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系統識別號 U0026-0309201417165300
論文名稱(中文) 氧化鋅薄膜之成長與奈米尺度表面電性研究
論文名稱(英文) Study on characterization and nanoscale surface electrical properties of ZnO thin film with different deposition parameters
校院名稱 成功大學
系所名稱(中) 地球科學系
系所名稱(英) Department of Earth Sciences
學年度 102
學期 2
出版年 103
研究生(中文) 陳彰豪
研究生(英文) Chang-Hao Chen
學號 L46011162
學位類別 碩士
語文別 中文
論文頁數 71頁
口試委員 指導教授-陳燕華
口試委員-吳忠霖
口試委員-齊孝定
口試委員-劉浩志
中文關鍵字 氧化鋅薄膜  價態分析  導電性  導電力顯微鏡 
英文關鍵字 ZnO thin film  chemical state  conductivity  CAFM 
學科別分類
中文摘要 氧化鋅薄膜之成長與奈米尺度表面電性研究

陳彰豪,陳燕華*
國立成功大學地球科學系


摘要

氧化鋅為當今廣泛使用的半導體材料之一,可作為壓電材料、表面聲波元件、透明電極等。因此,系統性探討影響氧化鋅導電特性之變因具有其必要及價值。本研究係利用射頻磁控濺鍍系統鍍製不同製程參數之氧化鋅薄膜於導電矽基板上,利用導電力顯微鏡量測不同樣品的導電特性差異,輔以XRD、XPS、AFM對樣品進行結構分析、價態分析、表面特性分析,藉以比較製程參數與導電特性之關聯。結果可得知:氧化鋅薄膜的導電特性與其結構、元素配比、表面特性等皆有關聯,製程上的參數變因使得氧化鋅薄膜的特性變化,確實影響氧化鋅薄膜最終的導電特性。

關鍵字:氧化鋅薄膜,價態分析,導電性,導電力顯微鏡。


介紹

氧化鋅薄膜之導電特性優劣在工業利用上佔有一定的重要性,為此,有不少前人文獻已對影響氧化鋅導電特性的因素做相關研究。但在薄膜製程上,有許多種不同的製程因素會影響薄膜特性之優劣,前人文獻所運用之鍍膜方式及探究的特性亦有所不同,難以有系統性整合之文獻。因此,本研究利用射頻磁控濺鍍系統鍍製氧化鋅薄膜,調控不同的濺鍍功率、工作氣體比例以及基板溫度等參數,利用電漿轟擊鋅靶與工作氣體之氧氣反應形成氧化鋅附著於導電矽基板上,最後以XRD、XPS、CAFM等儀器分析其薄膜特性。在特性分析結果可發現:不同的濺鍍參數確實影響到薄膜最終的導電特性,我們的研究目標則在於探究影響其導電特性的主要因素。



材料及方法

本研究使用射頻磁控濺鍍系統鍍製氧化鋅薄膜,將兩吋金屬鋅(純度99.99%)靶材安裝於濺鍍槍上,靶材距離基板13公分,工作氣壓固定為5 mtorr,濺鍍時間固定為1小時,變動之參數有濺鍍功率(80 W、100 W、120 W)、氬氧比例(2:8、5:5、8:2)及基板溫度(300 °C、400 °C、500 °C)。於CAFM量測上,給予樣品的電壓固定為0.5 V,掃描範圍為1 μm1 μm,訊號放大倍率固定為〖10〗^7倍,使用Pt/Ir合金鍍層之導電探針進行量測。

結果與討論

研究結果發現,各薄膜之XRD繞射圖像均為六方纖鋅礦相,且(002)繞射峰強度明顯優於其他晶面繞射峰,顯示此薄膜具有(00l)優選排列之性質;從AFM影像圖中可了解:隨著薄膜粒徑增加,表面粗糙度也隨之提升;由CAFM的訊號大小可反應出在高濺鍍功率、高氬氣含量與高基板溫度之參數下擁有較佳的導電性;經XPS分析結果可得知:由磁控濺鍍法所製備之氧化鋅薄膜普遍存有氧缺問題,而Zn⁄O劑量比確實會影響氧化鋅薄膜之導電性。
比較XRD、XPS、AFM及CAFM所獲得之結果可發現:(1)氬氧比及基板溫度參數對結晶度與導電性之影響較為明顯、(2)晶體粒徑越大其樣品導電性越佳、(3) Zn⁄O比例確實對導電性影響甚鉅。

