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原子表面扩散的对称破缺对二维岛形成的控制

ISLAND SHAPE SELECTION CONTROLLED BY ATOMIC EDGE-TO-CORNER DIFFUSION

  • 摘要: 文章阐述了当CO吸附改变时Pt/Pt(111)同质外延单层岛的形状的微观选择机制,即岛的取向由沉积原子的边-角扩散运动的不对称性惟一决定.对没有CO介入的理想真空生长情况,衬底温度不能改变三角形岛的取向.CO的吸附反转了边-角扩散运动的不对称性,从而使岛的取向发生变化.

     

    Abstract: The microscopic selection mechanisms of single-layer island shapes in Pt(111) homoepitaxy with or without minute amounts of CO adsorbate have been investigated theoretically. For clean growth, only triangular islands of a fixed orientation are obtained within a wide range of growth temperatures, with the orientation uniquely determined by a disparity in the rates of atom supply to an island corner site from the two island edges defining the corner. This novel picture is further corroborated by growth predictions in the presence of CO, whose preferential decoration of one type of the island edges reverses the intrinsic rate disparity for atom supply, thereby inverting the island orientation.

     

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