The Fe²⁺:ZnSe crystal is an important material for 3–5 μm mid-infrared lasers. In this work, we have grown different doping concentrations of Fe²⁺:ZnSe and Fe²⁺, Cr²⁺:ZnSe by the chemical vapor transport method. The doped crystals have the same structure. The lattice constant increases slightly with a higher Fe²⁺ concentration, while the doped Cr²⁺ has a great influence on the lattice constant. Besides, with a higher Fe²⁺ concentration, the TO mode has no change and the LO mode presents a small blue shift. The doped ZnSe crystals all have a wide absorption peak in the range of 2.3–4.5 μm, and these absorption peaks widen with the increase of the Fe²⁺ doping concentration. Besides, in the range of 5–20 μm, the crystals have good transparency. The concentrations of 3, 2, and 1% Fe²⁺ samples are calculated to be 4.15 × 10¹⁹, 3.27 × 10¹⁹, and 3.02 × 10¹⁹ cm^–3, respectively, and the Fe²⁺ concentration of the Fe²⁺, Cr²⁺:ZnSe sample is 3.71 × 10¹⁹ cm^–3. The band gap decreases from 2.52 to 2.27 eV with a higher Fe²⁺ doping concentration. Therefore, we can modulate the absorption bandwidth and band gap by doping the ion concentration, which is more suitable for developing mid-infrared gain medium applications.

中文翻译：

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不同掺杂浓度对化学气相传输法生长的Fe2+：ZnSe和Fe2+、Cr2+：ZnSe晶体性能的影响


Fe²⁺：ZnSe 晶体是 3-5 μm 中红外激光器的重要材料。在这项工作中，我们通过化学气相传输法生长了不同浓度的 Fe²⁺：ZnSe 和 Fe²⁺、Cr²⁺：ZnSe。掺杂晶体具有相同的结构。晶格常数随着 Fe²⁺ 浓度的升高而略有增加，而掺杂的 Cr²⁺ 对晶格常数的影响很大。此外，随着 Fe²⁺ 浓度的升高，TO 模式没有变化，LO 模式呈现一个小的蓝移。掺杂的 ZnSe 晶体在 2.3–4.5 μm 范围内都具有较宽的吸收峰，并且这些吸收峰随着 Fe²⁺ 掺杂浓度的增加而扩大。此外，在 5-20 μm 的范围内，晶体具有良好的透明度。计算出 3、2 和 1% Fe²⁺ 样品的浓度分别为 4.15 × 10¹⁹、3.27 × 10¹⁹ 和 3.02 ×10¹⁹ cm^{–3，Fe 2+}、Cr²⁺：ZnSe 样品的 Fe²⁺ 浓度为 3.71 ×^{10 19} cm^–3。带隙从 2.52 eV 降低到 2.27 eV，Fe²⁺ 掺杂浓度越高。因此，我们可以通过掺杂离子浓度来调制吸收带宽和带隙，这更适合开发中红外增益介质应用。