不同矽摻雜條件之氮化銦鎵/氮化鎵多重量子井奈米結構之穿透式電子顯微術分析研究

楊志忠臺灣大學：電子工程學研究所陳孟谷Chen, Meng-KuMeng-KuChen2007-11-272018-07-102007-11-272018-07-102004http://ntur.lib.ntu.edu.tw//handle/246246/57236在本研究中，我們探討了在不同條件下氮化銦鎵/氮化鎵多重量子井的奈米結構，包括不同銦原子濃度、不同矽摻雜區域與不同矽摻雜濃度等條件。我們也研究了熱退火與電子束照射對奈米結構所造成的效應。研究樣品的方法包括材料與光學分析，材料分析的方法包括有高解析度穿透式電子顯微術與應變分析，光學分析的方法包括有激發螢光光譜與激發螢光吸收光譜。在應變分析中，我們可以清楚地觀察到在不同摻雜條件下其奈米結構的變化。一般而言，在矽摻雜的樣品中會形成較多的銦聚集結構，尤其是摻雜在位障層中的樣品更明顯。而且銦聚集的現象也會隨著矽摻雜濃度增加趨於明顯。光學的測量也證實矽摻雜的確可以改善載子的結合效率。從這樣的量測結果可歸因於在矽摻雜的樣品中有較強的載子侷限和應力的釋放。我們也觀察到熱退火可以改變其奈米結構及其光學特性。最後，我們也發現量子井在幾分鐘以內的電子束照射下並不會明顯改變其奈米結構。In this research, we have investigated the nanostructures of InGaN/GaN multiple quantum wells (MQWs) with different indium concentrations, different silicon doping regions, and different silicon doping concentrations. We also studied the effects of post-growth thermal annealing and electron beam exposure on the nanostructure. The methods used for studying our samples, including material and optical analysis methods. Material analysis methods include high-resolution transmission electron microscopy (HRTEM) and the strain-state analysis (SSA). Optical analysis methods include photoluminescence (PL) and photoluminescence excitation (PLE). From strain-state analysis (SSA) results, we could clearly see the differences of nanostructures between the samples of different doping conditions. Typically, more clusters were formed in Si-doped samples, particularly in the barrier-doped sample. Also, more clusters can be formed by increasing silicon doping concentration. Optical measurements showed that with Si-doping, the recombination efficiency could be improved. Such an improvement could be attributed to stronger carrier localization (more clusters formed) and better strain relaxation (weaker quantum-confined stark effect) upon silicon doping, particularly doping in barriers. We have observed that thermal annealing could change the nanostructures and optical properties of InGaN/GaN MQWs. We have found that electron beam exposure for a few minutes may not change the nano-structure of an InGaN/GaN QW sample.Contents Chapter 1 Introduction 1.1 Applications of Nitride-Based Materials…………………………..1 1.2 Basic properties of Nitride Compounds. …….……………………3 1.2.1 Crystal Structure of Nitrides….…………………………….3 1.2.2 Crystal Growth of Nitrides………………….……………...4 1.2.3 Substrates for Nitride Epitaxy……………………………...6 1.2.4 Defects in Nitrides………………………………………….7 1.3 Review on the Characteristics of InGaN/GaN Structures…………8 1.3.1 InGaN Alloy………………………………………..………8 1.3.2 Strain Effect………………………………………………...8 1.3.3 Piezoelectric Field………………………………………….9 1.3.4 Spinodal Decomposition and Phase Separation…………..11 1.3.5 Indium Aggregation and Quantum Dot-like Structure……12 1.4 Effect of Silicon-doping in InGaN Quantum Well Structures…....14 1.5 Research Motivation and Research Problems……….………..….17 Chapter 2 Analysis Methods 2.1 Specimen Preparation of Cross-section TEM……………………28 2.2 Introduction to the Transmission Electron Microscopy ……........31 2.2.1 Basis for Transmission Electron Microscopy……………31 2.2.2 High Resolution Transmission Electron Microscopy (HRTEM)………………………………………………..33 2.3 Strain-state Analysis…………...…………………………………35 2.4 Optical Analysis…………………………………………………37 2.4.1 Photoluminescence (PL)………………………………....37 2.4.2 Photoluminescence Excitation (PLE)…………………..38 Chapter 3 Material and Optical Analysis Results of InGaN/GaN Multiple-quantum-well Samples of Different Indium Concentrations and Different Doping Regions 3.1 Sample Descriptions and Measurement Conditions………........48 3.2 Material Analysis Results …………………….………………...49 3.3 Optical Analysis Results…………………………………..……...52 3.4 Discussions…………………………………………….….……...54 3.5 Conclusions……………………………………………………....58 Chapter 4 Material and Optical Analysis Results of InGaN/GaN Multiple-quantum-well Samples of Different Silicon Doping Concentrations and Studies on the Effects of Thermal Annealing and Electron Beam Exposure 4.1 Sample Descriptions and Measurement Conditions..……………73 4.2 Effects of Different Silicon Doping Concentrations in GaN Barrier……………………………………………...……………74 4.3 Effects of Thermal Annealing…………………………………….77 4.4 Effects of Electron Beam Exposure………………………………78 Chapter 5 Conclusions References……………………………………………………..925975452 bytesapplication/pdfen-US量子井氮化銦鎵氮化鎵quantum wellGaNInGaN不同矽摻雜條件之氮化銦鎵/氮化鎵多重量子井奈米結構之穿透式電子顯微術分析研究Transmission Electron Microscopy Studies of InGaN/GaN Multiple Quantum Well Nano-Structures of Different Silicon Doping Conditionsthesishttp://ntur.lib.ntu.edu.tw/bitstream/246246/57236/1/ntu-93-R91943101-1.pdf