Breakdown Voltage Enhancement of AlGaN/GaN High-Electron-Mobility Transistors via Selective-Area Growth for Ohmic Contacts over Ion Implantation

Selective-area growth (SAG) based on plasma-assisted molecular-beam epitaxy (PAMBE) was shown to facilitate improvement of Ohmic contacts and direct-current (DC) characteristics for GaN-based field-effect transistors (FETs) over the widely accepted ion-implantation technique. Twofold improvements in breakdown voltage were also demonstrated for samples grown on both sapphire and silicon substrates. An AlGaN/GaN high-electron-mobility transistor (HEMT) fabricated with PAMBE-SAG exhibited a low specific contact resistivity of 5.86 × 10⁻⁷ Ω cm², peak drain current of 420 mA/mm, and high breakdown voltage of 77 V. These results demonstrate that PAMBE-SAG is suited to fabricating HEMTs for high-power applications.