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中国物理学会期刊

金刚石晶格上的对角无序与非对角无序非晶量子点

CSTR: 32037.14.aps.43.991

SITE-DIAGONAL DISORDER AND OFF-DIAGONAL DISO-RDER AMORPHOUS QUANTUM DOTS ON DIAMOND LATTICE

CSTR: 32037.14.aps.43.991
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  • 报道金刚石晶格上对角无序与非对角无序非晶量子点的理论研究,用简单的紧束缚哈密顿量描述模型的电子结构,用recursion方法求解哈密顿方程,用边界条件对本征值的影响判断局域化,研究发现,带边为扩展态时,带宽的变化趋势与晶态量子点类似;带边为局域态时,尺寸超过某一临界长度后,带宽不变,但带边态密度随尺寸增大而增大。还研究了非晶量子点的介电函数虚部ε2(?ω)。与扩展态对应的ε2(?ω),对尺寸变化较敏感。与局域态对应的ε2(?ω),当尺寸大于

     

    The theoretical studies about site-diagonal disorder and off-diagonal disorder amorphous quantum. dots on diamond lattice are reported. We describe the electronic structures of the amorphous models by simple tight-binding Hamiltonian, solve the Ha-miltonian equation by recursion method, and study the localization behavior from the sensitivity of eigenvalues to a change in boundary conditions. It is found that if the band edges of amorphous quantum dots are consisted of extended states, the changing tendency of the band widths with size are similar to that of crystal quantum dots; if they are consisted of localized states, the band widths do not change with size when the size is greater than a critical one, but the densities of states at the band edges increase with size. The imaginary part of dielectric function ε2(?ω) of amorphous quantum dots is also studied. The ε2(?ω) corresponding to extended state is sensitive to the change of size. The ε2(?ω) corresponding to localized state has a small value and is insensitive to the change of size when the size is greater than localization length Lloc; when the size is close to or less than Lloc; there are no difierences between localized states and extended states, and ε2(?ω) increases quickly with the decrease of size.

     

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