Studies on Optical Properties of InGaN/GaN Multiple Quantum Well of Different Well Widths and Different Thermal Annealing Conditions
Date Issued
2004
Date
2004
Author(s)
Lin, Shih-Chun
DOI
en-US
Abstract
In this research, optical characterization results of five InGaN/GaN multiple quantum well structures and their thermal annealing effects are reported. First, we present systematical results of the as-grown samples of the same indium content but different quantum well widths. The photoluminescence (PL) peak positions and internal quantum efficiencies of the samples show different behaviors between three temperature ranges. From time-resolved PL (TRPL) measurements, we can see that PL decay times become longer with increasing well width. This trend can be attributed to stronger carrier localizations and larger piezoelectric fields in increasing well width. Then, we conduct post-growth thermal annealing on our samples of different well widths at 800 ℃ for 10 min with different cooling rates. Base on the results of PL, photoluminescence excitation (PLE) and TRPL measurements, thermal annealing with the slow cooling rate leads to the blue shift of PL peak, higher radiative efficiency, and longer PL decay time. However, in the samples with the fast cooling rate, we observe the red shift of PL peak and radiative efficiency degradation. The strain-state analysis results, based on transmission electron microscopy, show the consistent trends. The quantum-dot like nano-structures and the interfaces of quantum wells change with different thermal annealing conditions.
Subjects
氮化銦鎵
量子井
氮化鎵
GaN
QW
InGaN
Type
thesis
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