氧化鋅奈米線/奈米鑽石薄膜複合結構之特性研究
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2009
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Abstract
氧化鋅(ZnO)為一寬能帶間隙半導體材料，並且擁有許多吸引人的特性，例如奈米結構多變性、室溫下有很高的發光效率和高激子束縛能、高壓電特性、無毒性可應用於光電生醫方面。在本論文中使用氧化鋅奈米線(Zinc oxide nanowires, ZnO NW)和奈米鑽石薄膜(nanocrystalline diamond thin films, ND)製作複合結構，首先利用微波電漿化學氣相沉積系統成長奈米鑽石薄膜，接著分別利用水熱法以及VLS 法成長氧化鋅奈米線於奈米鑽石薄膜上。
研究結果發現水熱法成長氧化鋅奈米線/奈米鑽石薄膜複合結構之場發射起始電場可降低至5.6 V/μm、場增強因子為1286。VLS法成長氧化鋅奈米線/奈米鑽石薄膜結構之場發射起始電場為6.5 V/μm、場增強因子為1565，與單純奈米鑽石薄膜比較，證實成長氧化鋅奈米線於奈米鑽石薄膜上之複合結構有效提升場發射特性。單純氧化鋅奈米線之電漿後處理場發射特性結果發現，分別以氬氣電漿作用1、3、5分鐘後，發現氬氣電漿處理1分鐘可降低起始電場至12.4 V/μm、提升場增強因子至526。以氫氣電漿作用1、3、5分鐘後，得到結果為氫氣電漿處理3分鐘可降低起始電場至10.6 V/μm、提升場增強因子至903。綜合VLS法成長複合結構與氫電漿處理3分鐘之試片，起始電場為6.6 V/μm、場增強因子為1951，與前述之複合結構比較後，證實綜合VLS法成長複合結構與氫電漿處理3分鐘之試片擁有較佳的場發射特性。
In this study, the nanocrystalline diamond film was deposited on silicon substrate using methane/hydrogen/oxygen (30/169/0.2 sccm) mixed gas by microwave plasma chemical vapor deposition (MPCVD) system. Different synthetic techniques, hydrothermal technique and vapor liquid solid (VLS) technique, are used to grow Zinc oxide (ZnO) nanowires on nanocrystalline diamond films (nano-diamond films). For the hydrothermal technique, a 180 nm thick of ZnO film is coated as a seeded layer on nano-diamond film. ZnO nanowires are grown by immersing in a mixture of solution (Zinc nitrate (Zn(NO3)2 . 6H2O) and Hexamethylenetetramine (HMTA) in deionized water) at 90 oC for 3 hours. For the VLS technique, a 10 nm thick of Au layer is coated on nano-diamond films as catalyst. ZnO nanowires are synthesized using a mixture of ZnO and graphite powder as the source in a furnace at 850 oC with 100 sccm of Ar gas at 20 torr for 30 min. However, it is indicated that the field enhancement factor are both improved for the ZnO/nano-diamond structure compared to ZnO/Si structure by hydrothermal (307 to 1286) and by VLS (386 to 1565). ZnO nanowires are treated by Ar and H2 plasma for 1, 3 and 5 min. It is observed that the field enhancement factor of Ar plasma treatment for 1 min are 526. It is noted that the turn on field and critical current density of H2 plasma treatment for 3 min are 903. The best condition of turn on field and field enhancement factor are 6.6 V/μm and 1951, which is obtained from the VLS ZnO NW/ND and then treated by H2 plasma for 3 min.
In this study, the nanocrystalline diamond film was deposited on silicon substrate using methane/hydrogen/oxygen (30/169/0.2 sccm) mixed gas by microwave plasma chemical vapor deposition (MPCVD) system. Different synthetic techniques, hydrothermal technique and vapor liquid solid (VLS) technique, are used to grow Zinc oxide (ZnO) nanowires on nanocrystalline diamond films (nano-diamond films). For the hydrothermal technique, a 180 nm thick of ZnO film is coated as a seeded layer on nano-diamond film. ZnO nanowires are grown by immersing in a mixture of solution (Zinc nitrate (Zn(NO3)2 . 6H2O) and Hexamethylenetetramine (HMTA) in deionized water) at 90 oC for 3 hours. For the VLS technique, a 10 nm thick of Au layer is coated on nano-diamond films as catalyst. ZnO nanowires are synthesized using a mixture of ZnO and graphite powder as the source in a furnace at 850 oC with 100 sccm of Ar gas at 20 torr for 30 min. However, it is indicated that the field enhancement factor are both improved for the ZnO/nano-diamond structure compared to ZnO/Si structure by hydrothermal (307 to 1286) and by VLS (386 to 1565). ZnO nanowires are treated by Ar and H2 plasma for 1, 3 and 5 min. It is observed that the field enhancement factor of Ar plasma treatment for 1 min are 526. It is noted that the turn on field and critical current density of H2 plasma treatment for 3 min are 903. The best condition of turn on field and field enhancement factor are 6.6 V/μm and 1951, which is obtained from the VLS ZnO NW/ND and then treated by H2 plasma for 3 min.
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Keywords
氧化鋅奈米線, 奈米鑽石薄膜, 場發射, 電漿處理, ZnO nanowires, nanodiamond films, field emission, plasma treatment