Size-Dependent Optical Properties of Zinc Blende Cadmium Telluride Quantum Dots

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• 作者：John Sundar Kamal ; Abdoulghafar Omari ; Karen Van Hoecke ; Qiang Zhao ; Andr茅 Vantomme ; Frank Vanhaecke ; Richard Karel Capek ; Zeger Hens
• 刊名：The Journal of Physical Chemistry C
• 出版年：2012
• 出版时间：March 1, 2012
• 年：2012
• 卷：116
• 期：8
• 页码：5049-5054
• 全文大小：323K
• 年卷期：v.116,no.8(March 1, 2012)
• ISSN：1932-7455

文摘

We analyze the optical properties of CdTe quantum dots, including the sizing curve, the absorption coefficient, and the oscillator strength of the band gap transition, by combining absorption spectroscopy, elemental analysis, and electron microscopy imaging. At short wavelengths, the absorption coefficient spectrum is still affected by quantum confinement, yet a largely constant value, close to that of bulk CdTe, is found at around 410 nm. At shorter wavelengths, remaining quantum confinement effects on the CdTe E₁ transition are present even for the largest quantum dots studied (11 nm). For the band gap transition, we find an integrated absorption coefficient 渭_gap that scales almost proportionally to the inverse of the quantum dot volume. Especially for the smaller diameters, deviations up to a factor of 3 are found as compared to widely used literature values. The corresponding oscillator strength f_gap is almost size-independent in the diameter range 3鈥? nm. The correspondence between radiative lifetimes predicted based on f_gap and literature values is discussed.