以二氧化矽/矽為基礎之積體光學元件，由於其具有較低之熱膨脹係數、與微電子系統之高整合性以及在光通訊使用之主要視見區(波長1.3 and 1.53 μm)有極高的穿透性，因此對於以二氧化矽作為基礎製備之薄膜，製作光通訊元件如摻鉺放大器等，極具潛力。摻鉺原子被激發後會放出約1.53 μm的紅外光，經相位整合後有放大光通訊訊號之效果。
　　本研究分為兩個部分，第一部份為使用矽酸四乙酯(TEOS)及四異丙烷氧化鈦(TTIP)做為前導液原始材料，以溶膠凝膠法製備二氧化矽-二氧化鈦複合氧化膜。初鍍及經退火處理之薄膜的組成成分、結晶結構及化學鍵結利用拉賽福背向式散射儀、低掠角X光繞射儀、傅立葉轉換紅外線光譜儀及X光光電子能譜儀進行分析；薄膜光學性質則由橢圓儀及紫外光-可見光光譜儀分別量測。研究中所標示之組成比例均為實驗時前導液混合之TEOS/(TEOS+TTIP)比例。由分析結果發現，當TEOS/(TEOS +TTIP)添加比例到達40%以上時，薄膜即使經700oC退火，仍能保持非晶質結構；而隨著TTIP添加量增加，薄膜之折射率亦呈現線性增加；但二氧化矽比例較多之薄膜，其穿透率高於二氧化鈦比例較多之薄膜。另外，在TEOS:TTIP為80%:20%時，薄膜具有數量最多之Si-O-Ti鍵結，而當TTIP的添加量增加時，二氧化矽及二氧化鈦會傾向相分離，而減少Si-O-Ti的鍵結數量。
　　第二部分是根據第一部份之實驗結果，摻雜鉺元素於TEOS: TTIP = 80:20之二氧化矽-二氧化鈦複合氧化膜中，選用之原因為基於此比例之薄膜具有較高的Si-O-Ti的鍵結量。其薄膜結晶結構及化學鍵結分析儀器同第一部份，另外使用微光激發光光譜分析薄膜光學性質。並由於鉺之添加量極為微量，因此使用國家同步輻射中心之延伸X光吸收細微結構光譜研究鉺原子周圍之鍵結結構。分析結果發現，添加鉺對於80%SiO2-20%TiO2薄膜之整體結晶性沒有大太的影響，不同添加比例之鉺原子第一層鄰近原子都為氧，鉺與氧鍵結形成發光中心，但其配位數介於6~8之間。與微激發光光譜之結果比較發現，鉺之配位數對發光強度有明顯之影響，當鉺添加量為1 mol%於80%SiO2-20%TiO2中，經700oC退火，波長為1536nm之發光強度最強且鉺與氧之配位數最低；就PL實驗分析而言，摻鉺於Si-O-Ti 鍵結量較少之40%SiO2-60%TiO2薄膜作為對照組發現，80%SiO2-20% TiO2-Er之發光強度高於40%SiO2-60%TiO2-Er，故推測Si-O-Ti鍵結對於發光強度有幫助。原子微結構對於光學性質之影響將在本論文中詳加探討。

　　SiO2/Si-based integrated optic devices and circuits have a great benefit to the high-speed telecommunication according to the small thermal expansion mismatches of SiO2 on Si substrate, excellent compatibility with microelectronics, and the high transparency in the major communication windows of optical fiber transmission (1.3 and 1.55 μm wavelength). The derivative optical component such as Erbium-doped fiber amplifier is based on the foundation of these properties.
　　Thin films of SiO2-TiO2 composite oxides with various SiO2:TiO2 compositions were prepared by sol-gel method, using tetraethylortho- silicate (TEOS) and titanium tetraisopropoxide (TTIP) as precursors. The composition, crystal structure and chemical bonding configuration of the as-deposited and annealed SiO2-TiO2 thin films were analyzed by using Rutherford backscattering spectrometry (RBS), glancing incident angle X-ray diffraction (GIAXRD), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS), respectively. Optical properties of the films were characterized by spectroscopic ellipsometry and ultraviolet-visible spectrophotometry. The Si/Ti ratios in the SiO2-TiO2 films agree with the TEOS/TTIP molar ratio in the sol-gel precursor. When the TEOS/(TEOS+ TTIP) ratio is greater than 40%, the SiO2-TiO2 thin films remain amorphous after annealing at temperature as high as 700oC. FTIR spectra indicate that the quantity of Si-O-Ti bonding can be maximized when the TEOS:TTIP in the precursor is 80%:20%. The refractive index of the SiO2-TiO2 films increases approximately linearly to the mixing ratio of TTIP/(TEOS+TTIP). However, SiO2-rich films possess higher ultraviolet-visible transmittance than the TiO2-rich films.
　　Er-doped SiO2-TiO2-Er thin films were also prepared by sol-gel method, using TEOS and TTIP as precursors with addition of Erbium nitrate pentahydrate powder. According to the investigation on the SiO2-TiO2 thin films, the 80SiO2-20TiO2 film is selected to dope Erbium. Optical properties of the films were characterized by micro-photoluminescence (Micro-PL). Atomic coordination structure of Erbium was defined by Extended X-ray absorption fine structure spectrometry (EXAFS). XPS and FTIR analyses reveal that the main bonding structures of SiO2-TiO2 thin films are not sensitive to the Er doping. All the atoms adjacent to Erbium are oxygen in various doping concentrations. However, the first-neighbor-shell coordination number of Erbium has influence to the optical properties. The annealed 80%SiO2-20%TiO2-1.0%Er with extremely high PL intensity has lowest coordination number as well. Modification of microstructure in the SiO2-TiO2-Er films and its influence on the optical properties are discussed.

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