ITO及Ni-NiO核殼奈米柱界面之光電特性研究

Abstract

近年來，奈米元件如奈米線、奈米帶、奈米柱因提供了一維(1D)的研究平台已吸引眾多的學者做其物理性質的研究，而在一維(1D)奈米尺寸的材料中，界面是決定電性與光電反應的關鍵。 此研究利用簡便的陽極氧化鋁製程、無鍍鎳以及退火製造出一維(1D)奈米柱，展現出顯著的紫外光感測能力。首先，利用陽極氧化鋁製程及無電鍍鎳長出排列整齊的鎳柱(核)，之後在350°C氧氧環境下退火15和30分鐘在鎳柱外長出一層氧化鎳(殼)，氧化鎳的厚度可經由退火時間控制，在350°C氧氧環境下退火15和30分鐘分別可長出一層6奈米和10奈米的氧化鎳。 鎳-氧化鎳界面本身會形成蕭特基(Schottky)界面，此蕭特基界面大量覆蓋於鎳柱的表面，在鎳(核)-氧化鎳(殼)奈米柱上鍍上一層氧化銦錫(ITO)電極即完成ITO/NiO/Ni/Si光敏元件，我們發現不需外加電場的條件下，在紫外光照射下能產生光電反應以及較寬的吸收波長範圍，且電性以及光電反應取決於氧化鎳的厚度以及製程條件。

Nanodevice made of one-dimensional nanostructures, such as nanowires, nanobelts or nano-arrays have attracted significant research attentions, because they provide a unique platform for fundamental investigations. The interface plays a critical role in determining the electrical and optoelectronic properties of materials featuring one-dimensional nanostructures. In this work we demonstrate a facile strategy to fabricate a nano-structured device that performes notable photodetecting capabilities. Highly ordered Ni arrays were fabricated using electroless-deposition and an anodic aluminum oxide template. Upon appropriate thermal annealing (350°C). Ni-NiO nano core-shell arrays were formed, where the NiO shell displayed tunable thickness with annealing time. High resolution transmission electron microscopy (HRTEM) demonstrates that the NiO layer with thicknesses of ~ 6nm and 10nm were developed at the Ni arrays’ surfaces at 350°C for 15 minutes and 30minutes annealing, respectively. The Ni/NiO interface naturally formed a Schottky nanojunction, which largely covered arrays’ surfaces. When Ni-NiO nano-arrays were capped with an indium-tin-oxide (ITO) electrode, a ITO/NiO/Ni/Si photo-sensing device was constructed and the device was able to yield phtocurrent when exposed to ultraviolet (UV) light without an external voltage bias and exhibited a broad absorbing range. The photo-reactions and electrical properties of the ITO/NiO/Ni/Si nano-device appeared to strongly depend on NiO thickness and the fabrication details.