A study on the fabrication of ZnO nanowire/CuO coaxial heterojunction and its optical properties

同軸半導體異質接面近年來引起大家廣泛的研究。由於此結構具有較高的面積-體積比、良好的光捕捉能力以及分離電子和電洞的能力。這些優點使他們成為製作光電元件結構的最佳選擇。 在此，我們報告用改良的方法製作氧化鋅/氧化銅同軸異質接面奈米線陣列。首先，氧化鋅奈米線是利用水熱法成長在鍍有氧化銦錫的玻璃基板上，接著在氧化鋅奈米線陣列上塗上一層光阻，再利用丙酮將氧化鋅奈米線頂部的光阻去除但底部的光阻仍然蓋住氧化鋅緩衝層。最後利用電化學沉積法鍍上銅在氧化鋅奈米線上，最後將樣品送入高溫爐加熱並通入氧氣形成氧化銅。 SEM, XRD顯示了氧化鋅/氧化銅同軸異質接面奈米線陣列具有良好的晶體結構。穿透光譜、電壓-電流量測以及光反應皆顯示了氧化鋅/氧化銅同軸異質結構奈米線陣列具有良好的電學和光學性質。此結構在+3 V至-3 V的整流率為110，在-3 V的漏電流為-12.6 uA。 這些結果顯示加入光阻絕緣層的氧化鋅/氧化銅同軸異質接面奈米線陣列具有好的晶格結構以及良好的光電性質，所以氧化鋅/氧化銅同軸異質結構奈米線陣列可以當一個良好的紫外光光偵測器。Type-II semiconductor coaxial heterojunction has attracted much attention recently. The high surface-to-volume ratio, good light trapping ability and spatially separated charge carriers in these nanostructures made them a potential candidate for high efficient optoelectronic devices. In this thesis, we showed that an enhanced photo-response near the violet range can be obtained for the ZnO/CuO coaxial heterojunction structure grown by hydro-thermal method. The results from SEM, XRD, TEM, and transmission spectroscopy used to study the structural and optical characteristics of ZnO/CuO coaxial heterojunction indicated a good crystalline quality Spin-coating of a layer of photoresist before electrochemically depositing the CuO layer on top of the ZnO nanowires proved to be important in improving the photo response of the ZnO/CuO heterojunction as the photoresist acts as an insulating layer and can reduce the leakage current in these structures quite substantially. The optical measurement showed that ZnO/CuO coaxial structure prepared with our method has good rectifying ratio, small reverse leakage current and has good photo responsivity in the ultra-violet range of the light spectrum. The results demonstrated that cost-effective and simple fabrication of the good ZnO/CuO coaxial heterojunction photo detector can be prepared by using a cost-effective way with a simple fabrication scheme