<利用有機金屬化學氣相沉積法直接成長砷化銦/砷化鎵異質結構於鍺基板>

Abstract

本研究論文，主要探討影響高品質的砷化銦/砷化鎵異質結構成長於鍺基板上之數種變因，其中包含成長溫度、成長時間及五三比等效應。由實驗結果證實，在高溫成長的環境下(> 420 ℃)，砷化銦島狀結構偏好以水平方向成長。另一方面，砷化銦島狀結構的縱向成長速率，也會隨著成長時間的增加(> 20秒)，而有所提升。因此，在較低的成長溫度與較短的成長時間下，將可取得高密度、均勻的砷化銦島狀結構之分佈，於砷化鎵/鍺異質結構上。再者，實驗發現對於五三比的適當調控，確實得以提高於砷化鎵/鍺之異質結構上的砷化銦磊晶品質；然而，其五三比之調變，並非單純控制成長薄膜砷化銦結構的唯一關鍵因素。因此，在砷化銦/砷化鎵/鍺異質結構之成長，透過運用特定的成長參數條件，形成大量規律性90°錯位差排，藉此將存在於砷化銦/砷化鎵異質界面處的錯位應變，有效釋放(應變釋放率~90%)。另外，當砷化銦的磊晶厚度超過其臨界值時，我們發現形成90°錯位差排的條件，與當中於介面處的銦原子分布有所相關。這些結果說明，藉由形成大量的規律性90°錯位差排之砷化銦磊晶界面於砷化鎵上，可有效降低砷化銦的表面能與應變能，因而在材料成長的過程中，幫助薄膜砷化銦磊晶成長於砷化鎵/鍺異質結構上。

The growth of high quality InAs/GaAs heterostructure grown on Ge substrate is influenced by several factors, such as growth temperature, growth time, and V/III ratios. We demonstrate that, at high growth temperature (> 420 ℃), InAs islands favor lateral-growth domain during material growth. On the other hand, the vertical-growth rate of InAs islands is increased with the increase of growth time (> 20 seconds). It is shown that uniform and concentrative InAs island distribution on GaAs/Ge heterostructure can be achieved when shorter growth time and lower substrate temperature are adopted. Furthermore, it is demonstrated that very tight control of V/III ratios can improve the quality of InAs epitaxy on GaAs/Ge heterostructure. However, the factor of V/III ratios is not the only key factor controlling InAs thin-film growth. Therefore, under specific growth parameters, the periodic 90° misfit dislocations can be generated at the InAs/GaAs interface to relax the misfit strain (relaxation degree ~ 90%) during the InAs/GaAs/Ge heterostructure growth. Besides, we also found that a 90° misfit dislocation formation is closely related to indium atom distribution at the interface when InAs epitaxial thickness excesses critical thickness. These results demonstrate periodic 90° misfit dislocations formed at the InAs epitaxy interface with GaAs can effectively reduce the InAs between surface energy and strain energy during material growth and assist in the formation of InAs thin film on GaAs/Ge heterostructure.