- 學位論文
脈衝雷射蒸鍍法製備氧化鋅摻鉍薄膜之研究
Study on Bi-doped ZnO Thin Films Fabricated by Pulsed Laser Deposition
摘要
本論文利用脈衝雷射蒸鍍法(Pulsed laser deposition, PLD)在C面藍寶石基板(c-plane Sapphire)上沉積氧化鋅摻鉍薄膜，並且量測其結構、電學與光學特性。本實驗所使用的雷射光源為Nd：YAG雷射並透過非線性晶體將四倍頻波長266nm輸出，脈衝寬度<10ns，脈衝頻率為10Hz。所使用的靶材為自製高溫燒結氧化鋅摻鉍靶材；薄膜之平均膜厚為300nm。實驗中探討了不同製程溫度、環境氧壓與退火條件之下成長之ZnO:Bi薄膜之特性。 薄膜之晶體結構與表面形貌分別由X光繞射儀、掃描式電子顯微鏡及原子力顯微鏡量測，在10at%靶材濃度以下成長之薄膜其晶格為c軸取向且薄膜呈現顆粒狀分布；薄膜光學特性由光激螢光光譜儀以及穿透光譜儀量測，PL量測指出在不同低氧壓條件下與退火前後的缺陷光峰值位置會發生變化，間接證實了氧間隙對於p-type薄膜形成條件的影響。穿透光譜分析薄膜的穿透率可高達90%；最後霍爾量測分析電學特性，結果顯示出薄膜電性對於成長的氧壓非常敏感。薄膜之電阻率為0.028~0.35Ω-cm、遷移率4.79 ~ 34.4 cm2/V•s、載子濃度為7.94x1016 ~ 1.04x1019cm-3。
並列摘要
In this study, bismuth-doped ZnO thin films were fabricated by pulsed laser deposition (PLD) on c-plane sapphire. The Nd：YAG Q-switched laser with 266 nm wavelength was used for ablating the ZnO:Bi targets made by sintering ZnO and Bi2O3 powder under high temperature. Effects of substrate temperature, ambient oxygen pressure and different conditions of annealing procedure were studied. Doped films prepared by ZnO:Bi targets below 10at% show clear c-axis(002) orientation which were characterized by x-ray diffractometer. The SEM images showed quite smooth surfaces with dense grains on our films. The transparency in the visible region of ZnO:Bi films is about 80~90% observed from Transmittance spectra. We obtained low resistivity ZnO:Bi thin films under the fabricated condition of relatively low oxygen pressure. Furthermore, our films showed strong P-type conductivity and the resistivity is about 0.028~0.35Ω-cm, carrier mobility: 4.79 ~ 34.4 cm2/V•s, and carrier concentration is about 7.94x1016 ~ 1.04x1019cm-3.