Fabrications and Electro-Optical Properties of P-Type ZnO Films 彭子安、王立民
E-mail: [email protected]
ABSTRACT
In this work, the p-type N-Al co-doped ZnO films were deposited at room temperature on corning glass substrates by magnetron radio frequency (RF) sputtering. We studied the influences of crystalline orientation, surface morphology and doping concentration on the conductivity、carrier concentration、mobility、transmittance and photoluminescence. We realized controllable growth of n-type and p-type Al-N co-doped ZnO thin films by adiusting the radio frequency power, reducing intrinsic defects, and activating N-related acceptors.The sputtering parameters were adjusted and employed to obtain the optimum electro-optical properties of ZnO:(Al, N) thin film.
The optimum conditions for the growth of 400-nm ZnO:(N, Al) films are set with ZnO:Al RF power = 230 W and working pressure
= 10 mTorr. The postannealing temperature was fixed in 550 oC for 30 min under nitrogen ambient. As a result, we achieve a lowest resistivity with value of 1.6 Ωcm, carrier concentration of 2.3×1016 m-3 and mobility of 165 cm2/Vs. The average optical transmittance within the visible spectra is more than 80 %. It is found that the ZnO:(Al, N) films with Al/Zn of 10~20 at.% and N/Al of 1~1.3 reveal a p-type character conduction, approaching to the theoretical calculation 2:1.It is also found that the main defects of p-type ZnO:(Al, N) are combined with Zinc vacancies (Vzn) and oxygen vacancies (Vo), possibly leading to the formation of the bonds Al-N by the substitution of Al for of Zn atoms and the substitution of N for O atoms, which may result in p-type conduction in Al-N co-doped ZnO thin films.
Keywords : ZnO、RF magnetron sputtering、resistivity、doping
Table of Contents
封面內頁 簽名頁
授權書．．．．．．．．．．．．．．．．．．．．．．．．．iii 中文摘要．．．．．．．．．．．．．．．．．．．．．．．．iv 英文摘要．．．．．．．．．．．．．．．．．．．．．．．．v 誌謝．．．．．．．．．．．．．．．．．．．．．．．．．．vi 目錄．．．．．．．．．．．．．．．．．．．．．．．．．．vii 圖目錄．．．．．．．．．．．．．．．．．．．．．．．．．x 表目錄．．．．．．．．．．．．．．．．．．．．．．．．．xiv
第一章 緒論
1.1 前言與研究目的．．．．．．．．．．．．．．．1 1.2 氧化鋅薄膜(zinc oxide thin films，ZnO)的介紹．．．3 1.2.1 光電性質．．．．．．．．．．．．．．．．4 1.3 p型導電氧化鋅的研究現況．．．．．．．．．．．7
第二章 實驗方法與步驟
2.1 實驗流程．．．．．．．．．．．．．．．．．．12 2.2 實驗材料．．．．．．．．．．．．．．．．．．14 2.2.1 靶材．．．．．．．．．．．．．．．．．．14 2.2.2 基材．．．．．．．．．．．．．．．．．．14 2.3 實驗裝置．．．．．．．．．．．．．．．．．．15 2.4 鍍膜??及步驟．．．．．．．．．．．．．．．17 2.4.1 鍍膜??．．．．．．．．．．．．．．．．17 2.4.2 基座清洗．．．．．．．．．．．．．．．．18 2.4.3 沉積 ZnO:(N, Al)薄膜 ．．．．．．．．．．19
2.5 薄膜性質測試與應用分析．．．．．．．．．．．20 2.5.1 X-Ray繞射研究．．．．．．．．．．．．．20 2.5.2 原子力顯微鏡(AFM)圖像之分析．．．．．．21 2.5.3 霍爾效應量測(Hall-Effect)．．．．．．．．．22 2.5.4 光穿透率量測 (UV-visible Spectrometer)．．．25 2.5.5 光激螢光發光量測 (Photoluminescence, PL)． 26
2.5.6 X射線能量散佈分析儀 (Energy Dispersive Spectrometer, EDS)．．．．．．．．．．．．．． 27 2.5.7 半導體的傳輸機制．．．．．．．．．．．． 29
第三章 結果與討論
3.1 ZnO:(N, Al)薄膜結構與組成之研究．．．．．．． 31 3.1.1 製成參數對薄膜結構造成的影響．．．．．．32 3.1.2 製成參數對表面形貌造成的影響．．．．．．45 3.1.3 製成參數對原子組成造成的影響．．．．．．76 3.2 製程參數對ZnO:(N, Al)薄膜光電特性之影響．．． 84 3.2.1 氮氣分壓之影響．．．．．．．．．．．．84 3.2.2 射頻功率之影響．．．．．．．．．．．．90 3.2.3 工作壓力之影響．．．．．．．．．．．．95 3.2.4 基板溫度之影響．．．．．．．．．．．．101 3.3 p型ZnO最佳條件之探討．．．．．．．．．． 106 3.3.1 氮氣分壓之影響．．．．．．．．．．．．．106 3.3.2 射頻功率之影響．．．．．．．．．．．．．112 3.3.3 工作壓力之影響．．．．．．．．．．．．．117 3.3.4 基板溫度之影響 ．．．．．．．．．．．．122 3.4 傳輸機制之探討．．．．．．．．．．．．．．．127
第四章 結論．．．．．．．．．．．．．．．．．．．．．．133 參考文獻．．．．．．．．．．．．．．．．．．．．．．．． 135 REFERENCES
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