利用液相磊晶法於 Si(111)基板上所製備鍺薄膜之特性分析

Characterizations of Ge films grown on Si(111) substrate by liquid phase epitaxy

劉家維(Chia-Wei Liu)

指導教授 ： 溫武義

中原大學/電機資訊學院/電子工程研究所/碩士(2017年)

https://doi.org/10.6840/cycu201700074

摘要

於本研究中我們於Si 基板上利用液相磊晶(LPE)法成長Ge/SiGe 的異質接面結構，而一般所知道的液相磊晶法所成長出來的晶格匹配程度限制在小於 1%以下，但 Si 與 Ge 的晶格不匹配程度為 4.2%，所以若要直接將 Ge 生長在 Si 基板上就必須要多長出一層 SiGe 漸變層。在此研究中，我們利用含Sn達90.2%原子百分比的Sn-Ge溶液於950℃開始LPE成長，並且利用此時Si基板之回溶來提供Si原子的方式，成功地在 Si(111)基板上長出 SiGe 漸變層，使得最終欲在Si(111)基板上成長出純 Ge 層是可能的。透過X光繞射，拉曼散射，掃描電子顯微鏡（SEM），能量分散光譜（EDS）和透射電子顯微鏡（TEM）等分析後確認了所製備的Ge膜品質。從SEM/EDS 的剖面分析顯示所成長出的 SiGe 漸變層中首先Ge 的組成由10 至15%緩慢變化，其間的膜厚達20至35μm，而最後欲得到高Ge組成(>90%)SiGe層的關鍵所在則是須將LPE成長終止於510℃左右。

關鍵字

液相磊晶 ； 鍺

並列摘要

The heteroepitaxial growth of germanium (Ge) on silicon (Si) substrate was conducted using liquid phase epitaxy (LPE). As known, a limitation of lattice mismatch for the epitaxial growth by LPE was reported to be 1%, while that between Ge and Si is high to the degree of 4.1% and therefore the direct growth of Ge on Si substrate is almost impossible for LPE. However, in the present study a self-organized Si1-xGex film growth with a grading composition has been initiated on the Si(111) substrate and which consequently made possible the fabrication of Ge top film on Si(111) substrate by LPE. The quality of Ge films fabricated was characterized by X-ray diffraction, Raman scattering, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and transmission electron microscopy (TEM).
It is found that the use of tin (Sn) as the solvent and the commencement of LPE at 950°C are important origins to induce the growth of compositionally graded Si1-xGex layer. After the growth of a Si1-xGex layer with tardy grading in Ge composition from 10% to 15% within a layer thickness ranging from 20 to 35 μm, a prompt crossover for Ge and Si composition distributions occurred by ramping the temperature to lower than 510°C. This transition favored for the further growth of Ge epilayers with their thickness generally in the range of several μm.
Raman scattering analyses recognized the tensile strain and high compositions of Ge of the Si1-xGex layers obtained. In addition, the TEM cross-sectional images indicated noteworthy the bending behavior of dislocations and a dislocation density as low as 1.2×〖10〗^5cm-2 was achieved for the Ge top layer grown on Si(111) substrate.

並列關鍵字

LPE ； Ge ； Si

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