利用快速熱熔磊晶鍺異質成長砷化鎵材料於矽基板

Epitaxy of GaAs on Rapid-Melt-Growth Ge on Silicon Substrate

洪偉誠(Wei-Cheng Hung)

指導教授 ： 李明昌

國立清華大學/電機資訊學院/光電工程研究所/碩士(2012年)

摘要

近年來，矽與砷化鎵整合技術應用於電子元件或光學元件上一直以來都是一個經常被拿來研究的課題，舉例來說利用砷化鎵作為基底的三五族量子井場效電晶體，或三五族紅外光雷射，文獻上都已成功做出且也不錯的特性表現。但基於兩種材料本質上4%的晶格常數、60%熱膨脹係數的差異以及晶格結構的差異，使矽與砷化鎵整合有一定的難度。一般常用方法如晶圓接合法，可直接將鍺晶圓和矽晶圓對接，不需高溫的鍵結，但缺點為太浪費材料，且接合時，晶圓表面輪廓不易控制。另一種方法是利用成長漸變式的矽鍺緩衝層藉由緩衝層間接成長砷化鎵於矽上，此法需要較特殊的製程處理和儀器，磊晶後的矽鍺緩衝層會很厚且需要高溫長時間的退火，才能達到元件所需高品質單晶鍺，此高熱預算會降低元件表現，另外太厚的鍺緩衝層也會影響III-V雷射在通訊波段1.3um的發光效率。
回顧文獻，使用快速熱熔磊晶法可以保證所長的鍺為高品質單晶，且可以輕易控制厚度及可複製晶向，本文試圖利用快速熱熔磊晶法在矽基板上磊晶鍺，取代矽鍺漸變的方法，做為成長砷化鎵前的緩衝層，改善鍺緩衝層太厚且高熱預算過高的問題，並實際利用金屬有機化學氣相沉積系統異質成長砷化鎵於矽基板上，並利用SEM、AFM及TEM、光激發光(PL)光譜觀察表面型態、粗糙度及結晶狀態與缺陷。

關鍵字

鍺 ； 砷化鎵 ； 液項磊晶 ； 有機金屬化學氣相沉積

並列摘要

GaAs/Si integration receives a lot of attention for both electronic and photonic devices. For example, GaAs/Si-based III-V QWFET and III-V lasers have been demonstrated with superior performances. However, pure GaAs grown on Si is critical due to the lattice mismatch (4%) between these two semiconductors as well as different thermal expansion coefficients. Direct wafer or die bonding of GaAs onto Si wafers is the way that can integrate GaAs on Si. However, removing the bonded substrates could be a waste of material. Furthermore, surface topography between the bonding interfaces often affects the process yield very much. Another approach for GaAs on Si is prior epitaxial growth of Ge/GexSi1-x buffer layer between Si and GaAs, which usually requires special process techniques and the Ge/GexSi1-x buffer layer is usually very thick. In addition, Ge/ GexSi1-x epitaxial growth often requires a high-temperature process condition to achieve high crystal quality. Consequently, the resultant thermal budget and thicker Ge buffer layer could degrade the III-V laser properties at 1.3um wavelength.
Previously, rapid melt growth (RMG) of Ge on insulator showed a promising way for integration of high-quality thin Ge on silicon substrate. One characteristic of the RMG method is that the crystal orientation of the growth Ge is a complete replica of the substrate Si and the thickness can be controlled to be very thin. In this paper, we try to use the RMG Ge to substitute the Ge/GexSi1-x buffer layer for epitaxy of GaAs. We use MOCVD to epitaxy GaAs on RMG-Ge. Then we use SEM and AFM to observe the surface morphology and the roughness and use TEM and PL measurement to characterize the crystal quality.

並列關鍵字

Ge ； GaAs ； RMG ； MOCVD

參考文獻

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