近紅外單光子崩潰二極體 (Single Photon Avalanche Photodiode, SPAD)的應用相當廣泛，包含生物螢光分析、電子產業的VLSI 電路、 軍事、商業上的量子加密和車用電子偵測系統等。其操作原理是利用 元件逆向偏壓於崩潰電壓之上，理論而言吸收單光子便能觸發衝擊游 離機制，產生無窮大之增益，因此能夠偵測極弱的光。 為了提高動態偵測範圍 (dynamic range)或實現成像相關之應用， 可將SPAD 元件製作成多像素陣列；陣列的設計目標是縮小SPAD 元 件之間的距離以提高偵測效率，減少光子損失。然而當元件間距微縮 時，因元件崩潰時產生的breakdown flash 將影響相鄰元件的操作，導 致鄰近元件發生不預期之崩潰，換言之，元件間距縮小將使光學串擾 的現象越趨嚴重；在此論文中，我們使用光學模擬軟體Rsoft 的 Fullwave 功能，將計算共振腔品質因子的方法延伸到模擬SPAD 元件 中的光學串擾，計算二維陣列中breakdown flash 傳遞至相鄰元件的能 量密度，並藉此方法計算在不同元件間距、金屬溝槽隔離、隔離深度 條件下，breakdown flash 對相鄰元件的影響，結果顯示能量密度與預 期趨勢相同，印證我們提出的方法可延伸模擬SPAD 陣列光學串擾之 現象。我們亦進一步討論共振腔結構對陣列中光學串擾的影響。;Near infrared single photon avalanche diodes (SPAD) have many applications in various field, such as fluorescence lifetime imaging microscopy in life sciences, VLSI circuits in electronics industries, military and commercial quantum encryption, and automotive electronic detection systems. A SPAD is reversely biased above the breakdown voltage and the absorption of single photon can trigger impact ionization process, resulting infinite number of carriers. Therefore, it is capable of detecting faint light. In order to improve the dynamic range as well as to perform the imaging applications, a multi-pixel SPAD array is required. The array size and density increases for improving photon detection efficiency and reducing the losses of incoming photons. However, as the distance between each pixel is reduced, the breakdown flash generated by the avalanche carriers will couple to nearby SPADs in the array and induce unwanted avalanche events. In other words, the optical crosstalk will become more serious as shrinking the spacing between pixels. In this thesis, we use the simulation tool of Fullwave in Rsoft to study the optical crosstalk in SPADs by applying the method that is used to calculated the quality factor of an optical cavity. Based on the above method, we can calculate the energy density of breakdown flash propagation in a 2D array. The optical crosstalk can be well predicted under different conditions of pixel spacing, metal coated trench, and trench depth. We further discuss the optical crosstalk in the resonant cavity-enhanced SPAD structure.
