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    Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/66893

    Title: 掩埋於氮化矽中的鍺量子點及應用於可見光光偵測器最佳工程化研究;Matrix Engineering of Ge Quantum-dot for Visible Photodetection Applications
    Authors: 簡中彥;Chien,Chung-yen
    Contributors: 電機工程學系
    Keywords: ;量子點;光偵測器;Germanium;Quantum dot;Photodiodes
    Date: 2014-11-25
    Issue Date: 2015-03-16 15:58:38 (UTC+8)
    Publisher: 國立中央大學
    Abstract: 本篇論文系統性地探討了一個新穎的鍺量子點催化鄰近含矽層的氧化現象,以及其所產生的鍺量子點移動遷移行為。同時也研究了鍺量子點的內部結構、應力、光激發螢光譜線與光電特性。在此,我們提出一個矽溶入鍺量子點,再進一步擴散至量子點的尾端氧化的兩步驟機制來解釋所觀察到的鍺量子點在含矽層中移動的特殊現象。從氧化複晶矽鍺/氮化矽異質結構的實驗可知,鍺量子點的大小、形貌與空間分佈深深地受到氧化條件與鄰近區域是否有含矽層材料的存在影響。接著,透過溫度與光強度相依的光激發螢光譜線分析可知,熱應力與量子侷限效應的聯合用使鍺量子點具有準直接能隙的特性,並發出肉眼可見的螢光。
    以鍺量子點為催化劑的兩階段分解與氧化含矽層的機制為基礎,我們發展了類似千層派堆疊氧化矽鍺的技術,並實作展示了一個簡單、可調控的方法來形成量子點大小均勻或漸變三維鍺量子點陣列。最後,我們也製作出了可調變偵測波長的鍺量子點金氧半光偵測器。此光偵測器的光暗電流比值與鍺量子點在閘介電層中的總體積和閘介電層的厚度息息相關。我們所製作出的鍺量子點金氧半光偵測器具有極低的暗電流(1.5×10-3 mA/cm2) 、優越的光暗電流比值(13500) 、高的光響應度(2.2 A/W) 和快的響應時間(5 ns) ,具有可直接與主流的矽基互補式金氧半電路的整合性。
    ;This thesis demonstrates a novel migration phenomenon of Ge quantum dot (QD), which catalytically enhances the local oxidation of underlying silicon-containing layers during the planar oxidation of poly-Si1-xGex/Si3N4 heterostructures over the Si substrate. The internal structure, crystal morphology, and chemical composition of Ge QDs formed in this manner are systematically investigated, and consequently a two-step mechanism has been proposed to explain the unique migration behavior of Ge QDs in Si-containing layers. First, the Ge QD enhances the decomposition of Si-containing layers to release Si interstitials. Subsequently, released Si interstitials diffuse through the Ge QD or its surface and eventually get oxidized beyond the Ge QD, leading to the movement of Ge QD. Accordingly, the size, morphology, and spatial distribution of the Ge QDs are significantly influenced by the oxidation conditions and the underlying silicon-containing layers. Temperature- and power-dependent photoluminescence (PL) analysis suggested that the PL emission on the visible wavelength of Ge QDs embedded in SiO2/Si3N4 matrices is a consequence of exciton recombination of Ge QDs thanks to combined effects of strain and quantum confinement.
    Based on this approach, this thesis further proposes a simple and controllable growth method for placing dense 3D Ge QD arrays in a uniform or a graded distribution by thermally oxidizing stacked poly-SiGe/Si3N4 in a layer-cake technique. Moreover, Ge-QD metal-oxide-semiconductor (MOS) photodetectors were fabricated and featured low dark current density (1.5×10-3 mA/cm2), superior photo-current-to-dark-current ratio (13 500), high photoresponsivity (2.2 A/W), and fast response time (5 ns), showing a great promise for direct integration with prevailing Si complementary metal-oxide-semiconductor (CMOS) electronic circuits. It is also worth to point out that the photo-current-to-dark-current ratio exhibits a strong dependence on the volume of Ge QD in the gate dielectrics and effective gate dielectric thickness.
    Appears in Collections:[電機工程研究所] 博碩士論文

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