Very High Channel Conductivity in Low-Defect AlN/GaN High Electron Mobility Transistor Structures

Abstract

Low defect AlN/GaN high electron mobility transistor (HEMT) structures, with very high values of electron mobility (\u3e1800 cm2/V s) and sheet charge density (\u3e3×1013 cm−2), were grown by rf plasma-assisted molecular beam epitaxy (MBE) on sapphire and SiC, resulting in sheet resistivity values down to ∼ 100 Ω/◻ at room temperature. Fabricated 1.2 μm gate devices showed excellent current-voltage characteristics, including a zero gate saturation current density of ∼ 1.3 A/mm and a peak transconductance of ∼ 260 mS/mm. Here, an all MBE growth of optimized AlN/GaN HEMT structures plus the results of thin-film characterizations and device measurements are presented