High-aspect-ratio vertically aligned GaAs nanowires fabricated by anodic etching

Abstract

Large-scale self-aligned GaAs nanowire arrays were successfully fabricated by the anodic etching of an n-type GaAs (111)B substrate. Although pore generation occurred randomly at the early stage of anodic etching, homogeneous pore growth with a high pore density was accomplished spontaneously on the entire surface of the substrate by prolonged anodic etching under optimized conditions. The GaAs pore walls gradually dissolved during anodic etching and finally three adjacent pores were interconnected to yield a GaAs nanowire with a diameter of approximately 200 nm, a length of approximately 110 μm, and a high aspect ratio of over 500. Aggregates of GaAs nanowires exhibited a good electron emission property, a low turn-on electric field (2.5 V μm−1), and a stable field emission current. The field-emission characteristics were enhanced by increasing the spacing between emission sites through post-chemical etching.