Generation and relaxation of nanometer-scale roughness on the germanium(001) surface
Chey, S. Jay
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https://hdl.handle.net/2142/23697
Description
Title
Generation and relaxation of nanometer-scale roughness on the germanium(001) surface
Author(s)
Chey, S. Jay
Issue Date
1996
Doctoral Committee Chair(s)
Cahill, David G.
Department of Study
Physics, Condensed Matter
Engineering, Materials Science
Discipline
Physics, Condensed Matter
Engineering, Materials Science
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Physics, Condensed Matter
Engineering, Materials Science
Language
eng
Abstract
The surface morphology of Ge(001) during etching by low energy ions is characterized using scanning tunneling microscopy. The surfaces are bombarded by 240 eV xenon ions at various temperatures and exposure times. A well defined in-plane length scale is observed on the crystalline surfaces etched at $165270\sp\circ$C exhibit a regular pattern of pits. The isotropy of this pattern formation of pits argues against surface curvature dependent sputtering rate and suggests that asymmetric kinetics for the attachment of dimer vacancies at ascending and descending steps drive roughening during etching.
The surface defects created on Ge(001) exposed to low energy ions are characterized by scanning tunneling microscopy. The temperature during ion bombardment is 165$\sp\circ$C and ion energies range from 20 to 240 eV. The ion collisions create defects (vacancies and adatoms) which nucleate and form vacancy and adatom islands. The vacancy island density increases with increasing ion energy. The increased rate for vacancies is attributed to clustering of defects. The sputtering yield for 20 eV ion is approximately 10$\sp{-3}$ but the net yield for surface defects (sum of adatoms and vacancies) is an order of magnitude higher, $\sim$10$\sp{-2}$, due to adatom-vacancy pair creation.
Relaxation of a nanometer length scale roughness of Ge(001) is studied by scanning tunneling microscopy. Rough surfaces with in-plane length scale L of $37\sim 118$ nm are created by ion etching and annealed at $245
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