Nonlinear optical investigations of the dynamics of hydrogen interaction with silicon surfaces
Nonlinear optical investigations of the dynamics of hydrogen interaction with silicon surfaces
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氢与硅表面相互作用动力学的非线性光学研究
DOI：
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发表时间：
1996
期刊：
影响因子：
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通讯作者：
U. Höfer
中科院分区：
文献类型：
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作者：
U. Höfer
硅表面的光学二次谐波产生（SHG）可以通过悬挂键衍生的表面态共振增强。由此产生的对氢吸附的高灵敏度与二次谐波作为光学探针的独特特征相结合，已被用来研究吸附系统 H2/Si 的各个动力学和动力学方面。对 H/Si(111)7×7 表面扩散以及 Si(111)7 × 7 和 Si(100)2 × 1 中氢的复合解吸的研究表明，硅表面氢键的共价性质导致高扩散势垒和强烈依赖于表面结构的解吸动力学。最近，通过将表面加热至 550 K 至 1050 K 之间的温度并监测暴露于高通量 H2 或 D2 期间的 SH 响应，首次观察到分子氢在 Si(100)2×1 和 Si(111)7×7 上的解离吸附。测量的气体温度为 300K 时的初始粘附系数范围为 10−9 至 10−5，并且随着表面温度的变化而急剧增加。这些结果表明晶格自由度可能在半导体表面的反应动力学中发挥决定性作用。
Optical second-harmonic generation (SHG) from silicon surfaces may be resonantly enhanced by dangling-bond-derived surface states. The resulting high sensitivity to hydrogen adsorption combined with unique features of SHG as an optical probe has been exploited to study various kinetical and dynamical aspects of the adsorption system H2/Si. Studies of surface diffusion of H/Si(111)7×7 and recombinative desorption of hydrogen from Si(111)7 × 7 and Si(100)2 × 1 revealed that the covalent nature of hydrogen bonding on silicon surfaces leads to high diffusion barriers and to desorption kinetics that strongly depend on the surface structure. Recently, dissociative adsorption of molecular hydrogen on Si(100)2×1 and Si(111)7×7 could be observed for the first time by heating the surfaces to temperatures between 550 K and 1050 K and monitoring the SH response during exposure to a high flux of H2 or D2. The measured initial sticking coefficients for a gas temperature of 300K range from 10−9 to 10−5 and strongly increase as a function of surface temperature. These results demonstrate that the lattice degrees of freedom may play a decisive role in the reaction dynamics on semiconductor surfaces.