Characteristics of InGaN/GaN Multiple Quantum Wells with Different Growth Temperatures and Zinc Oxide Thin Films Grown on Sapphire
Date Issued
2005
Date
2005
Author(s)
Chin, Shu-Cheng
DOI
en-US
Abstract
In this research, we compare the nanostructure and optical property of four InGaN/GaN multiple quantum well samples with different growth conditions. The quantum wells of three of these samples were grown at different temperatures. The incorporated indium content becomes higher as the growth temperature decreases. The crystalline quality of a sample with a higher indium content becomes worse. Spinodal decomposition is stronger at a lower growth temperature. In addition, the photon emission wavelength is longer in a sample of a growth temperature. In growing the fourth sample, H2 flow was added to the growth chamber in growing barrier layers (undoped GaN). We find that spinodal decomposition is suppressed and indium atoms are well confined in the InGaN layers. From the X-ray diffraction (XRD) results, the crystalline quality of this sample is the best among the four samples. The second part of this research is to study the nanostructures of three ZnO thin films grown on sapphire. We observed that the ZnO thin film changes into rod-like structure at high growth temperature (450 ℃). In this sample, there is an orientation twist (30 degrees) with respect to the c-axis at the interface between ZnO and sapphire. We obtained different electron diffraction patterns between ZnO and sapphire from transmission electron microscopy (TEM) for confirming this twist. The twisted structure reduces the lattice mismatch between ZnO and sapphire, which leads to a lower surface energy. The sample of high-temperature growth has higher photon emission efficiency.
Subjects
氮化銦鎵/氮化鎵多重量子井
氧化鋅薄膜
穿透式電子顯微鏡
InGaN MQWs
ZnO
TEM
Type
thesis
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