Multi-Dimensional Dopant Profiling With Atomic Resolution by Scanning Tunneling Microscopy
Liu, Lequn
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https://hdl.handle.net/2142/82721
Description
Title
Multi-Dimensional Dopant Profiling With Atomic Resolution by Scanning Tunneling Microscopy
Author(s)
Liu, Lequn
Issue Date
2002
Doctoral Committee Chair(s)
Lyding, Joseph W.
Department of Study
Materials Science and Engineering
Discipline
Materials Science and Engineering
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Engineering, Electronics and Electrical
Language
eng
Abstract
The lack of surface states within the band gap of the perfect Si(100)2x1:H surface opens the way to STM studies of dopant distributions in Si(100). STM topographic images, dI/dV images and current image tunneling spectroscopy (CITS) were acquired across the lateral PN junctions of Si devices. Two-dimensional dopant (carrier) profiles were extracted from CITS data with 5A resolution. Moreover, the N and P type dopant induced features were observed in filled state and empty state STM images. The donor (Arsenic) induced feature appears as a protrusion in both the filled and empty state images, while the acceptor (Boron) induced feature appears as a hillock in the filled state image and a depression in the empty state image. The bias dependence, depth dependence and dopant concentration dependence of the dopant induced features were investigated in detail. Based on scattering theory, the numerical calculation was performed to achieve a fundamental understanding of dopant induced features, and the calculation results were in qualitative agreement with the experimental observations. The potential application of this study for 3D dopant profiling with atomic resolution on both P and N type samples is discussed, and the optimal scanning conditions are also suggested. This work reveals the real physical picture of randomly distributed dopants and may be useful to verify and calibrate TCAD simulators.
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