AVS 51st International Symposium
    Surface Science Thursday Sessions
       Session SS+EM+SC-ThA

Paper SS+EM+SC-ThA3
Quantitative Analysis of Indium Concentration in InGaAs Quantum Dots and Wetting Layers Using Cross-sectional Scanning Tunneling Microscopy

Thursday, November 18, 2004, 2:40 pm, Room 210C

Session: Compound Semiconductor Growth and Surface Structure
Presenter: C.-K. Shih, University of Texas at Austin
Authors: N. Liu, University of Texas at Austin
S. Govindaraju, University of Texas at Austin
A.L. Holmes Jr., University of Texas at Austin
C.-K. Shih, University of Texas at Austin
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Scanning tunneling microscopy has been employed to explore self-assembled InGaAs quantum dots (QDs) grown by migration enhanced epitaxy (MEE). With atomic resolution, compositional analysis has been done for both the QDs and wetting layers quantitatively. We found that both vertical and lateral segregation play important roles during the formation of the islands and thereafter capping procedure. Depletion of the wetting layer, due to the formation of the QDs, is demonstrated. More importantly, it is found that after capping the amount of existing indium in the QDs and WL is less than that of deposited indium, indicating a portion of deposited indium atoms was evaporated to the vacuum during overgrowth of GaAs. This observation is different from previous results, which proposed indium re-distribution within GaAs matrix after capping growth. Based on the observed data, a growth model is also proposed.