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標題: | 富矽碳化矽薄膜太陽能電池 Si-rich Silicon Carbide Thin-Film Solar Cells |
作者: | Tzu-Chieh Lo 羅子傑 |
指導教授: | 林恭如(Gong-Ru Lin) |
關鍵字: | 電漿輔助化學氣相沉積,富矽碳化矽,奈米矽晶,碳化矽薄膜太陽能電池, PECVD,Si-rich Si1-xCx,silicon nanocrystal,SiC thin film solar cell, |
出版年 : | 2010 |
學位: | 碩士 |
摘要: | 本論文藉由電漿輔助化學氣相沉積系統成長富矽碳化矽薄膜,在調變氣體流量比,腔體壓力,射頻功率,改變基板溫度 250至450℃製程參數之下進行成膜品質分析。據 SIMS分析觀察到基板溫度影響薄膜與氧原子的結合導致結晶碳化矽材料的劣化。在較低的250℃基板溫度成長樣本退火後氧原子侵入整層碳化矽薄膜且氧含量SIMS強度讀值在9.7×105。相同的氧化情形可在XPS分析中呈現,經過高溫處理從Si-C, C-C sp3, C=C sp2鍵結的退化及O-Si-O鍵結的增強可證明碳化矽膜的相變。相反地,提升基板溫度至450℃條件下成長,碳化矽膜氧化的情形停止在靠近表面約20nm,且氧元素強度從9.6×105降至4.0×105。
透過選擇在薄膜沉積過程中以氬氣預稀釋腔體殘氧,以及氬氣保護下進行覆蓋式退火,可以進一步穩定碳化矽鍵結並阻止成膜氧化。在溫度拉升至1050℃且持續30分鐘退火後,經由HR-TEM得到自我聚集奈米矽的直接證據。奈米矽晶的直徑以及密度分別為3±1 nm和4.35×1018 cm-3。富矽碳化矽基ITO/n-SiC/p-Si/Al薄膜太陽能電池的電流-電壓特性曲線,隨著成長n型碳化矽參雜氣體PH3濃度從1%至5%而變化,開路電壓由72.5 升高至205.8 mV,短路電流由0.93 提升至 3.01 mA/cm2,在參雜氣體PH3濃度為5%時獲得單層n型富矽碳化矽薄膜太陽能電池轉換效率為0.16%。 The non-stoichiometric silicon carbide (Si1-xCx) film deposited by plasma enhanced chemical vapor deposition (PECVD) system. At the same gaseous flow ratio, chamber pressure and RF power, changing substrate temperature 250 and 450℃ affect the different deposition condition. According to the SIMS analysis, we observe that the substrate plays an important role on the oxygen-exclusive synthesis and stabilized crystallization of SiC material. In s250 sample annealing 850℃ for 10 min, the oxygen content invaded entire film under 250℃ lower substrate temperature deposition condition and the intensity of O rose to 9.7×105 counts. In addition, silicon atoms content decreased to only 0.3×105 counts and carbon atoms content almost vanished in the film. On the contrary, in s450 sample, the oxidation depth is about 20 nm and the O element component intensity from 9.6×105 counts return to 4.0×105 counts. The same tendency illustrate in XPS measurement, the phase transformation of Si-C to relatively strong SiO2 and graphite/diamond related Si(2p3) and C(1s) XPS signals can be obtained from the oxidized SiC with numerous Si-O and C-C bonds formed during annealing. The solution to solve incorporated oxygen deposition and better stacking sequence of crystalline structure is increasing deposition temperature as shown in SIMS analysis. Moreover, we not only purge chamber by Ar gas during vacuum but also make use of Ar gas substitute for N2 as furnace annealing gas. However, the self-assembled Si starts to appear with increase annealing temperature up to 850℃. The volume density of Si-QDs, with an average diameter of 3±1 nm formatted in annealed Si-rich S1-xCx, is controlled at 4.35×1018 cm-3 after 1050℃ annealing temperature by HR-TEM image analysis. The I-V characteristic of SiC thin film solar cells: ITO/n-type SiC/p-type Si/Al, the open current voltage (Voc) increase from 72.5 to 205.8 mV, and the short current density (Jsc) enhance from 0.93 to 3.01 mA/cm2 with rising PH3 doping concentration from 0.47% to 5%. With 5% PH3 doping concentration, the solar cell conversion efficiency of the n-SiC based sample is 0.16%. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/47857 |
全文授權: | 有償授權 |
顯示於系所單位: | 光電工程學研究所 |
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