Atomic‐Scale Elucidation of the Anisotropic Etching of (110) n‐Si in Aqueous NH 4 F : Studies by In Situ Scanning Tunneling Microscopy
Atomic‐Scale Elucidation of the Anisotropic Etching of (110) n‐Si in Aqueous NH 4 F : Studies by In Situ Scanning Tunneling Microscopy
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NH 4 F 水溶液中 (110) n-Si 各向异性蚀刻的原子尺度阐明：原位扫描隧道显微镜研究
DOI：
10.1149/1.1837329
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发表时间：
1996
期刊：
影响因子：
--
通讯作者：
K. Itaya
中科院分区：
文献类型：
--
作者：
J. Ye;K. Kaji;K. Itaya
用原位原子分辨扫描隧道显微镜首次研究了NH 4F水溶液中（110）n-Si表面的电化学腐蚀。结果发现，界面秩序的程度是深刻地依赖于所施加的电位。当电位接近开路电位或为开路电位正值时，发生点蚀，导致表面无序。在开路电位的负电位下，发生高度各向异性的逐层溶解，使得粗糙表面原子级平坦。扫描隧道显微镜图像清楚地显示了界面结构，其特征在于沿沿着的锯齿形链。Z字形链上每隔一个Si原子之间的距离被测量为3.8，而链周期被确定为5.4。这些值用于确定受控的负电位蚀刻导致形成理想的H-封端的（110）Si：H -（1 × 1）结构。时间依赖性扫描隧道显微镜被用来深入了解二氢化物Si原子在各向异性蚀刻过程中的作用。高分辨率图像允许通过每单位时间溶解的Si原子的精确数值计数来评估沿着方向的绝对蚀刻速率
The electrochemical etching of (110) n-Si surfaces in aqueous NH 4 F has been studied for the first time by in situ atomic resolution scanning tunneling microscopy. It was found that the degree of interfacial order was profoundly dependent upon applied potential. At potentials near or positive of the open-circuit potential, pit corrosion occurred that resulted in disordered surfaces. At potentials negative of the open-circuit potential, highly anisotropic layer-by-layer dissolution took place that rendered a rough surface atomically flat. The scanning tunneling microscopy images clearly showed an interfacial structure characterized by zigzag chains along the direction. The distance between every other Si atom on the zigzag chain was measured to be 3.8 A, while the chain periodicity was determined to be 5.4 A. These values serve to establish that controlled negative-potential etching resulted in the formation of an ideal H-terminated (110) Si:H - (1 x 1) structure. Time-dependent scanning tunneling microscopy was employed to gain insight into the role of dihydride Si atoms in the anisotropic etching process. High-resolution images allowed the evaluation of absolute etching rates along the direction through an exact numerical count of the Si atoms dissolved per unit time