斜向濺鍍氧化鋅於氮化鎵奈米柱陣列之新穎紫外光二極體研究

Abstract

本論文是以磁控濺鍍系統斜向成長 n 型氧化鋅於 p 型氮化鎵二維奈米柱陣列結構，來製作具高載子注入效率與高輻射複合率之氧化鋅/氮化鎵異質接面紫外光發光二極體奈米柱陣列(ZnO/GaN nanorod array LEDs)。藉由氮化鎵奈米柱本身所提供的遮蔽效應(shadowing effect)，斜向氧化鋅濺鍍氣流(glancing ZnO vapor-flows)將選擇性的沉積於氮化鎵奈米柱陣列頂端，並有效地連結整個二維氮化鎵奈米柱，最終形成具奈米尺寸的異質接面(nano-junctions)發光二極體陣列。我們所製作出之氧化鋅/氮化鎵異質接面紫外光發光二極體奈米柱陣列本身具有良好的二極體整流特性和低導通電壓(4.5V)，並在順向電流的操作下可穩定發射主要波長為 λ＝390nm 之偏紫白光發光光譜。其主要可歸因於奈米異質接面結構之高載子注入效率所造成氧化鋅缺陷複合飽和，以及氧化鋅近能隙複合發光效率之提升。更重要的是，本論文所提出的斜向濺鍍氧化鋅方法將可省去在傳統奈米柱結構之鈍化與絕緣過程中，所需涉及聚合物填充或其他複雜之材料生長步驟，大幅地提升元件良率與降低製作成本，並可廣泛地運用於其他具奈米尺寸之光電元件(nano-devices)。

High-efficient ZnO-based nanorod array light-emitting diodes (LEDs) were grown by an oblique-angle deposition scheme. Due to the shadowing effect, the inclined ZnO vapor-flow was selectively deposited on the tip surfaces of pre-fabricated p-GaN nanorod arrays, resulting in the formation of nanosized heterojunctions. The LED architecture composed of the slanted n-ZnO film on p-GaN nanorod arrays exhibits a well-behaving current rectification of junction diode with low turn-on voltage of 4.5 V, and stably emits violetish-white luminescence with dominant peak of 390 nm under the operation of forward injection currents. In general, as the device fabrication does not involve passivation of using a polymer or sophisticated material growth techniques, the revealed scheme might be readily applied on other kinds of nanoscale optoelectronic devices.