Birefringence and band structure of CdP₂ crystals

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• 作者：S.I. Beril^a ; I.G. Stamov^a ; N.N. Syrbu^b ; ^{sirbunn@yahoo.com} ; V.V. Zalamai^c
• 关键词：Semiconductor compound ; Optical absorption and reflection spectra ; Kramers&ndash ; Kronig relations ; Optical constants ; Excitons ; Band structure
• 刊名：Physica B
• 出版年：2013
• 出版时间：1 August, 2013
• 年：2013
• 卷：422
• 期：Complete
• 页码：12-19
• 全文大小：2728 K

文摘

The spatial dispersion in CdP₂ crystals was investigated. The dispersion is positive (n^k||§ã>n^k||§å) at ¦Ë>¦Ë₀ and negative (n^k||§ã<n^k||§å) at ¦Ë<¦Ë₀. CdP₂ crystals are isotropic for wavelength ¦Ë_§à=896 nm. Indirect transitions in excitonic region §¦_gx are nonpolarized due to one pair of bands. Minimal direct energy intervals correspond to transitions §¤₁¡ú§¤₁ for §¦^||§ã and §¤₂¡ú§¤₁ for §¦¡Í§ã. The temperature coefficient of energy gap sifting in the case of temperature changing between 2 and 4.2 K equals to 10.6 meV/K and 3.2 mev/K for §¤₁¡ú§¤₁ and §¤₂¡ú§¤₁ band gap correspondingly. Reflectivity spectra were measured for energy interval 1.5-10 eV and optical functions (n, k, ¦Å₁, ¦Å_2, d²¦Å₁/dE² and d²¦Å₂/dE²) were calculated by using Kramers-Kronig analyses. All features were interpreted as optical transitions on the basis of both theoretical calculations of band structure.