We present a quantitative technique for the direct compositional analysis o
f quantum dots (QDs), in which scanning transmission electron microscopy is
applied to a capped InAs/GaAs QD layer in a structure also containing InxG
a1-xAs/GaAs quantum well (QW) layers to provide an internal calibration of
the In content. By obtaining energy dispersive x-ray analysis line scans th
rough both QWs and QDs, the composition of the QDs can be determined by ref
erence to the known composition of the QWs. In this article the method is d
escribed and demonstrated using two InAs/GaAs structures in which the QDs a
re nominally identical, but with different In composition in the calibratio
n QW layers. We find that the QDs in both structures have an In composition
of 65%-67% and the associated wetting layers contain approximately 12% In.
(C) 2001 American Institute of Physics.