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Title:Generation and relaxation of nanometer-scale roughness on the germanium(001) surface
Author(s):Chey, S. Jay
Doctoral Committee Chair(s):Cahill, David G.
Department / Program:Physics, Condensed Matter
Engineering, Materials Science
Discipline:Physics, Condensed Matter
Engineering, Materials Science
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Physics, Condensed Matter
Engineering, Materials Science
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
Issue Date:1996
Rights Information:Copyright 1996 Chey, S. Jay
Date Available in IDEALS:2011-05-07
Identifier in Online Catalog:AAI9712229
OCLC Identifier:(UMI)AAI9712229

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