本論文利用高溫熱處理方式，研究高溫下材料交互擴散及孔隙擴 散及對薄膜材料的影響與改變，以及所造成的折射率變化作深入分析， 並依據擴散機制完成非均勻薄膜製作，其中包含Ta2O5/TiO2、 Al2O3/MgO、Al2O3/ZnO 等材料組合，三種材料組合在高溫熱處理下 的擴散現象各有不同，其中Ta2O5/TiO2 組合在800oC 下單純以材料濃 度梯度造成交互擴散現象， 可應用於漸變折射率膜層設計。 Al2O3/MgO 組合在800oC 下兩材料會進行交互擴散，並在介面生成二 次相MgAl2O4，同時在擴散速率較快的MgO 層產生微小孔洞，孔洞 生成降低MgO 膜層等效折射率，而Mg 原子擴散至Al2O3 膜層中形 成MgAl2O4 則提高原Al2O3 層折射率，使高低折射率差異由原本0.11 增大為0.14135，約增大28.5 %。利用此現象製做(Al2O3 MgO)8 Al2O3 多層膜經800oC、4 小時熱處理可得到(MgAl2O4 MgO+voids)8 MgAl2O4 之膜層結構，因熱處理後使得高低折射率材料位置互換，以及高低折 射率材料差異擴大，故可得到反射率約61%之反射濾光片，並與模擬 數值一致。Al2O3/ZnO 材料組合在800oC 下ZnO 與Al2O3 介面生成二 次相ZnAl2O4，孔洞大量生成於ZnO 層，降低ZnO 折射率，完全反 應後ZnO 層中孔隙率達58.6 %，折射率降為1.357。;In this study, the influence of solid state diffusion on refractive index of thin films had been studied using thermal annealing method at high temperature. Base on solid state diffusion mechanism, we prepared three different material pairs, including Ta2O5/TiO2, Al2O3/MgO, Al2O3/ZnO. Each of these material pairs represented a different diffusion situation. Only interdiffusion phenomenon appeared at the interface of Ta2O5 and TiO2 at annealing temperature of 800oC and made the graded refractive index layer. According to the concept, we could design the rugate filter employed the suitable material pair. In Al2O3/MgO case, MgAl2O4 spinel layer growth between MgO and Al2O3 during annealing process of 800oC. Besides, some voids developed in the MgO layer and the apparent refractive index of MgO layer was decreased. The voids were caused by the faster diffusion rate of MgO than Al2O3 and increased the refractive index difference of 28.5% between high and low refractive index materials in the multilayer. Base on the reaction mechanism of Al2O3 and MgO, (Al2O3 MgO)8 Al2O3 multilayer would become (MgAl2O4 MgO+voids)8 MgAl2O4 after annealing process of 800oC for 4 hours. After annealing process, the positions of high and low refractive index materials exchanged, and the effective refractive indices of MgO layers were decreased due to the presence of voids. Beside, the refractive index difference of the multilayer was increased by 28%. Therefore, the reflective filter with 61% reflection at 300nm was obtained. The same as Al2O3/MgO pair, ZnAl2O4 spinel layer growth between ZnO and Al2O3 during annealing process of 800oC. A lot of voids developed in ZnO layer and caused much decrease in refractive index. The porosity of ZnO layer after annealing process achieves 58.6 % and the refractive index decreased to 1.357 at 550 nm wavelength.
