Very high channel conductivity in low-defect AlN/GaN high electron mobility transistor structures

Low defect AlN/GaN high electron mobility transistor (HEMT) structures, with very high values of electron mobility (> 1800 cm(2)/V s) and sheet charge density (>3 x 10(13) cm(-2)), were grown by rf plasma-assisted molecular beam epitaxy (MBE) on sapphire and SiC, resulting in sheet resistivity values down to similar to 100 Omega/square at room temperature. Fabricated 1.2 mu m gate devices showed excellent current-voltage characteristics, including a zero gate saturation current density of similar to 1.3 A/mm and a peak transconductance of similar to 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. (C) 2008 American Institute of Physics.