Growth and self-assembly of MnN overlayers on Cu(0 0 1)
- 作者：Xiangdong Liu ; Bin Lu ; Takushi Iimori ; Kan Nakatsuji ; Fumio Komori
- 关键词：MnN ; Self-assembly ; Stress relaxation ; Metastable CaN ; Cu(0 0 1) ; Pd(0 0 1)
- 刊名：Surface Science
- 出版年：2008
- 期刊代码：104_00396028
- 类别：ch
- 出版时间：15 May 2008
- 卷：602
- 期：10
- 页码：1844-1851
- 文件大小：1526 K
摘要
The growth of MnN overlayers on Cu(0 0 1) has been investigated by low energy electron diffraction and scanning tunneling microscopy with emphasis on the morphology evolution with coverage. A striking feature in the growth is the formation of the self-assembled two-dimensional superstructure at the coverage of 0.9 ML. At this coverage, the MnN nano-islands show a square shape and a well-defined size. They are regularly arrayed with a periodicity of (3.5 ± 0.1) nanometer and form a two-dimensional square superstructure. The MnN island superstructure is stabilized by an unconventional short-range mechanism. A structural model has been proposed to explain the self-assembly and the high-quality of the superstructure. To explore possible wide applications of the new self-assembly mechanism, the growths of MnN on Pd(0 0 1) and calcium nitride on Cu(0 0 1) have also been investigated. MnN overlayers on Pd(0 0 1) present a layer-by-layer-like growth behavior, and highly ordered calcium nitride nanostructure is formed on Cu(0 0 1). Simple discussion is made on the conditions under which the novel mechanism leading to the self-assembly of MnN islands can be applied to other systems. We propose that a large lattice misfit between the overlayer and the substrate, low vacancy formation energy for the substrate, moderate interfacial bonding strength, and a large elastic constant for the overlayer compared with the substrate could be important factors for the split growth and self-assembly.