具氧化鋅奈米柱之發光二極體製作
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2010
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發光二極體被視為未來主要的照明光源，高功率發光二極體於技術上屢有突破，但現階段發光效率的不足，使發光二極體無法取代傳統光源作為照明燈源的主流，故發光二極體發光效率的提升，是目前技術發展的重點之一。過去的研究指出，將奈米線應用於發光二極體的結構製作，能有效提升其發光強度；而在各式成長奈米線的方法中，水熱法製備之奈米線具有高品質順向成長與製程簡易的優點，故本論文將採用此法成長氧化鋅奈米線，並以射頻濺鍍法沉積N型氧化鋅鋁薄膜，P型材料則選用氧化鋅與氮化鎵薄膜結構，藉以製備其氧化鋅奈米線之發光二極體，並進行其發光特性之研究。
在奈米線的部份，藉由水熱法成功製備氧化鋅奈米線，氧化鋅奈米線摻雜鋁部分，鑑於製程步驟與參數和文獻有所不同，故摻雜效果不彰，需以更多的參數進行測試。熱處理氧化鋅奈米線方面，可發現因缺陷產生的綠光波段強度明顯降低，並且對於降低阻值與能障有很大幫助。
P型氧化鋅部份，使用摻雜P2O5氧化鋅靶材，在具有氧化鋅緩衝層之藍寶石基板上，加熱至700 C，藉由氬/氧流量比例為1:3，沉積氧化鋅磷薄膜，並在氧氣的氣氛下冷卻。隨後氧化鋅磷薄膜經由RTA處理，有可能製備出P型氧化鋅薄膜。目前在RTA持溫溫度900 C，持溫5分鐘之處理下，已製備出局部P型氧化鋅薄膜，其載子濃度為8.7921018 cm-3，移動率為0.793 cm2 / V-s，電阻率為0.8953 -cm。實驗的結果推測可能是試片電性轉換不完全所致。未來將考慮以共濺鍍或熱擴散的方式，繼續P型氧化鋅薄膜之試驗。
發光二極體部份，目前已於P型氮化鎵(鎂摻雜，載子濃度約為1017 cm-3)薄膜上，成功製備氧化鋅奈米線/N型氧化鋅鋁薄膜結構，並完成發光二極體之晶粒製作，其尺寸為300 m 300 m。在約大於15 V的操作電壓下，以長工作距離顯微鏡可觀察到，發光二極體晶粒的部份區域放射出藍光，且發光強度隨著電壓增加而變大。但初期製作之串聯電阻極高，且電流分布不均，在改善電極形狀後，可以有效增加電流分布的範圍，並且經過製程順序的調整，能有效改善因快速熱退火處理對鋁電極產生的不良影響，讓發光區域增加。未來將以快速熱退火進行後處理，並檢測其電極是否形成歐姆接觸，以期提升性能，進而檢測其發光頻譜等特性。
Light emitting diode (LED) is considered as the major next-generation luminescence technology, but nowadays insufficient light efficiency of high power LED limits its application for illumination lighting. Some research group have developed nanowrie-inserted LED structure, and the EL intensity shows that the novel LED structure can improve light efficiency effectively. ZnO nanowires grown by hydrothermal method have excellent properties such as single crystal, vertical alignment, broad area growth and simple process. Thus in this study hydrothermal method is adopted to fabricate ZnO nanowires, N-type material of LED is aluminum-doped ZnO film (AZO) deposited by RF sputtering, and P-type materials are ZnO and Mg-doped GaN film. Finally, the characteristics of N-type AZO/ZnO nanowire/P-type ZnO or P-type GaN structure LED will be studied. The ZnO nanowries grown by hydrothermal method are successful. The outcomes of Al doped ZnO nanowires are not well because the method was different to references. It needs to try more parameters. The thermal treatment of ZnO nanowires can reduce the green light emission which cause by defects. It’s effect on reducing resistance and energy barrier. P2O5 doped ZnO targets are used to deposit P-type ZnO film by O2/Ar flow rate is 3. Using sapphire with ZnO buffer layer, heating to 700 C, cooling with O2 ambiance after ZnO deposited, following by RTA treatment, might produce the p-type ZnO film. The as-grown film then treated follow by rapid thermal annealing at 900 C for 5 minutes had produced to partial p-type ZnO film. The carrier concentration is 8.7921018 cm-3. The mobility is 0.793 cm2 / V-s. The resistivity is 0.8953 -cm. The result might be the electric property transformed incompletely. The co-sputter technique will be used to fabricated P-type ZnO film continuously. For LED study, ZnO nanowrie/N-type AZO film have been fabricated on Mg-doped P-GaN film (carrier concentration is about 1017 cm-3), the size of LED die is 300 m 300 m. Blue emission is observed from partial area of LED die through long-distance microscope when forward-bias is above 15 V, and voltage raise leads to increasing of light intensity. After changing the electrode’s shape, it can improve the current distribution of LED to increase the lighting area. In the next step, current-voltage relation and electroluminescence (EL) spectrum will be examined.
Light emitting diode (LED) is considered as the major next-generation luminescence technology, but nowadays insufficient light efficiency of high power LED limits its application for illumination lighting. Some research group have developed nanowrie-inserted LED structure, and the EL intensity shows that the novel LED structure can improve light efficiency effectively. ZnO nanowires grown by hydrothermal method have excellent properties such as single crystal, vertical alignment, broad area growth and simple process. Thus in this study hydrothermal method is adopted to fabricate ZnO nanowires, N-type material of LED is aluminum-doped ZnO film (AZO) deposited by RF sputtering, and P-type materials are ZnO and Mg-doped GaN film. Finally, the characteristics of N-type AZO/ZnO nanowire/P-type ZnO or P-type GaN structure LED will be studied. The ZnO nanowries grown by hydrothermal method are successful. The outcomes of Al doped ZnO nanowires are not well because the method was different to references. It needs to try more parameters. The thermal treatment of ZnO nanowires can reduce the green light emission which cause by defects. It’s effect on reducing resistance and energy barrier. P2O5 doped ZnO targets are used to deposit P-type ZnO film by O2/Ar flow rate is 3. Using sapphire with ZnO buffer layer, heating to 700 C, cooling with O2 ambiance after ZnO deposited, following by RTA treatment, might produce the p-type ZnO film. The as-grown film then treated follow by rapid thermal annealing at 900 C for 5 minutes had produced to partial p-type ZnO film. The carrier concentration is 8.7921018 cm-3. The mobility is 0.793 cm2 / V-s. The resistivity is 0.8953 -cm. The result might be the electric property transformed incompletely. The co-sputter technique will be used to fabricated P-type ZnO film continuously. For LED study, ZnO nanowrie/N-type AZO film have been fabricated on Mg-doped P-GaN film (carrier concentration is about 1017 cm-3), the size of LED die is 300 m 300 m. Blue emission is observed from partial area of LED die through long-distance microscope when forward-bias is above 15 V, and voltage raise leads to increasing of light intensity. After changing the electrode’s shape, it can improve the current distribution of LED to increase the lighting area. In the next step, current-voltage relation and electroluminescence (EL) spectrum will be examined.
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Keywords
氧化鋅奈米線, 發光二極體, 水熱法, P型氮化鎵, P型氧化鋅, ZnO nanowrie, light-emitting diode, hydrothermal method, P-GaN, P-ZnO