Phosphine dissociation and diffusion on Si(001) observed at the atomic scale
Phosphine dissociation and diffusion on Si(001) observed at the atomic scale
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DOI：
10.1021/jp054646v
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发表时间：
2006-02-23
影响因子：
3.3
通讯作者：
Clark, RG
中科院分区：
文献类型：
--
作者：
Schofield, SR;Curson, NJ;Clark, RG
采用原子分辨扫描隧道显微镜（STM）和密度泛函理论（DFT）研究了磷化氢（PH3）在Si（001）上的吸附、解离和表面扩散.研究了吸附剂从0.01单层到饱和的覆盖率，并在室温和120 K下进行吸附。结果表明，在室温下，当吸附到Si（001）上时，PH 3解离产生PH 2 + H和PH 2 + H。这些出现在原子分辨率STM图像的功能不对称的二聚体行，分别约和中心。PH 2与PH的比率是剂量率和温度的函数，并且在室温下PH 2解离成PH在分钟的时间尺度上发生。这些吸附物的时间分辨的STM原位观察显示的表面扩散的PH 2吸附物（介导的孤对电子）和PH 2的解离为PH。PH 2的表面扩散的结果在低剂量的Si（001）表面和PH分子的有序沿着二聚体行在饱和覆盖率的形成半氢化物二聚体。这里提出的意见有重要的影响，原子级的P掺杂剂结构在Si中的制造，和方法是适用于其他新兴领域的纳米技术，如分子电子学，其中明确的分子识别使用STM是必要的。
A detailed atomic-resolution scanning tunneling microscopy (STM) and density functional theory study of the adsorption, dissociation, and surface diffusion of phosphine (PH3) on Si(001) is presented. Adsorbate coverages from similar to 0.01 monolayer to saturation are investigated, and adsorption is performed at room temperature and 120 K. It is shown that PH3 dissociates upon adsorption to Si(001) at room temperature to produce both PH2 + H and PH + 2H. These appear in atomic-resolution STM images as features asymmetric-about and centered-upon the dimer rows, respectively. The ratio of PH2 to PH is a function of both dose rate and temperature, and the dissociation of PH2 to PH occurs on a time scale of minutes at room temperature. Time-resolved in situ STM observations of these adsorbates show the surface diffusion of PH2 adsorbates (mediated by its lone pair electrons) and the dissociation of PH2 to PH. The surface diffusion of PH2 results in the formation of hemihydride dimers on low-dosed Si(001) surfaces and the ordering of PH molecules along dimer rows at saturation coverages. The observations presented here have important implications for the fabrication of atomic-scale P dopant structures in Si, and the methodology is applicable to other emerging areas of nanotechnology, such as molecular electronics, where unambiguous molecular identification using STM is necessary.