矽基光偵測器研製與整合於光學波導系統;Investigation of Silicon-Based Photodetector and Integration to Optical Waveguide System

Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/68304

Title:	矽基光偵測器研製與整合於光學波導系統;Investigation of Silicon-Based Photodetector and Integration to Optical Waveguide System
Authors:	佘貴慧;She,Guei-Huei
Contributors:	光電科學與工程學系
Keywords:	矽基光偵測器;金屬-半導體-金屬;金屬-絕緣層-半導體;Si-based photodetector;MSM;MIS
Date:	2015-07-22
Issue Date:	2015-09-23 11:15:15 (UTC+8)
Publisher:	國立中央大學
Abstract:	本論文提出三種不同結構的850nm光源之矽基光檢測器(Si-based Photodetector)，不但有低溫(室溫)製程與製作簡易之優點，更可藉由調變薄膜厚度提升光偵測器之效能，並成功將所研究之光檢測器整合於矽基光學波導平台系統，未來對於微機電系統整合具有極大的潛力。微機電系統(MEMS)為現在產業趨勢，目前系統中之主動元件常見材料為三五族化合物、鍺(Ge)等，但其有高成本與整合困難等缺點，因此研發矽基光偵測元件製作成本較低、製程技術也非常成熟，而且容易達到積體化及微小化。本研究以金屬-半導體-金屬(Metal-Semiconductor-Metal, MSM)結構矽基光偵測器為主軸。光偵測器元件退火方式進行優化，但我們利用直流式真空濺鍍系統(DC sputter system )於室溫環境下成長透明導電膜氧化銦錫(In2O3:Sn ,ITO)，並製作成元件。此材料兼具抗反射和有效收集載子等特性，搭配最佳抗反射層厚度得到0.63 A/W的光響應。為了提高訊雜比、降低暗電流且不影響光響應的情況下，針對MSM結構進行優化，方法為於氧化銦錫和矽基板間插入一層5nm的二氧化矽形成金屬-絕緣體-半導體(Metal-Insulator-Semiconductor, MIS)結構，插入絕緣層可使蕭基特能障由0.53 eV (SiO2=0nm)提升至0.64eV (SiO2=5nm)，使暗電流降低兩個數量級，光暗電流訊雜比由13.7提升至309，光響應為0.51 A/W。而本實驗為了配合矽基光學波導平台內的高分子聚合物，使用120 oC、2分鐘退火參數優化MIS光偵測器，使暗電流密度由1.89×〖10〗^(-3) A/cm2至4.04×〖10〗^(-5) A/cm2，光電流部分由1.42×〖10〗^(-3) A提升至1.84×〖10〗^(-3) A。整合於矽基光學波導系統選擇傳統PN結溝光偵測器，其二極體接面使用技術純熟、傳統的離子佈植形成二極體接面搭配退火活化並蓋上一層抗反射二氧化矽層使光響應提升1.5倍，達0.32 A/W。完整比較三種不同結構光偵測器元件，選擇技術成熟PN光偵測器並成功其整合於矽基光學波導平台，並比較元件和整合於系統端之光偵測器特性表現。元件利用退火900 oC、1分鐘修補晶格缺陷搭配抗反射層可使光響應達0.32 A/W，暗電流為2.74×〖10〗^(-7)A，而系統端光響應可達0.28 A/W，暗電流6.49×〖10〗^(-6) A。 ;In this research, we propose the three different structures of Si-based photodetector for the light source of 850 nm. We modulated thickness of film to improve efficiency of the photodetector at low temperature with brief fabrication steps and successfully integrated it to the Si-based optical waveguide bench. There is great potentiality to apply this technique to the MEMS system in the future. Nowadays, MEMS is getting popular in the industry but Ⅲ-Ⅴcompound is high cost and difficult to fabricate to the active components which are used in MEMS system. Therefore, the Si-based photodetector is a good choice to promote the development of MEMS system because of low cost, mature fabrication technology, convenient to reduce scale and integration. In this investigation, we focused on the structure of Metal-Semiconductor-Metal Si-based Photodetector. Annealing which can improve film quality or good ohmic contact is the common way to optimize the components but we used DC sputter system to sputter athe layer of transparent conducting oxide, In2O3: Sn (ITO) which provides good anti-reflection and efficient electrons or holes collection. The layer is used to fabricate photodetector components and the best responsivity is 0.79 A/W with anti-reflection layer for 850nm. In order to improve MSM structure by inducing the Iphoto/ Idark ratio、decreasing dark current without impacting on responsivity, we inserted the layer about 3.5nm SiO2 between ITO and N-type Silicon to form Metal-Insulator-Semiconductor structure. Because of the insulator, the Schottky barrier height was induced from 0.53eV (SiO2=0nm) to 0.64eV (SiO2=3.5nm) and the dark current was reduced by two orders of magnitude and the Iphoto/ Idark ratio was enhanced from 13.7 to 309, the responsivity of MIS photodetector was 0.51 A/W. Then, we optimized MIS photodetector at 120 oC process for 2 minutes. The result was that the dark current density was reduced from 1.89×〖10〗^(-3) A/cm2 to 4.04×〖10〗^(-5) A/cm2 and the photo current was increasing from 1.42×〖10〗^(-3) A to 1.84×〖10〗^(-3) A. In addition to MSM and MIS structures, we choosed PN photodetector that formed diode junction by traditional ion implantation as a reference. The responsivity of PN photodetector was 1.5 times larger than the one without anti-reflection layer. The responsivity of PN photodetector with anti-reflection was 0.32 A/W. We have compared three different structure of photodetectors; in addition it was successful to integrate the PN photodetector to the Si-based optical waveguide bench. Then, the PN photodetector component was compared with it that integrating in system. The responsivity of PN photodetector component was 0.33 A/W and the dark current was 2.74×〖10〗^(-7)A. Otherwise, the responsivity of photodetector in system was 0.28 A/W and the dark current was 6.49×〖10〗^(-6) A.
Appears in Collections:	[光電科學研究所] 博碩士論文

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