通过提高生长温度改善碳化锗薄膜的性能

Performance Improvement of Germanium Carbide Films by Increasing Growth Temperature

利用磁控溅射制备碳化锗(Ge1-xCx)薄膜,系统地研究了生长温度(Tg)对所获薄膜成分及性能的影响并揭示了它们之间的内在关系。研究发现所有Ge1-xCx薄膜样品均为非晶结构,随着Tg从60℃增加到500℃,膜中锗含量增加,而碳含量相对降低,这种成分的改变增加了膜中组成原子的平均质量,进而导致薄膜折射率从2.3增加到4.3,这种折射率大范围连续可调的特性十分有利于Ge1-xCx多层红外增透保护膜的设计和制备。此外研究还发现,随着Tg的增加,Ge1-xCx膜中Ge—H和C—H键逐渐减少,这不但显著减小了薄膜在～5.3μm和～3.4μm处的光吸收,而且显著提高了薄膜的硬度。这些结果表明,提高生长温度是调制Ge1-xCx薄膜成分、改善其光学和力学性能的有效途径。

Germanium carbide（Ge1-xCx）films have numerous attractive properties,which make them promising candidates for applications in the field of multilayer antireflection and protection coating of IR window.Although many investigations on the Ge1-xCx films prepared by different deposition techniques have been performed,it is still difficult to summarize from the literature and thus to understand the relationships between the growth process and the film properties.Effects of experimental parameters such as growth temperature on the composition and properties of Ge1-xCx films deposited by reactive magnetron sputtering are not well explored.In this work,the effects of growth temperature（Tg）on the composition,optical and mechanical properties for Ge1-xCx films,prepared via reactive magnetron sputtering,have been investigated.It is found that Ts remarkably influences the film composition,which results in a pronounced change in the refractive index,optical gap and hardness of the film.As Tg increases from 60 ℃ to 500 ℃,the content of carbon and hydrogen in the film decreases,which leads to a significant increase in the refractive index from 2.3 to 4.3 and an accompanying decrease in the optical gap from 1.4 eV to 1.0 eV.Furthermore,with increa-sing Tg the fraction of C—H and Ge—H bonds in Ge1-xCx film decreases,which significantly decreases optical absorption at 5.3 μm and 3.4 μm,and at the same time enhances the hardness of the film.These results suggest that growth temperature is one of key parameters for preparing Ge1-xCx films with excellent performance.