奈米線體積微小使閘極降低短通道效應而更為有效控制通道，發展出高性能場效電晶體之應用等，氮化鋁作為功能性陶瓷及寬能隙半導體具有許多應用價值，其製作方法很多，品質也有差異。本研究主要探討兩種製作氮化鋁奈米線的製程方法並討論其生成氮化鋁奈米線的差異，第一種是使用靜電紡絲法得到奈米纖維並進行碳熱還原氮化反應氮化鋁奈米線，第二種是使用金屬催化劑輔助化學氣相沉積藉由氣液固成長機制成長氮化鋁奈米線。
靜電紡絲法具有設備簡易、成本低、可大量製造等優點；前驅物溶液配製選擇聚乙烯吡咯烷酮(Polyvinylpyrrolidone, PVP)，硝酸鋁做為鋁源，在不同濃度或是不同電壓下其實驗結果以12.6 wt% PVP溶液於電壓20 kV收集距離10 cm下靜電紡絲之前軀物纖維，平均直徑為252 nm，前軀物纖維進行碳熱還原氮化合成奈米線，在X-Ray及拉曼光譜峰值顯示產物為純氮化鋁，進一步以TGA/DSC結果分析在升溫曲線中增加1200℃持溫，再升溫至1500℃其氮化鋁奈米線平均直徑從252 nm下降至131 nm且外觀光滑。以濺鍍機不同電流秒數在藍寶石基板鍍上一層不同厚度的金膜及做為鋁源的鋁粉與基板間距不同下，在氨氣環境下升溫到1200℃進行化學氣相反應成長氮化鋁奈米線；實驗結果顯示催化層厚度以鍍膜係數10mA10s在基板鍍上一層金，鋁粉與藍寶石間距4.8 mm在氨氣環境下進行化學氣相沉積成長奈米線不僅茂密且平均直徑136 nm為最佳，拉曼及X-Ray繞射中晶格特徵峰較明顯，也符合六方晶系纖鋅礦結構的氮化鋁晶格方向。
兩種製程的氮化鋁奈米線進行比較，碳熱還原氮化合成氮化鋁奈米線平均直徑(131 nm)跟化學氣相沉積平均直徑(136 nm)且兩製程的奈米線平均直徑皆在150 nm以下且長度可達數微米，但直徑分布範圍以碳熱還原氮化合成之奈米線較小。在X-Ray及拉曼光譜峰值顯示產物為純氮化鋁，在X-Ray圖化學氣相沉積製程的奈米線(002)方向特徵峰強烈，碳熱還原氮化製程峰值傾向於多晶結構。
The application of high-performance field-effect transistor has been developed. Recently, the nanowire semiconductor devices, which enable to reduce the gate short-channel effect and control the channel current effectively, have brought a wide interest. Aluminum nitride has many applications as a functional ceramic and wide-bandgap semiconductor. There are many methods for the growth of AlN nanowires have been reported but differences in the nanowire quality. This research investigates two synthesis methods for the growth and characteristics of AlN nanowires. The first is to use electrospinning to obtain nanofibers and perform carbothermal reduction and nitridation reactions. The second is to use metal catalysts to assist chemical vapor deposition to grow AlN nanowires through a gas-liquid-solid growth mechanism.
The method of electrospinning has the advantages of simple equipment, low cost, and large-scale manufacturing. In this experiment, the precursor solution was prepared by polyvinylpyrrolidone (PVP) and aluminum nitrate as the aluminum source. Based on different concentrations or voltages, an average diameter of the precursor fibers was obtained of 252 nm by 12.6 wt% PVP solution electrospinned at 20 kV. The precursor fibers were subjected to carbothermal reduction and nitridation to synthesize nanowires afterwards. The results showed that the average diameter of AlN nanowires with smooth appearance was reduced to 131 nm by a two stage heating of temperature 1200℃ and 1500℃. In CVD method layer of gold film of different thickness is deposited on the sapphire substrate as catalyst. The temperature is raised to 1200℃ in the presence of ammonia for chemical vapor deposition to grow AlN nanowires. Experimental results show that the AlN nanowires with hexagonal wurtzite structure in the average diameter of 136 nm were obtained.
The average diameter of AlN nanowires grown by both methods were all below 150 nm and the length can reach several microns, but the diameter distribution range of nanowires synthesized by carbothermal reduction and nitridation is relatively small. The X-Ray and Raman spectrum peaks show that the product is pure aluminum nitride. The XRD characteristic peak (002) of the nanowire grown by chemical vapor deposition process is strong, and the peak of the carbothermal reduction and nitridation process tends to be polycrystalline structure.
