Strain relief: Mainspring of Ge semiconducting nanostructures growth on LaAlO₃(0 0 1)

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• 作者：Didier Dentel^a ; ^{didier.dentel@uha.fr} ; Hussein Mortada^a ; Mickael Derivaz^a ; Jean-Luc Bischoff^a ; Emmanuel Denys^a ; Francisco M. Morales^b ; Miriam Herrera^b ; J.M. Má ; nuel^b ; R. Garcí ; a^b
• 关键词：Lanthanum aluminate ; High-魏 dielectrics ; Semiconductor&ndash ; insulator interfaces ; Germanium ; Single crystal epitaxy
• 刊名：Acta Materialia
• 出版年：2012
• 期刊代码：1_13596454
• 类别：ms
• 出版时间：March, 2012
• 卷：60
• 期：5
• 页码：1929-1936
• 文件大小：1004 K

摘要

We report on the initial growth mechanisms of Ge on LaAlO₃(0 0 1), a crystalline oxide with a high dielectric constant (high-魏 material). Chemical and structural properties were investigated in situ, through X-ray photoelectron spectroscopy and reflection high-energy electron diffraction, and ex situ by using high-resolution transmission electron microscopy. Ge was deposited by molecular beam epitaxy at 600 掳C on a c(2 脳 2) reconstructed LaAlO₃(0 0 1) surface. At this temperature, a Volmer-Weber growth mode is observed due to a lower LaAlO₃(0 0 1) surface free energy. It is characterized by the immediate formation of crystalline nano-islands. The Ge islands are relaxed and present an abrupt interface with the substrate. Some of them exhibit a preferential relationship in their heteroepitaxy, where the Ge(0 0 1) planes are parallel to the LaAlO₃(0 0 1) ones, but rotated by 45掳 in the [0 0 1] direction. An additional rotation of 6掳 with respect to the growth axis is also observed, which compensates partially for the strain produced by the high lattice parameter mismatch (鈭?%) between the semiconductor and the oxide.