AlGaN/GaN core–shell nanofin diodes on Si substrates for vertical GaN electronics

We demonstrate plasma-assisted MBE selective-area growth (SAG) of GaN/AlGaN core–shell structures on Si(111) as a path to vertical GaN devices. The SAG enables the full vertical and uniform core–shell fin structures to be realized in a continuous growth without breaking vacuum. TEM images and energy dispersive spectroscopy mapping of the core–shell structures show well-aligned crystal structures and sharp heterointerfaces. Dislocation filtering was observed in STEM imaging of the fin structure. p–n junction diodes fabricated with GaN/AlGaN core–shell structures reveal ideality factors as low as 1.5, and the reverse-bias leakage is consistent with trap-assisted space-charge-limited conduction. While practical challenges exist, including material-related leakage, growth-related challenges, and optimization, this demonstration of the p–n junction by this method may provide a path to vertical superjunction device concepts in GaN and related materials.