Growth and luminescence study of Cr2+: ZnSe films deposited by radio-frequency magnetron co-sputtering

The Cr
²⁺
:ZnSe films were deposited on glass, Si or GaAs substrates at room temperature (RT) by radio-frequency magnetron sputtering of a SiO
₂
target covered by ZnSe and Cr chips under argon pressure. The thickness of the films, determined by optical transmission measurements, is found in the range 3-45 mum. Raman spectroscopy and X-ray diffraction investigations reveal that the films are mainly constituted of pure cubic ZnSe, with a strong texture along the [111] direction. The photoluminescence (PL) properties of the films were investigated at different temperatures under direct excitation into the
⁵
T
₂
rarr
⁵
E intracenter absorption band of the Cr
²⁺
ions (1750 nm) using a home made Tm
³⁺
:KY
₃
F laser (1850 nm). The PL spectra at 10K of a reference bulk crystal and a Cr
²⁺
:ZnSe film are measured. They exhibit a large emission band centred at 2200 nm, attributed to intrashell
⁵
T
₂
rarr
⁵
E transition of the Cr
₂₊
ions.