title: Nonuniform composition profile in In0.5Ga0.5As alloy quantum dots
abstract: We use cross-sectional scanning tunneling microscopy to examine the shape and composition distribution of In0.5Ga0.5As quantum dots (QDs) formed by capping heteroepitaxial islands. The QDs have a truncated pyramid shape. The composition appears highly nonuniform, with an In-rich core having an inverted-triangle shape. Thus the electronic properties will be drastically altered, relative to the uniform composition generally assumed in device modeling. Theoretical analysis of the QD growth suggests a simple explanation for the unexpected shape of the In-rich core.
authors.affiliation: Department of Physics, The University of Texas, Austin, Texas 78712, USA.
authors.initials: N
authors.lastname: Liu
authors.initials: J
authors.lastname: Tersoff
authors.initials: O
authors.lastname: Baklenov
authors.initials: AL
authors.lastname: Holmes
authors.initials: CK
authors.lastname: Shih