氧化鋅/硫化鋅核殼奈米結構之製備與特性分析

Abstract

本論文使用微波輔助合成技術製備硫化鋅奈米球體、氧化鋅奈米柱與具陣列形貌的氧化鋅/硫化鋅核殼結構。我們先使用硫代乙醯胺分別與硫酸鋅和硝酸鋅作為前驅物，合成出硫化鋅奈米球體。再使用六亞甲基四胺個別與硫酸鋅和硝酸鋅反應，能分別合成出氧化鋅奈米柱與片狀結構。最後，我們先在矽基板上成長氧化鋅奈米柱陣列，再與硫代乙醯胺進行反應，成功製備出氧化鋅/硫化鋅核殼結構。我們進一步使用X光繞射光譜、掃描式電子顯微鏡與光激螢光光譜等實驗討論所製備氧化鋅/硫化鋅核殼結構的結構與光學特性。 由X光繞射光譜可以發現氧化鋅/硫化鋅核殼結構會清楚呈現出屬於氧化鋅(002)的繞射訊號，隨著增加硫代乙醯胺的莫耳濃度，屬於硫化鋅(111)繞射峰訊號強度也會逐漸增加。由掃描式電子顯微鏡的結果，可以發現氧化鋅奈米柱核體會隨著硫代乙醯胺的莫耳濃度增加而變細且變短，而硫化鋅殼體的顆粒則會逐漸變大。由低溫光激螢光光譜圖中，可以觀察到氧化鋅/硫化鋅核殼結構的發光位置約為3.33 eV，是屬於氧化鋅的近帶能隙的放光機制。

關鍵詞：微波輔助合成、硫化鋅、氧化鋅、核殼結構

In this thesis, the zinc sulfide (ZnS) nanoball, zinc oxide (ZnO) nanorod and well-arrayed ZnO/ZnS core-shell structure were fabricated successfully by microwave-assisted heating. The ZnS nanoball can be prepared by using the hexamethylene triamine (HMT) with Zn(NO3)2‧6H2O) and (ZnSO4‧7H2O) as the precursors. The ZnO nanorod and nanosheet were synthesized by using the Thioacetamide (TAA) with Zn(NO3)2‧6H2O) and (ZnSO4‧7H2O), respectively. The well-arrayed ZnO nanorods grown on Si substrate were further interacted with TAA to form the ZnO/ZnS core-shell structure. We investigated the structure and optical properties of the ZnO/ZnS core-shell structure by X-ray diffraction (XRD), scanning electron microscope (SEM), and photoluminescence (PL) measurements. The XRD results indicated that the ZnO/ZnS core-shell structure can showed a significant ZnO (002) peak belonging to ZnO as well as a weak (111) peak from ZnS. It is noted that the (111) peak can be enhanced with increasing the molar ratio of TAA. SEM images show that the ZnO nanorod would be narrower and shorter but the ZnS would be larger as a function of the molar ratio of TAA. It is observed that the 12 K PL spectra of the ZnO/ZnS core-shell structure locate at about 3.33 eV, which can be attributed to the near-band-edge (NBE) of ZnO.

Keywords: Microwave-assisted heating, ZnS, ZnO, core-shell structure