砷化銦(鎵)自我組成量子點內成分組成與成長溫度之研究

Composition Distribution and Growth Temperature in In(Ga)As Self-Assembled Quantum Dots

楊富強(Fu-Chiang Yang)

指導教授 ： 詹國禎

國立臺灣大學/電機資訊學院/光電工程學研究所/碩士(2004年)

https://doi.org/10.6342/NTU.2004.02185

摘要

為了能夠模擬砷化銦/砷化鎵量子點會因為量子點因不同的成長溫度和後被覆蓋層 (overgrowth layer)的影響使得鎵成分跑進砷化銦量子點內的情況會是如何?此模擬必須要要能夠考慮到量子點內不同位置的成分變化。因此，除了要考慮到非均勻成分對應變分布的影響，同時也要考慮到使用8能帶k∙p矩陣下因成分的不同而造成微小的數值變化。
砷化銦/砷化鎵量子點的光電特性藉由光致螢光光譜(PL)實驗來研究。樣品(C1424和C1520)是利用氣態分子束磊晶成長術的「史傳斯基-克拉斯坦諾夫」(Stranski-Krastanov)長晶模式在無摻雜(100)面的基板上。同樣以0.085ML/s 的低量子點成長速率以及在成長砷化銦量子點之後蓋上一層砷化銦鎵(InGaAs)材料,稱為後被覆蓋層,唯一的差別只在於量子點和後被覆蓋層的成長溫度不同，C1424(485℃)和C1520(495℃)。由於後來又都是加上一層低溫(480℃)成長的砷化鎵，故兩者最大的變因就在於量子點的成長溫度，而其中所造成的影響就在於鎵成份進入砷化銦量子點的多寡。
在這篇論文,模擬非均勻量子點模型成功的被建立起來，同時模擬時在不失良好準確度的情形下能快速的模擬。此模擬是利用計算應變的「continuum mechanical」(CM)模型和8能帶k∙p矩陣,同時也和另外一種利用計算應變的「valence force field」(VFF)模型加上假位能(pseudpotential)的模擬結果來做比較。而從結果比較來看,我們的模擬更能接近真實的量子點情形。同時，半截面金字塔形狀且具有不同成分曲線的量子點在能夠在理論上探討，並且能夠確認且量化成長溫度主宰量子點從基底開始的成分分佈,後被覆蓋層則影響從量子點頂端開始的成分分布,而且因為其基底成分的影響進而影響到量子點的直徑大小。

關鍵字

砷化銦(鎵) ； 量子點

並列摘要

For checking how much Ga component enter InAs/GaAs quantum dots (QDs) from GaAs substrate due to growth temperature of QDs and composition of overgrowth layer, the simulation must be considered composition variation in different position of QD. For this reason, not only consider the strain distribution due to nonuniformed composition, but also must be very careful to handle the tiny variation due to difference of composition in eight-band k∙p model.
The samples (C1424 and C1520) were grown by the gas-source molecular-beam epitaxy in the Stranski–Krastanov growth mode on an undoped GaAs (100) substrate. With overgrowth InGaAs layer and low QD growth rate about 0.085 ML/s, the only difference is growth temperature of QDs and overgrowth layer in C1424 (485°C) and C1520 (495°C). Because of the low temperature (480℃) GaAs undoped layer on top, the ultimate difference is the growth temperature of InAs QDs, and it affect the Ga component how much enter InAs QDs.
In this paper, the simulation used continuum mechanical model (CM) to calculation strain and eight-band k∙p model is compared with others used valence force field model (VFF) and pseudpotential method. From the results compared, our simulation is much closer the actuality of QDs. Meanwhile, the electronic properties of truncated pyramidal shaped InAs/GaAs QDs kept in different composition profile are investigated theoretically and confirmed composition distribution from base of QDs dominated by growth temperature, in the other way, the overgrowth layer dominate the composition distribution from top of QDs, at the same time, the size of QDs are affected by composition distribution from base of QDs..

並列關鍵字

Quantum Dots ； In(Ga)As

參考文獻

[2] L. Esaki and R. Tsu, IBM J. Res. Develop. 14, 61.

[3] L. L. Chang, L. Esaki, and R. Tsu, Appl. Phys. Lett. 24, 593 (1974).

[4] R. Dingle. Festkorperprobleme 15, 21 (1975).

[5] D. A . B. Miller, D. S. Chemla, P. W. Smith, A. C. Gossard, and W. T. Tsang, Appl. Phys. B 28, 96 (1982).

[6] D. A . B. Miller, D. S. Chemla, D. J. Eilenberger, P. W. Smith, A. C. Gossard, and W. T. Tsang, Appl. Phys. Lett. 41, 679 (1982).