Nonuniform composition profile in In0.5Ga0.5As alloy quantum dots
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.
Liu
N
Department of Physics, The University of Texas, Austin, Texas 78712, USA.
Tersoff
J
Baklenov
O
Holmes
AL
Shih
CK