CdSiP_2晶体退火及对红外光学性能的影响

Effect of Annealing on Infrared Optical Properties of CdSiP_2 Crystal

采用改进的布里奇曼法生长出Cd Si P_2单晶体,运用X射线能谱仪、傅里叶变换红外分光光度计以及红外显微镜等对在不同气氛中退火前后的Cd Si P_2晶体进行了组分元素、红外吸收系数以及红外透过均匀性测试,根据红外显微镜Mapping图像的标准差值评判了晶体的红外透过均匀性。研究结果表明,经真空、Cd Si P_2粉末包裹、P/Cd（原子比为2：1）、Cd气氛等退火后,晶体组分元素的化学计量比、红外吸收系数和红外光学均匀性都得到了不同程度的改善,其中在1.29～2.00μm,经Cd Si P_2粉末包裹退火后的晶体吸收系数改善显著,在1.92～1.98μm波段的红外透过均匀性提高了14.06%;而在Cd气氛下退火后晶体的吸收系数在2.00～6.50μm波段降低最为明显,在2.70～2.78μm波段红外透过均匀性提高了17.43%。分析讨论了在上述波段中引起晶体红外吸收和红外透过不均匀性的主要因素,研究出较为有效的Cd Si P_2晶体退火工艺。

A CdSiP2 （CSP） crystal was grown by the modified Vertical Bridgman method. Four wafers which were cut from the crystal with the [001] direction and annealed under four different atmospheres, i. e. vacuum, cover-up with CSP polycrystalline powder, P/Cd （atomic ratio of 2：1） and Cd atmosphere. Then, Energy Disperse X-ray Spectroscopy, Fourier Transform Infrared Spectrophotometer and the Mapping System of Infrared Microscope were employed to analyze the properties of the CdSiP2 wafers before and after annealing, including the elementary composition, infrared absorption coefficients and infrared transmission uniformity. The measurement results show that all the stoichiometric deviation and infrared absorption coefficients are reduced, and infrared transmission uniformity of CSP wafers are improved to different extent after annealing. For the infrared absorption coefficients in the range of 1.29-2.00 μm, the most obvious decrease is due to annealing under cover-up with CSP polycrystalline powder. Meanwhile, the wafer treaded by this method also obtained the best result for infrared transmission uniformity in 1.92-1.98 μm with the increase of 14.06%. The wafer annealed under the Cd atmosphere has the lowest infrared absorption coefficients in 2.00-6.50 μm among the four wafers, and has the most obvious improvement for the infrared transmission uniformity in 2.70-2.78 μm with the increase of 17.43%. The main factors resulting in nonuniformity absorption in the wavebands mentioned above and corresponding effective annealing processes will analyze in this work.