Centre for Nanotechnology, Department of Electrical and Computer Engineering, University of Toronto, 170 College Street, Toronto, Ontario M5S 3E4, Canada.
ACS Nano. 2011 Mar 22;5(3):2191-9. doi: 10.1021/nn1033967. Epub 2011 Feb 15.
We report a novel method for probing the gate-voltage dependence of the surface potential of individual semiconductor nanowires. The statistics of electronic occupation of a single defect on the surface of the nanowire, determined from a random telegraph signal, is used as a measure for the local potential. The method is demonstrated for the case of one or two switching defects in indium arsenide (InAs) nanowire field effect transistors at temperatures T=25-77 K. Comparison with a self-consistent model shows that surface potential variation is retarded in the conducting regime due to screening by surface states with density Dss≈10(12) cm(-2) eV(-1). Temperature-dependent dynamics of electron capture and emission producing the random telegraph signals are also analyzed, and multiphonon emission is identified as the process responsible for capture and emission of electrons from the surface traps. Two defects studied in detail had capture activation energies of EB≈50 meV and EB≈110 meV and cross sections of σ∞≈3×10(-19) cm2 and σ∞≈2×10(-17) cm2, respectively. A lattice relaxation energy of Sℏω=187±15 meV was found for the first defect.
我们报告了一种探测半导体纳米线表面电势随栅极电压变化的新方法。通过随机电报信号确定的单个纳米线表面缺陷的电子占据统计量被用作局部电势的测量。该方法在 25-77 K 温度下的砷化铟（InAs）纳米线场效应晶体管中一个或两个开关缺陷的情况下进行了演示。与自洽模型的比较表明，由于表面态的屏蔽，在导电状态下表面电势的变化被延迟，表面态密度 Dss≈10(12) cm(-2) eV(-1)。还分析了产生随机电报信号的电子俘获和发射的温度相关动力学，并且确定多声子发射是导致表面陷阱中电子俘获和发射的过程。详细研究的两个缺陷的俘获激活能分别为 EB≈50 meV 和 EB≈110 meV，截面分别为 σ∞≈3×10(-19) cm2 和 σ∞≈2×10(-17) cm2。第一个缺陷的晶格弛豫能量 Sℏω=187±15 meV。
