Ultrathin Barrier InAlN/GaN Heterostructures for HEMTs

Abstract

InAlN/AlN/GaN semiconductor heterostructures with a barrier thickness of 5–13 nm have been grown by metalorganic vapor phase epitaxy (MOVPE) on sapphire and SiC substrates. Optimization of GaN buffer and InAlN layers allows fabricating structures with sheet conductivity values below 210 Ohm/sq. High electron mobility transistors (HEMTs) fabricated from such structures show drain current value exceeding 1.25 A/mm with maximum transconductance of 450 mS/mm. Use of thin in situ Si₃N₄ capping allows to fabricate and compare HEMT and MIS-HEMTs.