磊晶氮化鎵奈米線在藍寶石晶圓之製備及光電性質

Abstract

奈米線奈米管等一維奈米材料，因為在化學及物理上新穎且有趣的特 性而受到廣大的重視，一維半導體結構也被視為作為奈米尺寸電及光電 元件最普遍的材料。然而，處理這些奈米材料的電性接點相當不易，侷 限了其應用。我們製備了一個新型的金屬-半導體-金屬(M-S-M)的紫外光 偵測器，用磊晶氮化鎵奈米線作為光導材料。氮化鎵薄膜層用標準的微 影蝕刻技術以及反應性離子蝕刻技術來製造出溝槽寬10微米的M-S-M結 構。催化成長出連接兩端氮化鎵塊材的磊晶氮化鎵奈米線，其平均直徑 50±5 奈米，長度10±2 奈米。光導量測顯示出氮化鎵奈米線在3.4eV有 個內價帶躍遷的單一吸收。而且此紫外光偵測器量測出最大的反應度可 達到4×104 A/W，這個值遠遠大於已知的氮化鎵薄膜紫外光偵測器兩個 數量級以上。這樣高的光反應性或許來自於一維材料中較少的晶格散射 以及較高的載子遷移率。

One-dimensional (1D) nanostructures, such as NWs, NTs, have attracted much attention due to their novel and interesting properties in physics and chemistry. One-dimensional semiconducting structures have been served as the next generation materials to achieve the goal of nano-scaled electronic and optoelectronic devices. However, the difficulties in dealing with the electrical contacts on these nanosized materials have been limiting the potential applications of 1D nanostructures. In this work, we present the fabrication of a new ultra-violet (UV) detector with metal-semiconductor-metal (M-S-M) structure using epitaxially grown GaN nanowires (NWs) as the photoconducting materials. The GaN layer on the M-S-M structure was patterned in patches with 10µm gaps by standard photolithography and reactive ion etching process. The catalyst-grown GaN NWs have average diameters of 50±5 nm and lengths of 10±2 µm and link the two side walls of the GaN block electrodes. Photoconductivity (PC) spectra show that the GaN NWs exhibit a single absorption at 3.4 eV which is attributed to the inter-band transition. The maximal responsivity of the GaN NWs UV-detector is around 4×104 A/W which is higher than the reported values for GaN films by two orders of magnitude. The origin of this high responsivity of the GaN NWs could be attributed to low lattice scattering and high carrier mobility in this low-dimensional material.