物理化学学报 >> 2008, Vol. 24 >> Issue (12): 2185-2190.doi: 10.3866/PKU.WHXB20081207

研究论文 上一篇    下一篇

W(100) c(2×2)表面的STM图像

陈文斌, 陶向明, 尚学府, 谭明秋   

  1. 浙江大学物理系, 杭州 310027
  • 收稿日期:2008-06-10 修回日期:2008-08-19 发布日期:2008-12-04
  • 通讯作者: 陶向明 E-mail:taoxmm@tom.com

STM Images of a W(100) c(2×2) Surface

CHEN Wen-Bin, TAO Xiang-Ming, SHANG Xue-Fu, TAN Ming-Qiu   

  1. Department of Physics, Zhejiang University, Hangzhou 310027, P. R. China
  • Received:2008-06-10 Revised:2008-08-19 Published:2008-12-04
  • Contact: TAO Xiang-Ming E-mail:taoxmm@tom.com

摘要: 用基于第一性原理的密度泛函理论研究了W(100) c(2×2)再构表面的表面弛豫以及扫描隧道显微镜(STM)图像和衬底偏压的关系. 计算所得到的表面原子沿[-110]方向的畸变位移δ为0.027 nm, 畸变能⊿E为80.6 meV·atom-1, 表面原子的弛豫分别为-7.6%(⊿d12/d0)和+0.8%(⊿d23/d0), 功函数Φ为4.55 eV. STM图像模拟表明, 由于表面原子沿[-110]方向的位移, 会导致出现平行于[110]方向的亮暗带状条纹. STM图像中突起所对应的并不是表面或次表面的钨原子, 而是zig-zag型W 原子链中线位置; 而STM暗区对应于原子位置畸变形成的相邻zig-zag型W原子链中间区域. 当衬底负偏压时, STM针尖典型起伏高度大约在0.008-0.013 nm之间; 而当衬底正偏压时, 针尖起伏高度在0.019-0.024 nm之间变化.

关键词: W(100) c(2×2)表面, Zig-zag畸变, STM图像

Abstract: Scanning tunneling microscope (STM) images and surface relaxations of a reconstructed W(100) c(2×2) surface have been investigated by density functional theory calculations. The distorted displacement (δ) of a tungsten atom along [110] was 0.027 nm. The distortion energy was 80.6 meV·atom-1 and the relaxations of the W(100) c(2×2) surface was calculated to be -7.6% for ⊿d12/d0 and +0.8% for ⊿d23/d0. The surface work function (Φ) was 4.55 eV. Calculated STMimages of the W(100) c(2×2) surface displayed the following unusual features: protrusions in the STM image along the [110] axis are in the middle of a zig-zag chain of tungsten atoms while the dark regions in STM images correspond to valleys between neighboring zig-zag chains. These are due to surface reconstruction. Typical corrugations of a STMscan have been calculated to be between 0.008-0.013 nm for negative bias voltages while the corrugation varies from0.019-0.024 nmfor positive bias voltages.

Key words: W(100) c(2×2) surface, Zig-zag distortion, STM image

MSC2000: 

  • O641