以有機金屬化學氣相磊晶法成長1.3微米砷化銦/砷化鎵量子點異質結構與砷化銦/砷化鎵量子點共振腔發光二極體

Growth of 1.3μm InAs/GaAs Quantum Dot Heterostructure and InAs/GaAs Quantum Dot Resonant Cavity Light-Emitting Diodes by Metalorganic Chemical Vapor Deposition

黃坤富(Fun-Fu Huang)

指導教授 ： 吳孟奇

國立清華大學/電機資訊學院/電子工程研究所/博士(2006年)

https://doi.org/10.6843/NTHU.2006.00360

摘要

本篇論文的主要目的是以有機金屬化學氣相磊晶法成長砷化銦/砷化鎵量子點異質結構與製作1.3微米砷化銦/砷化鎵量子點共振腔發光二極體並探討其特性。
目前自聚性量子點異質結構是藉由「史傳斯基-克拉斯坦諾夫」磊晶模式成長，且其發光與結構特性由磊晶參數決定。因此，我們首先研究磊晶溫度與磊晶速度對砷化銦量子點的影響。當磊晶溫度從540降到480℃時，我們發現較低的磊晶溫度較易形成量子點，且在500℃下成長之量子點有最佳的發光特性，其發光波長可達1.3微米，半高寬為30.8毫電子伏特。在改變砷化銦量子點的磊晶速度的實驗中，較低的磊晶速度形成較多的不規則島狀物，而這些島狀物可能產生缺陷，造成發光效率下降。
之後，我們成功地製作1.3微米發光的砷化銦量子點共振腔發光二極體。我們以一層砷化銦量子點埋藏於砷化鎵中作為共振腔發光二極體的主動層，再以一對氮化矽/氧化矽與20對砷化鋁鎵/砷化鎵分佈布拉格反射層作為共振腔發光二極體的上下層鏡面，其中，利用介電質材料之布拉格反射層作為共振腔發光二極體的上層鏡面可避免砷化銦量子點在高磊晶溫度下發生互混效應而造成輸出光功率下降。砷化銦量子點共振腔發光二極體於室溫下，其發光波長可達1.32微米，半高寬為14毫電子伏特，在注入電流為100毫安培時其輸出光功率為28毫瓦。
最後，為了進一步提升砷化銦量子點的密度與均勻性，我們將砷化銦量子點成長於砷化銦鎵應力緩衝層上並研究其特性。相較於砷化銦量子點成長於砷化鎵上，我們發現將砷化銦量子點成長於砷化銦鎵應力緩衝層上有較高的密度與較佳的均勻性，符合我們的預期。在低溫(80K)下砷化銦量子點的光激螢光譜圖中，在最強激發光功率下，由於填態效應，我們觀察到砷化銦量子點的第一、第二激發態出現於高能側；在變溫下量測成長於砷化銦鎵應力緩衝層上之砷化銦量子點的光激螢光譜圖，發現砷化銦量子點的能隙依循瓦希尼經驗公式隨溫度而變化，而砷化銦量子點光激螢光強度隨溫度上生而下降的「熱熄」現象，可能與缺陷有關。之後，我們製作p-i-n結構的砷化銦量子點/砷化銦鎵應力緩衝層邊射型發光二極體其外部量子效率為0.024%，發光波長可達1330奈米。

關鍵字

有機金屬化學氣相磊晶法 ； 砷化銦量子點 ； 共振腔發光二極體

並列摘要

The main intention of this thesis is growth and characterization of InAs/GaAs quantum dot (QD) heterostructure with 1.3 μm emission wavelength and fabricates 1.3 μm-emitting InAs/GaAs quantum dot resonant cavity light-emitting diode (QD RCLED). The QD heterostructure have been successfully realized via Stranski-krastanow growth mode, and the structural and the optical characteristics of InAs QDs determinate by growth parameters. Firstly, we investigate the growth-temperature and growth-rate effect of InAs QDs on GaAs substrate grown by low pressure metalorganic chemical vapor deposition (LP MOCVD). The lower growth temperature makes for the formation of InAs QDs with different growth temperatures, and the optimum optical characteristic of InAs QDs is grown at 500℃, which can extend the emission wavelength to 1.3 μm with strongest photoluminescence (PL) intensity, the narrowest full width at half maximum of 30.8 meV as compare to grow at other growth temperatures. In various growth rates tuning experiment, lower growth rate forms more irregular relaxed islands, and the weaker PL peak intensity is shown in the PL spectrum.
Secondly, InAs QD resonant cavity light-emitting diode with 1.32 μm-emitting has been successfully fabricated at room temperature in our work. The active medium of QD RCLED was a single-sheet 3.0 ML InAs QDs inserted in GaAs matrix grown by metalorganic chemical vapor deposition. The epitaxial AlGaAs/GaAs pairs and one dielectric SiO2/Si3N4 pair as distributed Bragg reflectors (DBRs) are fabricated as the bottom and top mirrors of QD RCLEDs, which can provide high cavity factor and avoid the In/Ga intermixing of InAs QD during fabricating the top mirror. The InAs/GaAs QD RCLEDs present an emission wavelength of 1.318 mm, a narrow full width at half maximum in the electroluminescent spectrum of 14 meV at 20 mA, a high Q factor of 73.9, a low redshift rate with injection current of 0.033 nm/mA, and a light-output power of 28 mW at 100 mA.
Finally, we investigate the structural and the optical characteristics of InAs QDs grown on InGaAs strained buffer layer (SBL). The InAs QD density can increase to 3.5 x 1010 cm-2 as InAs QD deposited on InGaAs SBL, and the QD size uniformity is better than InAs QD directly deposited on GaAs layer. Under highest excited density at low temperature, PL spetra shows the ground, first and second states of InAs QDs due to the state-filling effect; the temperature-dependent PL shows the PL peak energy has a redshift following the Varshni relation and an unusual temperature dependence of linewidth which first reduces and then increases with increasing temperature for the InAs QDs on the InGaAs SBL. The PL thermal quenching arises from the carrier escape of the dots to nonradiative recombination centers like defects. The single sheet InAs QD/ InGaAs SBL edge-emitting p-i-n LEDs is emitting at 1330 nm with an external quantum efficiency of 0.024% at room temperature.

並列關鍵字

MOCVD ； InAs QD ； RCLED