國立台灣大學林清富教授實驗室
研究領域摘要
主題四: 氧化鋅奈米結構及其應用
研究人員: 黃敬舜、李俊育、蘇文彥、周貞佑
英文摘要:
One-dimensional (1D) nanowires have been extensively studied in recent years. Among these materials, zinc oxide (ZnO) nanowires have attracted great interest
for promising applications in optoelectronics devices such as room temperature lasers, light emitting diodes, ultraviolet (UV) detectors, field emission displays,
photonic crystals, and solar cells. ZnO is a wide band gap (3.37 eV) semiconductor with a large exciton binding energy (60meV), exhibiting near-UV light
emission, transparent conductivity, and piezoelectricity. Several methods have been demonstrated to fabricate 1D ZnO nanostructures, such as vapor-liquid-
solid epitaxy (VLSE), chemical vapor deposition (CVD), and pulse laser deposition (PLD), but these gas phase techniques still have some limitations for
substrate size and the need for high temperature operation (above 800 ℃ for VLSE and 500 ℃ for CVD method). Recently, growth of ZnO nanowires and
microrods in aqueous solutions at low temperature was reported by using the hydrothermal process. Hydrothermal process has shown the possibility for
applications in light emitting diodes and solar cells with their growth temperature below 100 ℃ and easy scale-up. This aqueous-based technique has also been
used successfully to demonstrate the fabrication of large arrays of vertical ZnO nanowires on glass, 4-in. diameter Si wafers, and plastic substrates. This
stimulated the study of using ZnO nanowire arrays on plastic substrates for application in flexible electronic devices. However, these device applications might
be reinforced if the position, orientation, and shape of nanostructures can be controlled to a high degree of precision.
This work provides a systematic study of feature-controlled ZnO nanowire arrays via hydrothermal method. Our investigation demonstrates that the sol-gel thin-
film pretreatment conditions have strong influences on the features of the ZnO nanowire arrays grown thereon. The annealing temperature of the ZnO sol-gel
thin film can affect the microstructure of the ZnO grains and then the growth of the ZnO nanowire arrays. As the annealing temperature increases from 130 to
900 ℃, the grain size of the thin films increases, and the diameter of thereon ZnO nanowire arrays increases from 60 to 260 nm. The thin films influence the
nucleation of the ZnO and subsequently affect the diameter and orientation of the thereon nanowire arrays. At the temperature of 130 ℃, the ZnO nanowire
arrays align very vertically with growth along the c-axis direction. The PL measurements show a strong UV emission at 385nm, indicating that the low-
temperature growth results in low levels of oxygen vacancies in the nanowires. This work provides all solution-based processing routes to fabrication of low-
cost highly oriented ZnO nanowire arrays at low temperature. These vertical nanowire arrays are highly suitable for use in ordered nanowire-polymer devices,
such as solar cells and light emitting diodes.
Figure 1 SEM images of ZnO sol-gel thin films with annealing at (a)130℃, (c)300℃, (e)600℃, and (g)900℃. (b), (d), (f), and (h) show the ZnO nanowire
arrays were grown at a fixed temperature (90 ℃), while the thin films were annealed at 130, 300, 600, 900 ℃, respectively.
Figure 2 XRD spectra of (a) ZnO seed layers annealed from 130 to 900℃, and (b) thereon ZnO nanowire arrays.
Figure 3 EDS spectra of ZnO nanowire arrays with ZnO seed layers annealed from 130 to 900℃.
Figure 4 Room temperature PL spectra of (a)ZnO seed layers and (b)thereon ZnO nanowire arrays with annealing temperature of ZnO seed layers from 130 to 900℃ for 1 hour in air (excitation wavelength: 266nm)
中文摘要：
氧化鋅奈米線近年來被廣泛應用於光電元件中，如紫外光雷射、紫外光 LED、紫外光偵測器、氣體感測器、場發射顯示器以及太陽能電池等。
水熱法(Hydrothermal method)是眾多製備氧化鋅奈米線方法中最便宜且可大量製造的方法，然而如何控制氧化鋅奈米線的生長卻是一項重要的課
題。我們利用這個方法可成功製作出方向性一致且單晶的氧化鋅奈米線，並使用場發射顯微鏡(FESEM)、能量散佈光譜(EDS)、X 光繞射(XRD)與
光激發光光譜(PL)來分析氧化鋅奈米線的表面形貌、材料以及光學特性。我們發現氧化晶種層的特性在奈米線的成長過程中扮演相當重要的角色
，經由晶種層的前置處理我們可以改變氧化鋅晶粒的微結構進而有效地控制氧化鋅奈米線的粗細與方向性，此結果對光電元件與奈米元件的應
用將有相當大的助益。
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