矽塊材為非直接能隙的材料，但在尺寸奈米化後，因量子侷限效應使矽量子點具有直接能隙的特性，使得具矽量子點的矽材料可應用於發光元件、太陽能電池、光偵測器等。製作矽量子點常見的方法有濺鍍法、蒸鍍法、化學氣相沉積法，離子束濺鍍法等，其中濺鍍法因成本低、均勻性高且可在室溫下沉積，成為本論文使用的方法之一，而離子束輔助鍍膜則可增進薄膜品質。在本論文中我們從使用濺鍍法製作富矽氧化物薄膜研究開始，進而配合離子源輔助濺鍍法製作富矽氧化物薄膜與富矽氧化物/二氧化矽多層結構，探討其材料性質與光電特性。
1.矽/二氧化矽 (Si/SiO2) 自組裝超晶格結構
富矽氧化物 (SiOx, x≦2) 薄膜使用反應式濺鍍沉積，藉由穿透式電子顯微鏡觀察可發現富矽氧化物 (SiOx, 1.3≦x≦2) 薄膜在未退火時因具有壓應力使薄膜產生週期性的Si/SiO2結構，間距的週期可由調變鍍膜時氧氣流量控制。最後，利用Helmholtz自由能連續性方程說明週期性間隔與薄膜成份的關係。
2.富矽氧化物薄膜
利用低能離子束輔助濺鍍法製作具矽量子點的富矽氧化物薄膜，藉由穿透式電子顯微鏡的觀察與X光繞射分析，發現富矽氧化物薄膜在離子束輔助製程下能增加其結晶性，並可藉由控制離子束能量與鍍膜過程中的氧分壓，將奈米矽晶的尺寸與密度作一微調。離子束輔助濺鍍富矽氧化物薄膜在低氧分條件下，具有較明顯的相分離現象。由氧化實驗發現，富矽氧化物薄膜的位於長波長的光激螢光是由矽奈米晶的量子限制效應所造成。
3.富矽氧化物/二氧化矽超晶格
富矽氧化物/二氧化矽超晶格結構藉由低能量（<60 eV）氬離子束輔助濺射製備，探討其超晶格的材料性質與光激螢光特性。使用離子束輔助濺鍍法製作富矽氧化物薄膜，在退火後薄膜內矽量子點的密度與表面粗糙度皆增加。此外，富矽氧化物薄膜成份並不隨著離子源的加入而改變，但經離子束處理後的富矽氧化物/二氧化矽超晶格結構卻具有較明顯的相分離特性。薄膜中的E’缺陷增加而使得原本橘紅色的光致發光轉為白光。
4.富矽氧化物/二氧化矽多層膜發光元件
藉由調控薄膜沉積的基板溫度、矽量子點的尺寸分布、離子源處理的條件製作富矽氧化物/二氧化矽多層膜發光元件，並探討其發光效率與電子電洞的複合行為。高載子注入能障與矽量子點尺寸的縮小為富矽氧化物/二氧化矽多層膜發光效率增加的主因。若以離子束輔助濺鍍製作富矽氧化物/二氧化矽多層膜中二氧化矽薄膜，因載子注入能障增高使得載子在矽量子點中的侷限時間拉長，導致發光效率增加。最後，利用交流阻抗分析法探討不同頻率下元件的電性行為。

Si-rich oxide (SRO) with embedded Si nanostructures has attracted considerable attention owing to pronounced quantum effect after annealing, regardless of the indirect band-gap nature of Si. The quantum-confinement properties of Si nanocrystals (NCs) have great potential for applications in light emission devices, photodetectors, and solar cells. Many methods have been reported to prepare the Si NCs embedded in SRO films, including sputtering, evaporation, and plasma-enhanced chemical vapor deposition. Among them, sputtering has several advantages superior to other methods such as low substrate temperature, low cost and good adhesion with substrates. Ion beam is another technique that has been developed to assist depositing optical thin films, particularly used together with evaporation to improve film quality. In this thesis, we prepared SRO films and SRO/SiO2 superlattices by sputtering and ion-beam-assisted sputtering (IBAS), and discus the material characteristic and optoelectric properties.
1. Self-assembled Si/SiO2 superlattice
This work involves as-prepared SiOx (x≦2) films that were deposited by reactive sputtering. The regular Si/SiO2 superlattices were self-assembled without post-annealing. The periodicity of Si/SiO2 superlattices was modulated by varying the oxygen flow rate, and was associated with x in SiOx in the range 2-1.3. Si/SiO2 superlattices were formed under compressive stress. The continuity equation of transport and the additional term in the Helmholtz free energy were used to explain the periodicity and the lower limit of the superlattices, respectively.
2. Si-rich oxide films
This study exploits the material and optical properties of Si NCs-embedded SRO films prepared by low-energy IBAS. Transmission electron microscopy and X-ray diffraction revealed that the IBAS improved crystallinity of the annealed SRO films. The size and density of Si NCs can be fine-tuned by ion-beam energy and oxygen partial pressure. The phase separation of IBAS-prepared SRO films was enhanced after annealing. This fact was particularly pronounced at low-oxygen partial pressure condition. Visible photoluminescence of the IBAS films was obtained, owing to the quantum confinement effect of Si NCs.
3. Si-rich oxide/SiO2 superlattices
This study presents the structure and luminescence properties of SRO/SiO2 superlattices in which the SRO layers were prepared by low-energy (<60 eV) argon ion-beam-assisted sputtering. Experimental evidence indicates that the density of the Si NCs in the SRO layer was increased by ion-beam treatment after annealing, increasing the surface roughness. Moreover, the stoichiometry of the as-prepared SRO layer was unchanged but the phase separation of the annealed SRO layer was enhanced by the ion-beam treatment, yielding visible white photoluminescence from the E’ centers and Si nanocrystals.
4. Si-rich oxide/SiO2 superlattice LEDs
The SRO/SiO2 superlattices LEDs were prepared by varying the structure, substrate temperature, and ion source treatment was reported. The electroluminescences of SRO/SiO2 multilayers were associated with the injection barrier height and Si dots size. The retention time of SRO/SiO2 superlattice deposited by IBAS was longer than that prepared by sputtering. Impedance spectroscopy analyses were to realize the electrical properties of materials and their interfaces.

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