Shin Jeong Ho, Rhu Hyun, Ji Young Bin, Oh Seung Jae, Lee Woo
Korea Research Institute of Standards and Science (KRISS), Yuseong, Daejeon 34113, Republic of Korea.
Gimhae Industry promotion & Bio-medical Foundation (GIBF), Gimhae, 50969 Gyeongnam, Republic of Korea.
ACS Appl Mater Interfaces. 2020 Nov 11;12(45):50703-50712. doi: 10.1021/acsami.0c13574. Epub 2020 Oct 30.
A generic top-down approach for the preparation of extended arrays of high-aspect ratio GaAs nanowires (NWs) with different crystallographic orientations (i.e., [100] or [111]) and morphologies (i.e., porous, nonporous, tapered, or awl-like NWs) is reported. The method is based on the anodically induced chemical etching (AICE) of GaAs wafers in an oxidant-free aqueous HF solution at room temperature by using a patterned metal mesh and allows us to overcome the drawbacks of conventional metal-assisted chemical etching (MACE) processes. Local oxidative dissolution of GaAs in contact with a metal is achieved by externally injecting holes () into the valence band (VB) of GaAs through the metal mesh. It is found that injection of holes () through direct GaAs contact, rather than the metal mesh, does not yield uniform nanowires but porosify GaAs wafers due to the high cell potential. On the basis of experiments and numerical simulation for the spatial distribution of an electric field, a phenomenological model that explains the formation of GaAs NWs and their porosification behaviors is proposed. GaAs NWs exhibit excellent terahertz (THz) wave emission properties, which vary with either the length or the shape of the nanowires. By taking advantage of controlled porosification and easy transfer of GaAs NWs to foreign substrates, a flexible THz wave emitter is realized.
报道了一种通用的自上而下的方法，用于制备具有不同晶体取向（即[100]或[111]）和形貌（即多孔、无孔、锥形或锥状纳米线）的高纵横比砷化镓纳米线（NWs）扩展阵列。该方法基于在室温下，通过使用图案化金属网在无氧化剂的水性氢氟酸溶液中对砷化镓晶片进行阳极诱导化学蚀刻（AICE），使我们能够克服传统金属辅助化学蚀刻（MACE）工艺的缺点。通过金属网将空穴（）外部注入到砷化镓的价带（VB）中，实现与金属接触的砷化镓的局部氧化溶解。研究发现，通过直接砷化镓接触而非金属网注入空穴（），不会产生均匀的纳米线，而是由于高电池电位使砷化镓晶片多孔化。基于电场空间分布的实验和数值模拟，提出了一个解释砷化镓纳米线形成及其多孔化行为的唯象模型。砷化镓纳米线表现出优异的太赫兹（THz）波发射特性，其随纳米线的长度或形状而变化。通过利用可控的多孔化以及将砷化镓纳米线轻松转移到异质衬底上，实现了一种柔性太赫兹波发射器。
