利用化學浴沉積法於合成n-Cu2O:Cl薄膜之特性研究

Preparation and characterization of chlorine-doped n-type cuprous oxide films by chemical bath deposition

卓訓安(Xun-An Zhuo)

指導教授 ： 籃山明

中原大學/工學院/電子工程研究所/碩士(2014年)

https://doi.org/10.6840/cycu201400553

摘要

摘要
氧化亞銅(Cu2O)具有直接能隙，能隙為2.1eV，在可見光區吸收係數大，穿透率低等特性，將其應用在太陽能電池研製上，可期望以低價位開發新型太陽能電池。合成Cu2O半導體薄膜所用的材料取得容易，銅金屬在地殼中的含量相當豐富，有著低價位、簡單、無毒的製程等優點，很合乎環保的需求。然而現今欲廣泛應用Cu2O 於太陽能電池研製的困難乃在於N型Cu2O薄膜無法取得。
本研究利用純銅片作為基板，以化學浴沉積 (Chemical Bath Deposition, CBD) 法分別於未摻雜與摻雜氯的情況下製備Cu2O薄膜。未摻雜時使用硫酸銅（CuSO4）水溶液做為成長溶液；摻雜氯時則使用氯化鈉（NaCl）與CuSO4的混和水溶液作為成長溶液，其中NaCl為摻雜源。實驗中特別改變水溶液中NaCl相對於CuSO4之莫爾濃度比(CuSO4/NaCl)以期調變控制Cu2O 薄膜中不同程度的摻雜濃度。
研究結果發現，X光繞射(XRD)分析光譜中只出現來自Cu2O晶面的繞射角度，且於成長溶液之CuSO4/NaCl = 1:0至1:3.0的條件下皆可由熱探針(hot point probe)量测證明所產生的Cu2O薄膜均為N型導電性，未摻雜Cu2O的電阻率為70Ω-cm，但當期莫爾比為1.428時，可製備出電阻率大約為48Ω-cm的N型Cu2O薄膜。低溫5K下所量測的光激螢光(PL)光譜中顯示出分別與氧空缺及氯摻雜有關的兩個發光尖峰於1.72eV及1.89eV，而並未發現與銅空缺(波長為905nm)有關的發光，推斷其原因是CBD合成N型Cu2O:Cl薄膜的溫度只在100oC左右，而使銅空缺不易形成，因銅空缺是形成P型導電性的機制。因此推斷使用銅基板可抑制銅空缺之發生，而以氯原子取代氧原子後則發揮N型雜質角色，進一步提供載子來改善電阻率。

關鍵字

氧化亞銅摻雜 ； 化學浴沉積法 ； 氧空缺

並列摘要

Abstract
Chlorine (Cl)-doped cuprous oxide (Cu2O:Cl) thin films were fabricated on copper (Cu) substrate by chemical bath deposition (CBD) method. The Cu2O:Cl films were prepared using copper sulfate (CuSO4) solution with the addition of copper chloride (NaCl) as Cl- source. The molar ratio of NaCl to CuSO4 ([NaCl]/[CuSO4]) was varied from 0 to 2.60. Resultantly, hot point probe measurements demonstrated n-type conductivity for all the Cu2O films produced by CBD. X-ray diffraction patterns show that the as-grown Cu2O:Cl films have a sphalerite structure with a dominant plane orientation of Cu2O(111). Moreover, low temperature photoluminescence (PL) measurements conducted at 5 K demonstrated an emission band at 1.89 eV related to Cl doping besides that at 1.72 eV attributed to doubly ionized oxygen vacancies. It was found that the Cl-related PL emission was intensified with increasing the amount of Cl involved. But X-ray photoelectron spectroscopy not confirmed the incorporation of Cl into the lattice of Cu2O. Conclusively, n-type Cu2O:Cl films with the resistivity ranging from 40 – 50 -cm can be produced on Cu substrate by CBD method. Especially, the lowest resistence of the film is about 48Ω-cm under the ([NaCl]/[CuSO4]) ratio equal to1.428. The doped part, chlorine can be successfully incorporation into cuprous oxide, and replace the oxygen atom to the N-type electrically.

並列關鍵字

chemical bath deposition ； Chlorine-doped n-type cuprous oxide films ； oxygen vacancies

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