有效介质近似在Cu-MgF_2复合纳米颗粒薄膜光学性质中的适用性研究  

Study on Applicability of Effective Medium Approximation to Optical Properties of Cu-MgF_2 Composite Nanoparticle Films

作　　者：王佩红[1] 戴旭涵[1] 赵小林[1] 宋学萍[2] 孙兆奇[2] 

机构地区：[1]上海交通大学微米/纳米加工技术国家级重点实验室薄膜与微细技术教育部重点实验室,上海200030 [2]安徽大学安徽省信息材料与器件重点实验室,合肥230039

出　　处：《光学学报》2006年第12期1871-1876,共6页Acta Optica Sinica

基　　金：国家自然科学基金(59972001);安徽省自然科学基金(01044901);安徽省人才专项基金(2004Z029);安徽省信息材料与器件重点实验室开放课题基金资助课题

摘　　要：采用射频磁控共溅射技术制备了Cu体积分数分别为15％和30％的Cu—MgF2复合纳米颗粒薄膜。透射电镜形貌图像表明，薄膜由不同形状的Cu晶态纳米微粒镶嵌于主要为非晶态的MgF2陶瓷基体中构成。用椭偏光谱技术计算得到Cu—MgF2复合薄膜在270-830nm波段的光学常数谱。用考虑颗粒形状效应的有效介质近似计算得到Cu—MgF2复合薄膜在相同波段的光学常数谱。谱相结合，分析讨论了Cu—MgF2复合薄膜的光学特性。把两样品的透射电镜形貌图像与光学常数理论谱、实验结果表明：去极化因子取值0．33的麦克斯韦-噶尼特（Maxwell-Garnett）模型可以较好地解释Cu体积分数为15％的Cu—MgF2复合薄膜的光学性质，而去极化因子取值0．6的布鲁格曼（Bruggeman）模型可以较好地解释Cu体积分数为30％的Cu—MgF2复合薄膜的光学性质。Cu-MgF2 composite nanoparticle films with the copper volume fraction of 15% and 30% were prepared by radio-frequency magnetron co-sputtering technique. The transmission electron microscopy （TEM） images of Cu-MgF2 composite films show that the films are mainly made of amorphous ceramic MgF2 matrix with embedded Cu nanoparticles with various grain shapes. The optical constants spectra of the composite films are determined as a function of wavelength in the range of 270-830 nm by spectroscopic ellipsometry. The theoretical optical constants spectra of the composite films are calculated in the same wavelength range by effective medium approximation in which grain shape effect is incorporated. The optical properties of the two composite films are analyzed and discussed by combining TEM images with experimental and theoretical optical constants spectra. The conclusion is drawn that Maxwell-Garnett model in which the depolarization factor of Cu grains is o. 33 is suitable to explain the optical properties of 15 % Cu-MgF2 film, and the optical properties of 30 % Cu-MgF2 film may be better interpreted with the depolarization factor of Cu grains 0. 6.

关 键 词：薄膜光学 光学性质 Cu—MgF2复合纳米颗粒薄膜 有效介质近似 光学常数 

分 类 号：O484[理学—固体物理]