Transmission Electron Microscopy Studies on InGaN/GaN Quantum-well Structures under Different Overgrowth Conditions in Light-emitting Diodes
Date Issued
2011
Date
2011
Author(s)
Wu, Sheng-Pei
Abstract
The objective of this research is to use the methods of high resolution transmission electron microscope (HRTEM) and strain-state analysis (SSA) to compare the nanostructures of InGaN/GaN quantum wells (QWs) under different growth conditions. We find that in a high-indium InGaN/GaN QW light-emitting diodes, the thickness of the p-AlGaN and p-GaN layers can be optimized for maximizing the QW internal quantum efficiency (IQE). During the growths of the p-AlGaN and p-GaN layers, the QWs are thermally annealed to first enhance carrier localization by reshaping the structures of indium-rich clusters before the optimized annealing time is reached. Beyond this point, the carrier localization effect is weakened, leading to lower IQE. The results of SSA in the HRTEM study show the consistent trend.
Subjects
Light-emitting Diodes
LED
InGaN
Transmission Electron Microscopy
Type
thesis
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