利用銅膜和氧化鋁(Al2O3)基板直接反應生成CuAlO2薄膜的研究

Abstract

透明導電氧化物(TCO)對於半導體業界來說，是相當具有未來發展潛力的材料，但由於氧化物結構的關係，大部分透明導電氧化物(TCO)的研究都屬於n型，p型透明導電氧化物(TCO)的研究成果並不豐富。 我們所要研究的CuAlO2，就是屬於p型透明導電氧化物(TCO)，從目前有關CuAlO2的研究中，發現不管是以何種方法製作，對於靶材的製作或要求都有當繁複的步驟，且做出的CuAlO2薄膜大都是屬於多晶的結構，電阻率0.01Ω-cm ~ 10Ω-cm，可見光的穿透率50％ ~ 80％；因此，我們想以一個簡易的方法來製作CuAlO2薄膜，希望能得到單晶的結構、提高可見光的穿透率和降低電阻率。 我們利用在氧化鋁(001)基板濺鍍一層銅膜的方法來製作CuAlO2薄膜。濺鍍的氬氣分壓大約是60 mtorr，基板溫度300K~600K；之後把樣品置於高温且含氧的環境下作加熱，加熱溫度>1000K左右，而氧氣的分壓100~760torr。 我們將生長好的樣品利用X光晶格繞射的方法來檢驗，發現樣品的繞射圖形確實與CuAlO2的晶格結構吻合，且是單晶結構。

Transparent conducting oxide (TCO) materials have great potential for the semiconductor industry, such as light emitting devices or solar cells. Because of the general characteristic in the electronic structure of oxides, there are few studies about p-type TCO’s. CuAlO2 is one of the p-type TCO materials. From other studies, most methods of making CuAlO2 thin films needed mixed target or more than one targets. The films’ properties are 0.01 Ω-cm~10 Ω-cm in resistivity, 50％ ~ 80％ of visible light transmittance, and poly-crystalline. Our goal is to synthesize single crystalline CuAlO2 thin films with high visible transmittance, and low resistivity by a simple synthetic route. Transparent conducting thin films of CuAlO2 were prepared by RF sputtering of a pure copper target on c-face sapphire substrates. The sputtering was performed in ~ 60 mtorr of Ar atmosphere and the substrate temperature was in the range of 300 K to 600 K. After deposition, the substrate temperature was raised to above 1000 K and the films were annealed in O2 atmosphere (100 ~ 760 torr). The X-ray diffraction (XRD) patterns of the films showed the peaks which could be assigned with those of the crystalline CuAlO2, and the structure is single crystalline.