Surfactant-mediated epitaxy of high-quality low-doped relaxed germanium films on silicon (001)

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• 作者：Tobias F. Wietler ; Eberhard Bugiel and Karl R. Hofmann
• 关键词：Germanium ; Silicon ; Molecular beam epitaxy (MBE) ; Growth mechanism
• 刊名：Thin Solid Films
• 出版年：2006
• 出版时间：5 June 2006
• 年：2006
• 卷：508
• 期：1-2
• 页码：6-9
• 全文大小：249 K

文摘

Direct growth of relaxed Ge layers on Si(001) substrates was achieved using Sb as a surfactant. Deposition of Ge at substrate temperatures around 670 °C under large Sb flux resulted in complete compensation of lattice mismatch via a regular array of 90° dislocations at the interface. A residual 0.20 % tensile strain is found caused by thermal mismatch between Ge and Si. The density of defects threading through the Ge films is as low as 5 × 10⁷ cm^{− 2}. This is ascribed to an abrupt strain release during the initial micro-rough growth phase, which occurs only under the selected growth conditions. We also observed n-type Sb background doping levels in the Ge layers well below 10¹⁷ cm^{− 3} presumably related to an enhanced Sb surface segregation due to the high growth temperature. Such relaxed Ge films grown by surfactant-mediated epitaxy on Si(001) open attractive perspectives for integration of novel Ge devices into mainstream Si technology.