Magneto-optical properties of wider gap II-VI ZnMnTe and ZnMnCoTe films

In CdMnTe and CdMnCoTe films, Mn shifts the absorption edge toward higher energies. However, this gap shift occurs at around $2.1eV$ because the band gap of the combination of CdTe $(1.53eV)$ and wideband gap MnTe $(2.9eV)$ is small. In order to widen the gap of $AII1−xMnxBVI$ alloys and effectively use LDs that work at shorter wavelengths for Faraday rotation, we have studied ZnMnTe and ZnMnCoTe films, whose parent materials are wideband gap ZnTe $(2.28eV)$ and MnTe. The relationship between the quantity $(αhν)2$ and the optical energy for $Cd0.65Mn0.35Te$ and data on $Zn0.75Mn0.25Te$ and $Zn0.79Mn0.20Co0.01Te$ films showed that the direct gap energy of the $Cd0.65Mn0.35Te$ film is roughly $2.25eV$ and the gap of $Zn0.75Mn0.25Te$ and $Zn0.79Mn0.20Co0.01Te$ $(∼2.4eV)$ is $0.15eV$ $(∼40nm)$ larger than that of $Cd0.65Mn0.35Te$⁠. The increase is due to the combination of wideband gap ZnTe and MnTe. Transparency and Faraday rotation are observed for $Zn1−xMnxTe$ and $Zn1−x−yMnxCoyTe$ films.