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Scanning transmission electron microscopy measurement of bismuth segregation in thin Ga(As,Bi) layers grown by molecular beam epitaxy
Author(s) -
Walther Thomas,
Richards Robert D.,
Bastiman Faebian
Publication year - 2015
Publication title -
crystal research and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.377
H-Index - 64
eISSN - 1521-4079
pISSN - 0232-1300
DOI - 10.1002/crat.201400157
Subject(s) - molecular beam epitaxy , bismuth , scanning transmission electron microscopy , materials science , transmission electron microscopy , dark field microscopy , scanning electron microscope , epitaxy , thin film , analytical chemistry (journal) , crystallography , optics , microscopy , chemistry , nanotechnology , layer (electronics) , composite material , physics , chromatography , metallurgy
Annular dark‐field (ADF) imaging in a scanning transmission electron microscope (STEM) has been used to measure concentration profiles across thin Ga(As,Bi) layers grown by molecular beam epitaxy, from which the segregation lengths for bismuth surface segregation have been calculated. Performing this for layers grown at two different temperatures, the activation energies for Bi surface segregation have been determined for the lower (GaAsBi‐on‐GaAs) and for the upper (GaAs‐on‐GaAsBi) interface. The inequivalence observed is attributed to strain driving the larger Bi atoms preferably towards the free surface during growth.