以液相磊晶法進行自我調變Ge-on-Si磊晶研究及特性分析

The study and application for Self-modulated Ge/SiGe/Si structure by liquid phase epitaxy

連承胤(Chen-Yin Lian)

指導教授 ： 温武義

中原大學/電機資訊學院/工業與系統工程研究所/碩士(2016年)

https://doi.org/10.6840/cycu201600769

摘要

我們將利用液相磊晶成長異質接面的Ge/SiGe結構在Si基板上，而眾所共知液相磊晶其成長之晶格匹配程度限制在1%以下，但Si與Ge的晶格不匹配程度為4.1%，所以要直接將Ge成長在Si基板上就必須多成長出一層SiGe漸變層。然而在此實驗中，我們已經成功的成長出SiGe漸變層在Si(111)基板上，所以之後要成長出純Ge層在最上面是有可能的。
此篇我們將用SEM來探討Si1-xGex成長在Si基板上的晶格不匹配的機制，用EDS調查成長出來的薄膜之組成並用TEM分析其晶格結構。SEM/EDS的剖面分析圖顯示我們所成長出來的SiGe漸變層中Ge佔10至15%之厚度高達20至35um，而其中Si與Ge的比例產生巨變是發生降溫超過在510度的地方。
我們也發現，用Sn當溶媒Ge當溶質，並且成長溫度在950度且Si的來源由基板提供是對於能成長出SiGe漸變層很關鍵的元素。特別是若要成長高Ge含量之Si_(1-x) Ge_x(x>9)層，液相磊晶其成長溫度必須降到一定的溫度而此溫度可由Ge-Sn相圖得到。

關鍵字

液相磊晶 ； 自我調變

並列摘要

The heteroepitaxial growth of high germanium (Ge) silicon 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 high Ge composition Si1-xGex 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, which consequently made possible the fabrication of Ge top film on Si(111) substrate by LPE.
In this work the LPE growth mechanism of mismatched Si1-xGex on Si is discussed based on the film morphologies observed by scanning electron microscopy (SEM), elemental distributions analyzed by energy dispersive spectroscopy (EDS), and crystalline structure examined by transmission electron microscopy (TEM). SEM/EDS cross-sectional analyses displayed that 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 high Ge composition Si1-xGex epilayers with their thickness generally in the range of several μm.
It is found that the use of tin (Sn) as the solvent and Ge as the solute to form a Sn-rich Ge-Sn growth solution, accompanied by the commencement of LPE at 950°C to introduce Si species from substrate are important origins to induce the growth of compositionally graded Si1-xGex layer. In particular, a high Ge composition Si_(1-x) Ge_x layer with x > 0.9 can be achieved by terminating the LPE growth at an appropriate temperature suggested by the Ge-Sn phase diagram and thus the corresponding growth mechanism is well illustrated based on the same phase diagram.

並列關鍵字

LPE ； Ge-on-Si

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