用熱氣相沉積法成選擇性成長氧化鋅奈米線

Abstract

我們成功的利用熱氣相沉積法在不同的基板溫度下成長不同型態的氧化鋅奈米線的結構。先將基板加熱到指定的溫度再將鋅的來源推入爐管內，這樣的方法能有效的得到較單一形態的氧化鋅奈米結構。換句話說，利用預熱的方式能夠有效的降低氧化鋅緩衝層的厚度。我們的系統在特定的溫度下所成長出來的氧化鋅奈米線會有最小的緩衝層，並且大部分的奈米線都是垂直基板成長，較低溫的基板溫度下所成長的氧化鋅奈米線會有傾斜的現象產生，並且在X光繞射下有發現(101)面的訊號。我們可以利用基板的對稱性與不同溫度下緩衝層的結晶性來解釋，單單利用預熱基板的方式即有效降低緩衝層，這樣能使熱氣相沉積法所成長出來的氧化鋅奈米線在元件應用上更具有優勢。 在氧化鋅奈米線結構研究中，我們以X光繞射，以及拉曼光譜確定其為纖鋅礦結構的氧化鋅。在室溫光激發光光譜中，能量在3.27eV附近有很強的激子復合所產生的螢光，其寬度為110 meV；並且在在低溫光激發光光譜中能觀察到許多氧化鋅在低溫系統下的螢光並且去借由公式去比照後與理論結果相符。

We have successfully demonstrated synthesis ZnO nanowires by steady-state vapor transport deposition. The morphology of ZnO nanostructures would depend on various grown temperatures of the substrate. By loading the Zn source after the substrate has reached the reaction temperature, the buffer layer can be effectively reduced. XRD and Raman measurements indicate that the ZnO nanoswires are made of the single-crystal with wurtzite structure. We also measured the PL spectra of the nanowires at room and low temperature. At room temperature, it shows that an intensive emission peak at about 3.27 eV FWHM~110 meV is attributed to the recombination of free excitons. At low temperature, we have observed bound-excitons, two-electron satellite, donor-accepter peaks, phonon replicas and calculated the activation energy for temperature dependence on PL spectra of near band edge emission that is close to the free excitons binding energy.