Annealing Influence on Structural and Luminescencent Properties of ZnSe:Fe

Zinc Selenide crystals doped with Iron are promising material to be used as an active media in tunable mid-IR lasers (4 - 5 μ m) [1]. The ZnSe:Fe lasing characteristics close to the theatrical maximum are obtained by optical excitation [2]. Nowadays other pumping methods are also being explored. Previously we have observed luminescence in the mid-IR spectral region with the maximum at the wavelength of 3.9 μ m under electron-impact excitation. The present research is focused on the influence of annealing process in Zn atmosphere on defective-impurity compound (DIC) and intensity of mid-IR cathodoluminescence (CL). We studied DIC by two-photon confocal microscopy (TPCM) on Carl Zeiss LSM NLO 710 (commercially available equipment). The TPCM allows detecting edge luminescence (EL) (460-480 nm) and DIC (480-725 nm) as well as mapping luminescence distribution [3]. In the CL experiments, the crystals were excited by a pulsed electron gun with the accelerated electron energy of 36 kV [4]. A series of ZnSe single crystals doped with Fe by thermal diffusion from surface was subjected to the DIC and CL studies. The initial ZnSe plates were cut from boules grown from the melt by the Bridgman method with an addition of Tellurium. Iron concentrations varied from 0.01 to 14 wt.% as determined by XDR. The samples were observed by TPCM and CL before and after annealing in Zn atmosphere.