明显的负微分电阻效应,且栅电压对此有调控作用。从传输谱的角度给出了GNRFET负微分电阻特性的理论解释和栅压调控的能量图,为微纳器件负微分电阻效应的研究提供了一定的理论依据。 相似文献
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扫描探针显微镜(SPM)作为一种广泛应用的表面表征工具,不仅可以表征三维形貌,还能定量地研究表面的粗糙度、孔径大小和分布及颗粒尺寸,在许多学科均可发挥作用.以纳米材料为主要研究对象,综述了国外最新的几种扫描探针显微表征技术,包括扫描隧道显微镜(STM)、原子力显微镜(AFM)和近场扫描光学显微镜(SNOM)等方法,展示了这几种技术在纳米材料的结构和性能方面的应用. 相似文献
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M. A. Schneider M. Wenderoth A. J. Heinrich M. A. Rosentreter R. G. Ulbrich 《Journal of Electronic Materials》1997,26(4):383-386
Spatial variations of the local electric field in current-carrying thin gold films were studied with a scanning tunneling
microscope on a nanometer scale. With a refined scanning tunneling potentiometry technique, it was possible to determine the
local electric fields within single grains. At grain boundaries, we observe potential drops on length scales of less than
1 nm which exceed the potential difference within a grain greatly. We interpret our findings by applying a theory that models
grain boundaries as barriers with a reflectivity R for the conduction electrons. With the assumption of isotropic background
scattering within each grain, we determine the local current-density j(x,y) that passes a grain boundary. From that, we obtain
the reflectivity of individual grain boundaries and find values ofR = 0.7toR = 0.9 which is much higher than expected from
macroscopic experiments. 相似文献
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报道了由超薄基区负阻异质结双极晶体管(UTBNDRHBT)构成的非稳多谐振荡器,具有高速、可调控等优点。对其电压控制脉冲频率调制效应进行了实验研究,观察到了仅由基极电压(V_(BE))即可控制脉冲间距和脉冲宽度;对实验现象给出了相应分析,并指出了此电路的应用前景。 相似文献
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Khalid Quertite Hanna Enriquez Nicolas Trcera Yongfeng Tong Azzedine Bendounan Andrew J. Mayne Gérald Dujardin Pierre Lagarde Abdallah El kenz Abdelilah Benyoussef Yannick J. Dappe Abdelkader Kara Hamid Oughaddou 《Advanced functional materials》2021,31(7):2007013
Silicene, a new 2D material has attracted intense research because of the ubiquitous use of silicon in modern technology. However, producing free-standing silicene has proved to be a huge challenge. Until now, silicene could be synthesized only on metal surfaces where it naturally forms strong interactions with the metal substrate that modify its electronic properties. Here, the authors report the first experimental evidence of silicene nanoribbons on an insulating NaCl thin film. This work represents a major breakthrough, for the study of the intrinsic properties of silicene, and by extension to other 2D materials that have so far only been grown on metal surfaces. 相似文献
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C. D. Lee V. Ramachandran A. Sagar R. M. Feenstra D. W. Greve W. L. Sarney L. Salamanca-Riba D. C. Look Song Bai W. J. Choyke R. P. Devaty 《Journal of Electronic Materials》2001,30(3):162-169
The structural, electrical, and optical properties of GaN grown on 6H-SiC(0001) substrates by molecular beam epitaxy are studied.
Suitable substrate preparation and growth conditions are found to greatly improve the structural quality of the films. Threading
dislocation densities of about 3×109 cm−2 for edge dislocations and <1×106 cm−2 for screw dislocations are achieved in GaN films of 0.8 μm thickness. Mechanisms of dislocation generation and annihilation
are discussed. Increasing the Ga to N flux ratio used during growth is found to improve the surface morphology. An unintentional
electron concentration in the films of about 5×1017 cm−3 is observed, and is attributed to excess Si in the films due to a Si-cleaning step used in the substrate preparation. Results
from optical characterization are correlated with the structural and electronic studies. 相似文献
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采用直流电化学刻蚀方法制备扫描隧道显微镜钨针尖,研究了电化学刻蚀过程中NaOH溶液浓度、钨丝浸入长度和刻蚀电压对针尖形貌的影响。通过扫描电子显微镜(SEM)测量针尖曲率半径和针尖纵横比值,以表征针尖的尺寸和形状;通过能谱仪(EDS)分析针尖表面成分,以表征表面清洁度;通过场发射显微镜(FEM)得到Fowler-Nordheim (F-N)曲线来检测针尖发射性能。实验结果表明,当溶液浓度为2 mol/L、钨丝浸入长度为4 mm、刻蚀电压为3 V时,可以得到曲率半径约为100 nm、纵横比值为13的针尖,且表面无钨的氧化层。FEM结果显示当对针尖施加500 V的负偏压时,针尖可以稳定发射50 nA量级的电流,且针尖性能具有良好的一致性。 相似文献