利用原子層沉積法臨場摻雜鋁氧化鋅薄膜披覆于氧化鋅奈米線之結構與光電特性研究

Abstract

本論文研究利用原子層沉積技術臨場摻雜鋁氧化鋅薄膜披覆于氧化鋅奈米線之結構與光電特性。實驗共分為三個部分：首先使用原子層沉積系統(ALD)成長摻鋁氧化鋅(AZO)薄膜在m-平面藍寶石基板上。在260 °C所成長的摻鋁氧化鋅薄膜經由X光繞射(XRD)結果只有氧化鋅(100)繞射峰，且其結晶性最好，X光反射率(XRR)結果顯示其薄膜品質亦較平整，霍爾量測結果其片電阻為97 ohm/sq.，載子遷移率為16 cm2/Vs；其次為使用垂直式高溫爐成長氧化鋅奈米結構在鍍金的矽基板上。掃描式電子顯微鏡(SEM)結果顯示在基板溫度700 °C以及氬氣流量800 sccm時其形貌為奈米線結構；最後部分為使用原子層沉積系統成長不同厚度的摻鋁氧化鋅薄膜在氧化鋅奈米線上。掃描式電子顯微鏡結果顯示摻鋁氧化鋅薄膜可均勻完整的披覆在氧化鋅奈米線上。掠角X光繞射(GIXRD)結果顯示：隨著摻鋁氧化鋅披覆的厚度越厚，氧化鋅(100)及(101)繞射峰訊號會增強。光激螢光光譜(PL)顯示氧化鋅奈米線與摻鋁氧化鋅薄膜披覆氧化鋅奈米線無綠光區，而披覆上摻鋁氧化鋅薄膜後則有藍移的現象。四點探針量測結果顯示氧化鋅奈米線經由披覆摻鋁氧化鋅薄膜之後，片電阻有明顯的下降，且隨著披覆厚度越厚而越低；場發射量測結果顯示在100週期之摻鋁氧化鋅薄膜披覆在氧化鋅奈米線上，存在最低起始電壓20 V/μm，最大電流密度為2 mA/cm2，場發射增強因子β為465。

The thesis was consist in three parts: At first, aluminum doped zinc oxide(AZO) thin film was deposited on m-plane sapphire grown by Atomic Layer Deposition (ALD). For the AZO film grown at 260 oC, X-ray measurement showed that AZO film only presented zinc oxide (ZnO) (100) diffraction peak. It also had the best crystallinity with smooth film surface. The Hall measurement showed that sheet resistance was as low as 97 ohm/sq with mobility~ 16cm2/Vs. Second, ZnO nanowire was grown on Au-coated Si (100) substrate by a vertical high temperature furnace. For a substrate temperature at 700 oC with the 800 sccm of argon flow, ZnO nanowires were successfully formed. Finally, ZnO nanowires coated with varied thicknesses of AZO films prepared by ALD. The SEM measurement showed that AZO thin film coated uniformly on the ZnO nanowires. The GIXRD results showed that the increase of the ZnO (100) and (101) diffraction peak with increasing the thickness of AZO film coated. The PL spectrum showed that both of as-grow ZnO nanowires and the AZO film coated on ZnO nanowires exhibit without the green emission, but with blue shift for the AZO films coated on ZnO nanowires. The Hall measurement showed the decrease of sheet resistance with increasing the thickness of AZO coated films. For the ZnO nanowires coated with 100 ALD cycles of AZO films have the lowest turn-on field ~ 20 V/μm and the maximum current density ~ 2 mA/cm2 and the field enhancement factor is about 465.