以分子束磊晶技術在(111)矽基板上選擇性成長鑲嵌氮化銦鎵量子盒的氮化鎵奈米柱陣列

Selective Area Growth of GaN Nanowire Array Embedded with Ga(In)N Quantum Boxes on Si(111) Substrates Using Molecular Beam Epitaxy

吳濬宏(Wu, Chun Hung)

指導教授 ： 鄭克勇

國立清華大學/電機資訊學院/電子工程研究所/博士(2016年)

摘要

本論文研討以分子束磊晶技術於(111)矽基板上選擇性成長鑲嵌氮化銦鎵量子盒的高密度氮化鎵奈米柱。為了探討選擇性成長氮化鎵，首先製作了含有不同遮罩材料的基板。由於其擁有理想的選擇性，氮化鈦奈米洞與氮化鋁奈米柱腳被選為選擇性成長的基板，但是氮化鈦奈米洞在成長奈米柱時出現奈米柱傾斜的現象而被排除。因此，後續的研究都使用氮化鋁種子層進行。接下來，探討氮化鋁種子層的表面型態與厚度對選擇性成長奈米柱品質的影響。透過逐漸升高鋁流量與基板溫度的方式可成長無鋁球聚集之平整且薄的氮化鋁種子層。利用軟性奈米壓印製作高密度氮化鋁柱腳陣列，並將其作為種子進行選擇性成長氮化鎵奈米柱。六角形氮化鎵奈米柱可藉由調變成長溫度與鎵氮流量比實現。選擇性成長氮化鎵奈米柱的品質則透過低溫量測光致發光頻譜進行檢驗。光致發光頻譜顯示有三個主要的峰值：3.41、3.45以及3.47eV。3.471eV波峰是中性施體束縛激子的激發光，而3.41eV寬波峰是堆疊錯誤或是結構缺陷的激發光。3.45eV則被視為極性反轉區交界的激子復合所致發光。最後成長鑲嵌於氮化鎵奈米柱中的氮化銦鎵量子盒，全可見光光譜可藉由改變量子盒成長溫度而改變銦含量達成。

關鍵字

分子束磊晶 ； 氮化鎵 ； 奈米柱 ； 氮化銦鎵 ； 量子盒 ； 選擇性成長

並列摘要

In this study, the selective area growth (SAG) of high-density (2.5×109 cm-2) GaN nanowires (NWs) embedded with Ga(In)N quantum boxes (QBs) on Si(111) substrate by plasma-assisted molecular beam epitaxy are demonstrated. At first, substrates with various masking materials are prepared for SAG GaN growth: TiN nanoholes and AlN nanopedestal array are chosen as SAG substrates for their ideal NW growth selectivity. However, TiN nanoholes failed to provide adequate NW growth selectivity due to titled NWs while growing on Si surface. Thus, AlN seeding layers are used in this study. Next, effects of morphology and thickness of the AlN seeding layer on the quality of SAG GaN NWs are investigated. A thin and smooth AlN seeding layer without forming Al droplets on the surface is achieved by grading the Al flux and growth temperature from low to high during the growth. High-density AlN nanopedestal arrays used as seeds for SAG GaN NWs are fabricated from thin AlN seeding layers using the soft nanoimprint lithography. By adjusting the growth temperature and Ga/N flux ratio, hexagonal shaped SAG GaN NWs are realized. The quality of SAG GaN NWs is evaluated using low temperature photoluminescence (PL) measurements. Three major PL peaks at 3.47, 3.45, and 3.41 eV are detected and identified. The peak at 3.471 eV is related to the neutral donor-bound exciton emission, and the 3.41 eV broadband emission is attributed to stacking faults or structural defects. The 3.45 eV peak is identified as the emission due to exciton recombination at polar inversion domain boundaries of NWs. Finally, Ga(In)N QBs embedded in GaN NWs are grown. The full visible spectrum emission can be realized by tuning In contents of QBs through varying growth temperature of Ga(In)N layers.

並列關鍵字

Molecular beam epitaxy ； GaN ； Nanowire ； InGaN ； Quantum box ； Selective area growth

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