Role of atomic force in tunneling‐barrier measurements
作者:
C. J. Chen,
R. J. Hamers,
期刊:
Journal of Vacuum Science&Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena
(AIP Available online 1991)
卷期:
Volume 9,
issue 2
页码: 503-505
ISSN:1071-1023
年代: 1991
DOI:10.1116/1.585556
出版商: American Vacuum Society
关键词: SILICON;SURFACES;SCANNING TUNNELING MICROSCOPY;TUNNEL EFFECT;POTENTIAL BARRIER;ULTRAHIGH VACUUM;INTERATOMIC FORCES;MATHEMATICAL MODELS
数据来源: AIP
摘要:
Experimental measurements of the apparent barrier height as a function of tip‐sample separation using a scanning tunneling microscope (with cleanWtips and clean Si surfaces in ultra high‐vacuum) show that the barrier height starts at 3.5 eV at large separations, increases to 4.8 eV at about 1.5 Å before the mechanical contact, and then drops to below 0.3 eV within a fraction of an ångström. At the distances encountered in scanning tunneling microscopy, forces between sample and tip can be significant. Using a simple model of this system including tip‐sample forces leads to a calculated apparent barrier height which quantitatively reproduces the observed variation in apparent barrier height over the entire range of tip‐sample separations.
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