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摘要: 采用经验紧束缚理论,以类似闪锌矿结构的晶体模型模拟GexSi1-x合金,根据总能最小原则计算了GexSi1-x合金中的键长及点阵常数.同时以紧束缚方法计算了原子位置发生弛豫前后的电子能带结构,并与虚晶近似下的计算结果进行了比较.计算结果表明,GexSi1-x合金中的键长基本上与合金组分无关,各自接近于Ge,Si晶体中的键长,与广延x射线吸收精细结构(EXAFS)测量结果符合得
Abstract: Using the empirical tight-binding method, the bond lengths and lattice constants in the GexSi1-x alloys are calculated through minimizing the total energy in zincb-lend-like crystal models, with which the GexSi1-x alloys are simulated. With the tight-binding method the electronic band structures are calculated for the models before and after the atoms relax and the calculated results are compared with that obtained in virtual crystal approximation. The calculated results are as follows: The bond lengths in the GexSi1-x alloys generally do not depend up on the alloy compo-sition and nearly equal to the bond lengths in the Ge and Si crystals respectively. This result is consistent with the experiments quite well. The relaxation of atoms has little effects on the electronic band structures for the alloys. However, the chemical composition disorder plays the most important role in determining them.