NSTI Nanotech 2009

Real time RHEED characterization of Quantum dots

C. Rajapaksha, A. Freundlich
University of Houston, US

Keywords: reflection high energy electron diffraction, quantum dot

Abstract:

We provide an in situ approach to the determination of quantum dots size and shape based on calculated reflection high energy electron diffraction (RHEED) patterns. We observe the periodic intensity fringes along the RHEED chevron tails predicted earlier by the theoretical model. The calculated and observed RHEED intensity profiles are analyzed systematically for different QD heights. The periodicity of the intensity fringes is correlated to the average height of the quantum dots. We observe facet reflections along the [1-30] and [3-10] azimuths with chevrons with an included angle of 56 degrees, which indicate that the quantum dot shape is pyramidal with bounding facets corresponding to a family of (137) planes according to our calculations.The possibility of monitoring real time the evolution of dot height and shape during the MBE/CBE growth of self assembled quantum dots is demonstrated.
 
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