In situ ellipsometric study of the formation process of metalorganic vapor-phase epitaxy-grown quantum dots

Our in situ ellipsometry study of metalorganic vapor-phase epitaxy-grown qu antum dot (QD) structures showed that the Delta-Psi trajectory of the ellip sometric signal in Stranski-Krastanow QD growth sharply differs from that i n layer-by-layer growth. When QD formation starts, a rapidly decreases, inf lecting the Delta-Psi trajectory. This indicates increased scattering loss, deduced from increased surface roughness produced in the transition from t wo- to three-dimensional surface morphology. Ex situ atomic force microscop y and photoluminescence results correspond well to the ellipsometric signal at the start of QD formation. Based on these results, we discuss growth-de pendent QD formation processes such as QD formation onset and growth mode t ransition. (C) 1999 American Vacuum Society. [S0734-211X(99)02304-5].