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使用基于密度泛函微扰理论的线性响应方法,模拟研究了强激光辐照对闪锌矿结构的碳化硅晶体结构稳定性的影响.通过计算在不同电子温度下3C-SiC晶体的声子色散曲线,发现3C-SiC的横声学声子频率随电子温度的升高会出现虚频,其临界电子温度是3.395 eV.结果表明,在强激光辐照下3C-SiC晶体变得不稳定,这与以前对金刚石结构的碳、硅和闪锌矿结构的砷化镓、锑化铟的研究结果非常类似.电子温度在0—4.50 eV范围内时,3C-SiC晶体在Γ点的LO-TO分裂度随电子温度的升高而增大,超过4.50 eV后随电子温度的升高而减小.这表明只有在足够强的激光辐照下,电子激发才会削弱晶体的离子性强度.
The influence of intense laser irradiation on the stability of the silicon carbide crystal structure of sphalerite was simulated by using the linear response method based on the theory of density functional perturbation. By calculating the phonon dispersion of 3C-SiC crystal at different electron temperature Curve and found that the 3C-SiC transverse acoustic phonon frequency with the rise of electron temperature will appear imaginary frequency, the critical electron temperature is 3.395 eV.The results show that 3C-SiC crystals become unstable under intense laser irradiation, which Similar to the previous studies on gallium arsenide and indium antimonide for diamond-structured carbon, silicon and sphalerite structures, the LO-TO of 3C-SiC crystals at the Γ point at electron temperatures from 0 to 4.50 eV The degree of splitting increases with the increase of the electron temperature, and decreases with the increase of the electron temperature beyond 4.50 eV, indicating that the electron excitation weakens the ionic strength of the crystal only under sufficiently intense laser irradiation.