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Vol.44, No.7, 518 ~ 527, 2006
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| Title |
| Structure and Strain Characteristics of Self-Assembled InAs/GaAs Quantum Dots Investigated by Transmission Electron Microscopy |
| 김형석 Hyung Seok Kim , 서주형 Ju Hyung Suh , 박찬경 Chan Gyung Park , 이상준 Sang Jun Lee , 노삼규 Sam Kyu Noh , 송진동 Jin Dong Song , 박용주 Yong Ju Park , 최원준 Won Jun Choi , 이정일 Jung Il Lee |
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| Abstract |
| Self-assembled InAs/GaAs quantum dots (QDs) were grown by molecular-beam epitaxy and their structure and strain characteristics were studied by using transmission electron microscopy (TEM). TEM investigations were performed by conventional bright field TEM, high-resolution electron microscopy (HREM), annular dark field (ADF) and high angle annular dark filed (HAADF)-STEM techniques. In addition, strain analysis was performed on an atomic-length scale by measuring the space of lattices in HREM. The QDs were found to form a lens-shaped structure with side facet. Compressive strain was induced to uncapped QDs from GaAs substrate and the strain increased more than 3.5% after GaAs cap layer growth. On the other hand, tensile strain by capped QDs was induced to GaAs up tolO nm over the QDs, i.e. 15 nm over the wetting layer. It was also confirmed that the tensile strain extension resulted in aligned QD growth with 15 nm thick spacers. Vertically aligned QDs could be grown by the tensile strain from predeposited QDs when the thickness of GaAs spacer was less than 15 nm. |
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| Key Words |
| InAs/GaAs Quantum Dot, Microstructure of Quantum Dot, Misfit Strain, Multilayer-Stacked Quantum Dots, Transmission Electron Microscopy |
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