紫外波段SiO2/Si3N4介质膜分布式布拉格反射镜的制备与研究

采用光学传递矩阵方法设计了紫外波段SiO₂/Si₃N₄介质膜分布式布拉格反射镜, 并利用等离子体增强化学气相沉积技术在蓝宝石(0001)衬底上制备了SiO₂/Si₃N₄介质膜分布式布拉格反射镜. 光反射测试表明, 样品反射谱的峰值波长仅与理论模拟谱线相差10 nm, 并随着反射镜周期数的增加而蓝移. 由于SiO₂与Si₃N₄具有相对较大的折射率比, 因而制备的周期数为13的样品反射谱的峰值反射率就已大于99%. 样品反射谱的中心波长为333 nm, 谱峰的半高宽为58 nm. 样品截面的扫描电子显微镜和表面的原子力显微镜测量结果表明, 样品反射谱的中心波长蓝移是由子层的层厚和界面粗糙度的变化引起的. X射线反射谱表明,子层界面过渡层对于反射率的影响较小, 并且SiO₂膜的质量比Si₃N₄差, 也是造成反射率低于理论值的原因之一.

Design and fabrication of SiO2/Si3N4 dielectric distributed Bragg reflectors for ultraviolet optoelectronic applications

In this paper,we design a SiO₂/Si₃N₄ dielectric distributed Bragg reflector（DDBR） by the transfer-matrix method,which is grown by plasma-enhanced chemical vapor deposition on sapphire（0001）.There exists a slight difference between theoretical and experimental results in peak wavelength（¹0 nm）.The peak wavelength is blue shifted with the number of DDBR pairs increasing. The 13-pair DDBR provides a 58 nm wide stop band centered at 333 nm with a maximal reflectivity of higher than 99%,as the refractive index ratio of Si₃N₄ to SiO₂ is relatively high.It is proved by the scanning electron microscope and atomic force microscope measurements that the variations of thickness and roughness of Si₃N₄ layer with respect to SiC>2 layer during growth contribute to the blue shift of peak wavelength.The X-ray reflectivity measurements indicate that the interfacial degradation of the samples has little effect on the maximum reflectivity,and the relatively poor quality of SiO₂ compared with Si₃N₄ may be one of the reasons that cause the difference between the measurements and simulations.