透過氫氟酸在適當的偏壓下對矽晶做陽極處理後，其表面會形成
多孔結構。此過程中不僅使矽晶轉變成多孔矽，同時也會產生奈米等
級的矽晶粒。當材料尺寸縮小至奈米尺度時，會出現量子侷限效應，
使得原本不具發光性的矽晶，轉變為具發光特性的多孔矽。而多孔矽
發光特性與孔洞大小相關，孔洞大小的量化可以使用孔隙率表示。
本論文利用影像處理的方法量化孔隙率，接著，針對不同孔隙率
的樣品，分析反射比例、光致發光光譜（PL）與拉曼光譜，探討其光
學性質的變化。最後，將PL光譜的峰值位置代入有效質量近似（EMA）
模型，藉此推估晶粒尺寸。

此外，本論文量測在蝕刻方向上的光學性質變化，藉由PL與拉曼
光譜量測，分析在不同孔隙率下，其光學性質隨深度的變化。
透過上述量測，結果說明當孔隙率逐漸上升時，PL峰值能量逐漸
藍移，對應晶粒尺寸亦隨之減小，同時拉曼峰值會呈現紅移。

When silicon crystals are anodized in hydrofluoric acid under appropriate bias, a porous structure forms on the surface. This process not only transforms crystalline silicon into porous silicon (PS), but also generates silicon nanocrystals. As the material size is reduced to the nanoscale, quantum confinement effects emerge, enabling silicon,which is normally non-luminescent, to exhibit photoluminescent properties. The photoluminescence of porous silicon is closely related to pore size, which can be quantitatively represented by porosity.

In this study, porosity was quantified using image processing techniques. Subsequently, the optical properties—including reflection ratio, photoluminescence (PL), and Raman spectra—were analyzed for samples with different porosities. The peak positions of the PL spectra were used in the effective mass approximation (EMA) model to estimate the nanocrystal sizes.

Additionally, this study investigates the variation of optical properties along the etching depth direction. By measuring PL and Raman spectra at different depths, the relationship between optical characteristics and porosity variation with depth is analyzed.

The results show that as porosity increases, the PL peak exhibits a blue shift, indicating a reduction in nanocrystal size. Simultaneously, the Raman peak shows a red shift.

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