多矽氧化矽組成比例對奈米矽基金氧半二極體發光特性分析

在本論文中，在低功率的電漿輔助化學氣相沉積系統內，證實N2O/SiH4流量比例與氧/矽組成比例對於成長最多量奈米矽的富矽氧化矽薄膜有相關性，藉由降低N2O與N2O/SiH4流量比例調整富矽氧化矽的氧/矽組成比率從1.38到0.88且得到類高斯分佈的非線性近紅外光激螢光。降低N2O/SiH4 比率，大量的Si-H吸收鍵結在870與2250 cm-1幫助形成小尺寸奈米矽並且防止表面再氧化。N2O/SiH4比例訂在5.5時，對厚度歸一化的最強光激螢光峰值是在760 nm且此時的氧/矽比為1.24且矽濃度大約44.64 atom %。特別注意的是，N2O流量維持小至25sccm來限制氧解離作用和完全分解SiH4，因此在矽奈米晶表面的懸擺鍵結上產生微量的氫鈍化。N2O：SiH4流量降至5:1且與典型的退火1hr過程相比，退火時間及溫度短至15分鐘1100 oC時達到最佳。HRTEM分析透露如此小的奈米矽晶直徑約為1.5±0.2 nm。由FTIR分析可知，我們推論極低流量的電漿輔助化學氣相沉積可以完全從SiH4分解出Si並且產生極小的氫氣鈍化。使我們易於精確控制矽奈米晶的尺寸和大幅增強藍光光激螢光強度。在外加290V的情況下發現了具有藍光的電激發光現象，相較於PI斜率為0.37mW/A情況下的紅光金氧半二極體光功率為270 nW，藍光金氧半二極體的光功率可達333 nW至500 nW，我們利用低N2O流量製程條件在富矽氧化矽成長出小尺寸高密度奈米矽晶，並以此成功做出高輸出功率的金氧半二極體元件。

關鍵字

電激螢光；光激螢光；奈米矽晶；多矽氧化矽；電漿輔助化學氣相沉積；金氧半

並列摘要

In this thesis, correlation between N2O/SiH4 fluence ratio and O/Si composition ratio for optimizing Si nanocrystal precipitation in Si-rich SiOx grown by low-plasma PECVD is demonstrated. The O/Si composition ratio of SiOx can be adjustable from 1.38 to 0.88 by detuning N2O fluence and N2O/SiH4 ratio to obtain a nonlinearly Gaussian-like dependency with near-infrared photoluminescence (PL). By reducing N2O/SiH4 ratio, abundant Si-H bonds with absorption at 870 and 2250 cm-1 assist small-size Si nanocrystal precipitation and prevent outer surface re-oxidation. Maximum PL at 760 nm at O/Si=1.24 with corresponding Si concentration of 44.64 atom.% is obtained at N2O/SiH4 ratio of 5.5. In particular, the N2O fluence remains as small as 25 sccm to restrict oxygen desorption and to complete SiH4 decomposition, thus minizing the hydrogen passivation on dangling bonds at Si nanocrystal surface. The N2O:SiH4 fluence is decreased to 5:1 and the optimized annealing are achieved as short as 15 min at 1100oC in comparison with typical 1-hr process. HRTEM analysis reveals such tiny Si nanocrystals exhibit diameter of only 1.5±0.2 nm. From FTIR results, we conclude that the ultra-low fluence PECVD can completely decompose the Si from SiH4 with minimum hydrogen passivation, which facilitates the precise control of Si nanocrystal size and greatly enhances the blue PL intensity. The blue-light EL pattern is observed at 290 V for the MOSLED made on SiOx grown at N2O fluence as low as 25 sccm. The maximum emitting power is about 333~500 nW for the blue-light MOSLED as compared to that of 270 nW for red-light MOSLED associated with a PI slope of 0.37 mW/A. Higher output power of MOSLED on low-N2O-fluence grown SiOx is attributed to the smaller Si nanocrystals with larger density.

並列關鍵字

Electroluminescence ； Photoluminescence ； Nanocrystallite Si ； Si-rich SiOx ； PECVD ； Metal-Oxide-Semiconductor

參考文獻

Chapter I

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多矽氧化矽組成比例對奈米矽基金氧半二極體發光特性分析

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