Dependence of indices of refraction on Mn composition of Zn1−xMnxSe thin films using prism coupler technique
We have measured the dependence of the indices of refraction n on alloy composition x of Zn1−xMnxSe films grown by MBE on GaAs (100) substrates for a series of alloy compositions x. The Mn compositions of the films were determined by XRD. A prism coupler technique was used to measure n and thickness of each of the alloy films. On the whole, the indices of refraction nobtained by this method decrease linearly as increasing x showing an inverse relationship with respect to their band gaps, in spite of showing a minimum in the near-band gap energy in the region of 0 ≤ x ≤ 0.1. We obtained a linear calibration function for n as from the prism coupler technique, which can be used to make an accurate estimate the Mn composition in the Zn1−xMnxSe alloy system if you only measure n. And, the crystalline quality of the Zn1−xMnxSe alloy film was deteriorated showing an exponential dependence of FWHM ratio of alloy layer to GaAs substrate obtained from DCRC as increasing Mn mole fraction.
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