Catalyst-Free Growth of Well Vertically Aligned GaN Needlelike Nanowire Array with Low-Field Electron Emission Properties

An array of high-density, vertically aligned GaN nanowires is fabricated through thermal evaporation of GaN powder with the assistance of HCl gas. All GaN nanowires with needlelike tips are well-aligned with the axis direction perpendicular to the substrate without the use of catalysts. A possible growth mechanism of the vertical GaN nanowires array is proposed. Furthermore, field emission measurement shows that the obtained GaN nanowires array has a lower turn-on field of 2.1 V/μm, and the current density is about 1 mA/cm (2) at a bias field of 4.5 V/μm, which means such GaN nanowires are good candidates for large area and uniform flat display applications.