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采用基于第一性原理的密度泛函理论和平板模型对Si(100)表面吸附乙炔和乙烯分子的构型稳定性以及电子结构进行系统研究.结果表明:无论是吸附乙炔还是乙烯分子,当覆盖度为0.5ML时,最为稳定的吸附方式为dimerized模型;当覆盖度增大到1.0ML时,end-bridge模型为最稳定的吸附方式.通过对各吸附模型的能带结构分析可知,体系的带隙变化可以通过考察表层Si—Si二聚体中Si原子的配位环境来确定.对于相同的吸附模型,无论吸附分子是乙炔还是乙烯,都具有非常相近的带隙.吸附构型以及吸附分子的覆盖度对最小带隙及其来源有较大影响.此外,研究结果还表明,杂化密度泛函方法更适合于描述Si(100)表面的电子结构,尤其是对end-bridge吸附模型.
The structure stability and electronic structure of acetylene and ethylene adsorbed on the surface of Si (100) were systematically studied by using the first-principles-based density functional theory and the flat plate model. The results show that when either acetylene or ethylene is adsorbed, When the degree is 0.5ML, the most stable mode of adsorption is the dimerized model, and the end-bridge model is the most stable mode of adsorption when the coverage is increased to 1.0ML.By analyzing the band structure of each adsorption model, The bandgap variation can be determined by examining the coordination environment of Si atoms in the surface Si-Si dimer.For the same adsorption model, both have similar bandgaps regardless of whether the adsorbed molecules are acetylene or ethylene.Adsorption configurations and adsorption In addition, the results also show that the hybrid density functional method is more suitable for describing the electronic structure of Si (100) surface, especially for the end-bridge adsorption model .