結論

我們對於氧化鋅薄膜在製程中可能影響其導電性質的參數進行研究與探討,並比較氧化鋅薄膜各個特性的變化及關連性。比起單一變因,同時探討多個製程變因能夠提供更多的資訊,以期製備出更加導電性更優良的氧化鋅薄膜。
英文摘要 Study on characterization and nanoscale surface electrical properties of ZnO thin film with different deposition parameters

Chang-Hao Chen and Yen-Hua Chen*
Department of Earth Sciences, National Cheng Kung University, Taiwan


SUMMARY

Zinc oxide (ZnO) is one of the popular semiconductors, and it can be used as piezoelectric material, acoustic wave devices, and transparent electrodes etc. Therefore, it is imperative to systematically investigate the conductivity of zinc oxide thin films. In this study, ZnO films with different deposition parameters by using radio frequency sputtering method are fabricated on the conductive Si(100) substrate. The conductivity of the films is measured by conductive atomic force microscopy (CAFM). The crystal structure, chemical state, surface properties are examined by X-ray diffractometer (XRD), X-ray photon spectroscopy (XPS), atomic force microscopy (AFM). The conductivity of ZnO films is related to the crystal structure, oxygen vacancy, and surface characterization. It can be concluded the conductivity of ZnO film would be influenced by the deposition parameters.

Key words: ZnO thin film, chemical state, conductivity, CAFM


INTRODUCTION

The conductivity of ZnO thin films is important for industrial application. Therefore, the research about the conductivity of ZnO films has be studied. However, there are few systematic investigations related to ZnO films. In this research, the deposition parameters, including sputtering power, working pressure, and deposition temperature, are discussed detailedly. The ZnO films are fabricated on Si (100) substracts via a R.F. sputtering deposition. The characterization of ZnO films will be studied by XRD, XPS AFM, and CAFM measurements. The relation between conductivity and deposition parameters of ZnO films is discussed.

MATERIALS AND METHODS

The zinc target (purity of 99.99%) is placed on the sputtering gun, and the distance between the target and the substract is 13 cm. The working pressure is 5 mtorr within a sputtering time of 1 hr via different sputtering power (80, 100, 120 W), pressure ratio (Ar/O2 = 2/8, 5/5, 8/2), and sputtering temperature (300, 400, 500°C). On the CAFM, measurement, the voltage is applied as 0.5 V with a Pt/Ir tip in a scanning size of 1 μm1 μm, and the magnification of current amplifier is 107. The deposition parameters of ZnO films are listed in Table 1.


RESULTS AND DISCUSSION

All of ZnO films are wurtzite structure and the XRD pattern shows a (002) preferred orientation. From AFM images, the surface roughness increases with the increasing particle size of films. The conductivity of ZnO films is enhanced by a higher sputtering power, a larger Ar/O2, and a higher deposition temperature via CAFM measurements. The XPS results show that oxygen vacancy is common existed in ZnO films, which really affect the conductivity of ZnO films.
Compared with the results of XRD, XPS, AFM and CAFM, it can be found: (1) the parameters of Ar/O2 and substract temperature obviously affect the crystallinity and the conductivity, (2) the ZnO film with a larger particle size has a better conductivity, (3) the conductivity is more dominant of the element ratio of Zn/O.

CONCLUSION

The deposition parameters of ZnO films related to conductivity are investigated in this study. Detailed discussion of deposition parameters is helpful to realize the factors related to conductivity and this information could be more useful for industrial application.
論文目次 中文摘要 I
Abstract III
致謝 VI
目錄 VIII
圖目錄 XI
表目錄 XIV
第一章 緒論 1
1-1 導論 1
1-2 研究目的 2
第二章 文獻回顧 3
2-1 材料簡介 3
2-1-1 氧化鋅 3
2-2 薄膜沉積理論 5
2-2-1 薄膜沉積機制 7
2-2-2 薄膜形成之機制 11
2-3 濺鍍原理 13
2-3-1 直流濺鍍與射頻濺鍍 14
2-3-2 磁控濺鍍 15
2-4 導電特性 16
第三章 實驗方法 18
3-1 實驗流程 18
3-1-1 實驗材料 19
3-1-2 實驗設備 20
3-2基板清洗 21
3-3 氧化鋅薄膜製備 22
3-4 儀器分析 23
3-4-1 X光繞射分析儀 23
3-4-2 X光光電子能譜儀 25
3-4-3 原子力顯微鏡 27
3-4-4 導電力顯微鏡 31
第四章 結果與討論 32
4-1 XRD結果 32
4-2 AFM結果 37
4-3 CAFM結果 43
4-4 XPS結果 49
4-5 導電性討論 59
4-5-1 結晶度之影響 59
4-5-2 晶體顆粒大小之影響 60
4-5-3 元素配比之影響 60
第五章 結論 64
參考文獻 66
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