Bottom-up vertical GaN nanocolumn Schottky barrier diodes with extremely high packing density grown by molecular beam epitaxy

Abstract

In this paper, we report achieving extremely high-density packing in high-voltage vertical gallium nitride (GaN) nanocolumn Schottky barrier diodes (NC-SBDs) through the adoption of a bottom-up process. The NC-SBDs were formed via epitaxial growth using Titanium-mask selective area growth (Ti-SAG) by rf-plasma-assisted molecular beam epitaxy (rf-MBE), realizing a packing density equivalent to exceeding 10 million columns/mm². Our fabricated NC-SBDs with a period of 300 nm, a diameter of 250 nm, and a drift length of 1.3 μm demonstrated a breakdown voltage of 260 V with an on-resistance of 2.0 mΩcm², yielding an excellent figure of merit (FoM) of 38.8 MW/cm² for nanocolumn-based high-voltage devices. We also discuss dielectric reduced surface field (RESURF) effect and impurities within the nanocolumns as potential factors contributing to the achievement of higher breakdown voltage devices.