AlGaN/GaN HEMTs with an InGaN back‐barrier grown by ammonia‐assisted molecular beam epitaxy

Abstract We report on the study of AlGaN/GaN high electron mobility transistors (HEMTs) incorporating an InGaN back‐barrier grown by ammonia‐assisted molecular beam epitaxy (NH₃‐MBE). The structural characterizations confirm the good crystalline quality of the heterostructure and the pseudomorphic growth of InGaN. This is also verified by the Hall effect mobility of about 2130 cm² V⁻¹ s⁻¹. The associated two‐dimensional electron gas carrier concentration is in the range of 8 × 10¹² cm⁻²for heterostructures grown on GaN:Fe‐on‐sapphire templates. Normal DC transistor operation is observed. Similar results have been obtained on silicon substrates. To our knowledge, this is the first demonstration of AlGaN/GaN HEMTs with an InGaN back‐barrier grown by NH₃‐MBE.