This work is focused on study and optimization of diffusion of Fe in ZnSe from the metal phase, comparative
spectroscopic characterization of kinetic properties of Fe:ZnSe crystals with a wide range of concentrations, and energy
scaling of the Fe:ZnSe gain-switched laser. Iron doping of ZnSe polycrystals was performed by thermal diffusion from
the iron film made by thermal evaporation process. Special cleaning of the ZnSe surfaces and optimization of the ZnSe
substrate temperature and the rate of Fe evaporation resulted in significant enhancement of the diffusion process and
enabled fabrication of high optical density crystals with Fe concentration up to 2x1020 cm-3. The diffusion coefficient and
diffusion length of iron in ZnSe at 1000°C were estimated as 2.1x10-9 cm2/s and 1.3 mm, respectively. We report a
detailed absorption, emission, and kinetics of fluorescence of Fe:ZnSe spectroscopy performed over a broad range of Fe
concentrations (5x1018 - 2x1020 cm-3) and temperatures (14-300K) under direct 2.78μm excitation.
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