The formation of quantum dot structures in 30-pair InGaN/GaN multiple quantum wells after proper thermal annealing treatment
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This study systematically investigates the relation between strain energy and quantum dot (QD) formation for 30- pair InGaN/GaN multiple quantum wells (QW) by means of atomic force microscopy and high-resolution transmission electron microscopy. The results show that a higher number of quantum wells induce a higher strain energy and higher density of V-shaped defects, which increases the number of non-radiative centers. However, after thermal annealing, the strain energy accumulated from stacking faults is released and leads to the formation of a QDs structure. The strain energy around the quantum dot structure was calculated using by the NCEM Phase Extensions to the Digital Micrograph. The zone of higher strain energy was observed, which proves that the strain energy is the driving force for the formation of quantum dot structures.
KeywordsQuantum Well Misfit Dislocation Carrier Localization Thermal Annealing Process High Strain Energy
This research was supported by the National Science Council, Republic of China, under grants NSC 96-2623-7-214-002-NU and NSC96-2221-E-214-019-MY2.
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