Ballistic Electron Emission Microscopy

Author : Eric Heller
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (555 download)

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Download or read book Ultra Low Signals in Ballistic Electron Emission Microscopy written by Eric Heller and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: In this work it is first shown that internal gain can be applied specifically to hot BEEM electrons without amplifying standard BEEM noise sources. It is shown that BEEM with single hot electron sensitivity (approximately a factor of 1000 improvement in the minimum detectable BEEM signal) is attainable with modified commercially existing avalanche photodiodes. This allows useful data collection at lower signal levels than previously possible. With this new low-signal capability, it was obvious that a new BEEM-like signal was being detected. We have discovered that STM tunneling generated photons that will create a false signal in most BEEM samples. Furthermore, we have characterized this effect which we call "STM-PC" and it is demonstrated with Pd/SiO2/Si and Au/SiO2/Si samples that this false signal closely mimics BEEM and is easily confused for BEEM. We discuss ways to separate real BEEM from this new effect. Separately, thermally generated kinks on steps on the Si(001) surface are counted and analyzed to determine the energy of the SB-type step. Previous work by others is extended by counting a new type of feature, the "switch" kink, to allow a more accurate determination of the energy of SB-steps in the presence of defects that will bow steps and cause non-thermal kinks. Extensive data collection along with this new extension allows a more accurate determination of the B-type kink energy than before and the first experimental evidence that this energy increases with tensile strain on the Si(001) surface. Modifications to an Omicron Variable Temperature Scanning Tunneling Microscope (VT-STM) will be presented. The VT-STM will be moved to the Electrical Engineering Department cleanroom of The Ohio State University and will allow in-situ studies of Molecular Beam Epitaxy (MBE) grown samples. Modifications, repairs, and operating procedures will be discussed for the VT-STM and supporting hardware. The bulk of the modifications to be discussed have been to allow sample transfer between the STM and the MBE machine. Last, work on Low Temperature Grown Gallium Arsenide (LTG-GaAs) will be presented. The ultimate goal of detecting nm-scale arsenic precipitates that form with annealing using BEEM was not successful.