銻與氫於InAs/GaAs(001)分子束磊晶之表面活性劑效應

Antimony and Hydrogen Surfactant Effect on the Groth of InAs/GaAs(001) by Molecular Beam Epitaxy

安德列(Andrey Victorovich Katkov)

指導教授 ： 李志浩 ； 祁錦雲

國立清華大學/原子科學院/工程與系統科學系/博士(2013年)

摘要

The interest in the InAs/GaAs(001) hetero-structure is caused by its potential device applications such as quantum dot based infrared laser diodes emitting in 1.3μm spectral range and infrared photo-detectors. High electron mobility of InAs makes this material a potential candidate for high-speed channel in the metal-oxide semiconductor field-effect transistor. In addition to multiple device applications, high lattice mismatch between InAs and GaAs materials (7.2%) makes InAs/GaAs hetero-structure an interesting object from fundamental crystal growth approach.
The first part of this thesis deals with the effect of monolayer level amount of antimony pre-deposited on the bare GaAs(001) surface prior to InAs growth in In-rich mode. Two different types of energy relaxation mechanisms are demonstrated depending on the presence of antimony pretreatment in InAs/GaAs(001) heterosystem. In-situ observations of reflection of high-energy electron diffraction pattern indicate that, as its thickness increases, relaxation of InAs layer grown on the Sb-induced template takes place through the faceting (or Stranski-Krastanov growth mode). Energy relaxation in the Sb-free case takes place through formation of Lomer type edge dislocations at the InAs/GaAs interface, and the InAs growth mode follows layer-by-layer Frank - van der Merwe mechanism according to multiple observations reported by other research groups. A possible model based on the surface energy consideration is proposed in order to explain this behavior.
The second part of the thesis describes the effect of irradiation by hydrogen plasma during growth on the optical properties of InAs based quantum dot structure and its optical properties stability after high temperature annealing. In contrast to the majority of studies published to date, where atomic hydrogen is formed by high temperature cracking of molecular hydrogen on the tungsten filament, industrial made radio-frequency hydrogen plasma source made by EPI (now VEECO) has been used in this work. In addition to very efficient low temperature surface oxide desorption from the GaAs(001) substrate prior to starting growth, we found that room
temperature photoluminescence intensity from InAs based quantum dot structure increases by about an order of magnitude with the use of H-assisted growth, compared with H-free run. The combination of low temperature photoluminescence and plane view transmission electron microscopy technique leads us to conclude that the use of hydrogen plasma during growth significantly improves uniformity of InAs quantum dots as well.

關鍵字

分子束磊晶 ； 化合物半導體 ； 活化劑 ； 氫缺陷鈍化

並列摘要

InAs/GaAs(001)異質結構有許多重要的元件應用，如在砷化鎵基板製作
1.3微米量子點雷射及量子點紅外光電探測器。高電子遷移率的InAs亦可應
用於高速的金屬氧化物半導體場效應晶體管(MOSFET)。除了元件應用外
，砷化銦和砷化鎵材料（7.2％）之間的高晶格失配在InAs/GaAs異質結構
磊晶時產生的效應與現象亦是有趣的基礎研究課題。
本論文主要是探討於分子束磊晶(MBE)時銻原子與氫原子的效應。論
文的第一部分，探討銻原子在GaAs(001)表面之預處理對成長於其上之InAs
生長模式的影響。實驗觀察到不同的銻預處理過程會導致兩種不同類型的
晶格能量弛豫機制，由原位的反射高能電子衍射圖案的觀測顯示，當厚度
增加時，在不同Sb-產生的模板上生長之InAs層其能量弛豫機制是通過為形
成微晶面 (faceting) 的方式進行（亦稱Stranski-Krastanov的生長模式）。而在無銻的情況下InAs/GaAs磊晶之弛豫機制，是在介面形成魯姆爾
(Lomer) 型位錯的法蘭克-凡德爾莫維 (Frank - van der Merwe) 成長機制。後一種機制與其他研究小組的實驗報告類似。我們提出了一個表面能量的
模型來解釋這兩種能量弛豫現象。論文的第二部分探討了在生長時加上氫等離子體輻照對材料光學性能的影響。本實驗所用之氫輻照與大多數研究不同，一般使用以鎢燈絲高溫裂解氫分子形成之氫原子，而本實驗是使用RF頻率氫等離子體電漿源(美
國VEECO製造)。實驗發現，在高溫退火後InAs量子點結構及光學性能之
變化甚微，但在發光性能上，氫輔助生長的量子點，相比於無
H處理的樣品，其室溫光激發發光強度增強一個數量級。此外本實驗又發
現氫等離子體輻照是一非常有效的，低溫GaAs(001)表面氧化層清除步驟
。又經由低溫光激發和平面視透射電鏡技術的觀察，發現在生長過程的使
用氫等離子體照射顯著提高了InAs 量子點及均勻性

並列關鍵字

Molecular Beam Epitaxy ； Compound semiconductor ； Surfactant ； Hydrogen defect passivation

參考文獻

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