Optical Analyses of InGaN MQW Light-Emitting Diodes and Raman Spectroscopy Studies on Carbon Nanotubes
Date Issued
2010
Date
2010
Author(s)
Huang, Chien-Lin
Abstract
This thesis mainly divides into two parts: the first part is analyzed the optical properties of InGaN/GaN multi-quantum wells LED structure. The Raman scattering, photoluminescence (PL), photoluminescence excitation (PLE), time-resolved photoluminescence (TRPL) experiments were carried out to study the optical properties; the second part is the studies on carbon nanotubes (CNTs) by Raman spectroscopy.
First, we compared the optical properties with different well widths and different growth time of epitaxial lateral overgrowth GaN layer for an InGaN/GaN quantum well structure. The research reports mentioned in Chapter 3 will give us the information about different well widths effects. From the Photoluminescence, photoluminescence excitation and time-resolved photoluminescence experiments, we can find that the luminescence efficiency is higher and the carrier lifetime is longer for the sample with wider well width. Furthermore, the measurement results of different growth time of epitaxial lateral overgrowth GaN layer for an InGaN/GaN quantum well structure will be discussed in Chapter 4. We can observe that a larger Stokes shift results from longer growth time of epitaxial lateral overgrowth GaN with (112￣2) facets. The experimental results shown here can serve as important clue for the enhancement of the luminescence efficiency in the future optoelectronic devices.
Second, we attend to investigate the Raman scattering spectroscopy and fittings on carbon nanotube (CNT) samples. In Section 5.1 we analyzed the Raman spectroscopy about Cu nanoparticles and microfibers prepared by solid state reaction using carbon nanotube as template. Then we discussed the relation between Raman signals and field emission properties of pure CNT arrays with different growth conditions in Section 5.2. Besides, there were some electron microscope, X-ray diffraction, and X-ray absorption measurements of CNT samples.
Subjects
InGaN MQW Light-Emitting Diodes
Carbon Nanotubes
Raman Spectroscopy
Type
thesis
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