Rangel-Cárdenas Jesús, Sobral Hugo
Centro de Ciencias Aplicadas y Desarrollo Tecnológico, Universidad Nacional Autónoma de México (CCADET-UNAM), Apartado Postal 70-186, Ciudad de México 04510, Mexico.
Materials (Basel). 2017 Jun 1;10(6):607. doi: 10.3390/ma10060607.
In this work, the reflectance, optical absorption, and band gap have been determined for CdTe thin films grown on planar and microstructured substrates. The treated surface was prepared by laser ablation of a silicon wafer, forming holes in a periodic arrangement. Thin films were grown by pulsed laser ablation on silicon samples kept at 200 °C inside a vacuum chamber. The presence of CdTe was verified with X-ray diffraction and Raman spectroscopy indicating a nanocrystalline zinc blended structure. The optical absorption of thin films was calculated by using the Fresnel laws and the experimental reflectance spectrum. Results show that reflectance of 245 nm films deposited on modified substrates is reduced by up to a factor of two than the obtained on unchanged silicon and the optical absorption is 16% higher at ~456 nm. Additionally, it was determined that the band gap energy for planar and microstructured films is about 1.44 eV for both cases.
在本工作中，已测定了在平面和微结构衬底上生长的碲化镉（CdTe）薄膜的反射率、光吸收率和带隙。通过对硅片进行激光烧蚀制备处理后的表面，形成周期性排列的孔洞。在真空室内将硅样品保持在200°C，通过脉冲激光烧蚀生长薄膜。用X射线衍射和拉曼光谱验证了CdTe的存在，表明其为纳米晶闪锌矿结构。利用菲涅耳定律和实验反射光谱计算薄膜的光吸收率。结果表明，沉积在改性衬底上的245nm薄膜的反射率比在未改性硅上获得的反射率降低了多达两倍，并且在约456nm处光吸收率高16%。此外，还确定平面和微结构薄膜的带隙能量在两种情况下均约为1.44eV。
