矽雪崩光電二極體特性之模擬研究

Abstract

本文詳細研究了單光子雪崩二極體(SPAD)和與微型環狀共振腔整合的全矽雪崩光電二極體(APD)（第二章），專為通訊頻段應用而設計。此雪崩光電二極體在共振時表現出與其他光電二極體相當的峰值響應，此歸功於高光強度和顯著的摻雜。這導致顯著的熱光非線性和寬頻檢測。初步的模擬結果顯示暗電流低於0.1nA 納安培，電壓高達2V伏特，顯示缺陷極少且絕緣良好。在2V伏特電壓下，觀察到碰撞電離的開始，導致在7V電壓下擊穿，並且由於電子倍增而導致電流快速上升。受體和施體密度強烈影響電場分佈和崩潰電壓，受體和施體密度越高，空乏層會越窄，電場強度也會越高。在零偏壓（平衡狀態）下，單光子雪崩二極體的能帶圖顯示pn接面處有些微的能帶彎曲。當施加5伏特的反向偏壓時，空乏層會變寬，從而增強了電子電洞的分離。在10V時，增強的電場會導致撞擊載子離子化。在15V電壓下，電場保持連續雪崩倍增，且光電流顯著增加。載子密度對電場分佈有重要影響：較高的施體密度會縮小空乏層並增加給定電壓下的電場。較高的施體密度也會縮小空乏層，增加電場強度，並降低達到特定電場強度所需的電壓。在第三章中，研究強調了精確摻雜分佈和材料特性對單光子雪崩二極體性能的重要性。二氧化矽(SiO2)用於有效隔離，而硼和磷摻雜則形成p型和n型區域。此研究展示了2DDDCC模擬軟體可以準確預測單光子雪崩二極體表現，提供對電場強度分佈、撞擊載子離子化率和電流電壓特性的深入了解。這些發現可以為優化低光成像和量子資訊處理應用的單光子雪崩二極體設計奠定了基礎

This thesis presents a detailed study of Single-Photon Avalanche Diodes (SPADs) and an all-silicon avalanche photodiode (APD) with a microring resonator integrated with a p+pn+ junction(in Chapter 2) designed for telecommunication band applications. Initial simulations reveal shallow dark current below 0.1 nanoamperes up to 7 V, indicating minimal defects and adequate insulation. At 2 V, the onset of impact ionization is observed, leading to breakdown at 7 V with rapid current rise due to electron multiplication. N_A and N_D significantly influenced electric field distribution and breakdown voltage, with acceptor and donor densities resulting in narrower depletion regions and higher electric fields. At zero bias (equilibrium), the SPAD's band diagram shows moderate band bending at the pn junction. Applying a reverse bias of 5V widens the depletion region, enhancing electron-hole separation. At 10V, the intensified electric field causes impact ionization. By 15V, the electric field sustains continuous avalanche multiplication, significantly increasing the photocurrent. Densities critically affect the electric field distribution: higher N_A narrow the depletion region and raise the electric field for a given voltage. Higher N_D similarly narrows the depletion region and increases the electric field, lowering the voltage needed for specific field strength. In Chapter 3, The research emphasizes the importance of precise doping profiles and material properties in determining SPAD performance. Silicon dioxide (SiO2) is used for effective isolation, while boron and phosphorus doping create p-type and n-type regions. The study demonstrates the 2D-DDCC simulation model's capability in accurately predicting SPAD behavior, providing insights into electric field distributions, impact ionization rates, and I-V characteristics. These findings lay a foundation for optimizing SPAD design for applications in low-light imaging and quantum information processing.