陽離子、陰離子與陰陽離子共摻雜對於p型氧化錫薄膜之電性之影響研究與陽離子空缺誘導模型建立

Doping of cation, anion, and cation-anion co-doping in the p-type SnO2 thin films and the construction of the induced cation vacancy model

劉晏碩(Yen-Shuo Liu)

指導教授 ： 劉正毓

國立中央大學/工學院/化學工程與材料工程學系/博士(2014年)

摘要

此篇論文研究之目的為探討各種陽離子與陰離子摻雜對於p型氧化錫的自由電洞之貢獻。藉由摻雜鋁、氮與氮化鋁於氧化錫薄膜中來探討陽離子、陰離子與陰陽離子共摻雜之影響。由實驗得知，將低摻雜比例的鋁摻雜於氧化錫中無法有效貢獻自由電洞，而氮摻雜與氮化鋁摻雜則可成功使氧化錫由n型轉換成p型半導體。藉由光電子能譜儀XPS分析，本研究可得知氮離子取代氧離子貢獻電洞為形成p型氧化錫之主要原因。然而，由於氮離子於氧化錫中呈現不穩定之狀態，造成氮離子摻雜濃度無法有效提升。且氮離子在氧化錫薄膜中會逐漸逸散(outgassing)，放置於大氣中會因氮離子的逸散使p型氧化錫逐漸轉換為n型。而本研究發現藉由共摻雜鋁，氮離子在氧化錫中的溶解度與穩定性可得到有效提升。
對於鋁離子摻雜之氧化錫薄膜導電機制，本研究大幅提高鋁摻雜於氧化錫薄膜之濃度，本研究得知(1)僅有高濃度鋁摻雜能達成p型氧化錫；(2)藉由較高的氧分壓下進行熱退火來降低氧空缺反而會降低自由電洞的生成；(3)於高溫熱處理造成氧化錫結晶相的生成為達成p型氧化錫必要的條件。除了傳統陽離子取代以提供電洞之機制外，本研究提出氧空缺會吸引取代錫之鋁離子，進而產生局部極化並誘導錫空缺生成。此外，本研究推測僅有價電子為三價之陽離子作異質摻雜能有效誘導錫空缺生成，於文獻蒐集之結果中得知此機制適用於所有藉由陽離子摻雜而達成之p型氧化錫。

關鍵字

p-type transparent conductive SnO2 ； cation doping ； anion doping ； induced cation vacancy ； XPS

並列摘要

In this study, the variety of cation and anion doped p-type SnO2 were discussed. In chapter 1, according to the literatures, the cation dopants show the poor efficiency for contributing the p-type conduction. Even though the anion (N) dopants have a higher doping efficiency compared to the cation dopants, the unstable chemical properties cause N atoms difficult to retain in SnO2 phase. In chapter 2, the electrical properties of transparent Al-doped SnO2, N-doped SnO2, and AlN-doped SnO2 thin films were studied. The N-doped SnO2 and AlN-doped SnO2 thin films demonstrated the p-type conduction with proper thermal annealing. XPS analysis verified the substituted N3- ions in the O ion sites in the annealed N-doped SnO2 and AlN-doped SnO2 thin films, which is responsible for the n-to-p conduction transition of the N-doped SnO2 and AlN-doped SnO2 thin films. However, the substituted N3- ions in the p-type N-doped SnO2 thin films outgas easily and the p-to-n conduction transition would occur in the high temperature annealing. With Al doping in the AlN-doped SnO2 thin films, a significant improvement in the stability of the substituted N3- ions was observed, which is caused by the formation Sn-N-Al bond improves the stability of the substituted N3- ions in the AlN-doped SnO2 thin films.
In chapter 3, the Al-doped SnO2 thin films were used to study the source of p-type conduction by cation doping. Three findings; (1) the p-type conduction for Al-doped SnO2 only achieved with extremely high Al concentration, (2) the decreasing oxygen vacancy concentration limits the p-type conduction, (3) the crystallity of the Al-doped SnO2 at high annealing temperature is a necessary factor for the p-type conduction. The induced cation vacancy model was proposed to explain the hole source for the high cation-doped p-type SnO2, which is adopted for all the cation-doped p-type SnO2 reported in the literatures. The results showed that only trivalence-charge cation can have a higher doping efficiency for p-type SnO2.

並列關鍵字

p型透明氧化錫 ； 陽離子摻雜 ； 陰離子摻雜 ； 陽離子空缺誘導 ； XPS光電子能譜儀

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