Influence of AlN interfacial layer on electrical properties of high-Al-content Al0.45Ga0.55N/GaN HEMT structure

Abstract

Unintentionally doped high-Al-content Al0.45Ga0.55N/GaN high electron mobility transistor (HEMT) structures with and without AlN interfacial layer were grown by metal–organic chemical vapor deposition (MOCVD) on two-inch sapphire substrates. The effects of AlN interfacial layer on the electrical properties were investigated. At 300K, high two-dimensional electron gas (2DEG) density of 1.66×1013cm−2 and high electron mobility of 1346cm2V−1s−1 were obtained for the high Al content HEMT structure with a 1nm AlN interfacial layer, consistent with the low average sheet resistance of 287Ω/sq. The comparison of HEMT wafers with and without AlN interfacial layer shows that high Al content AlGaN/AlN/GaN heterostructures are potential in improving the electrical properties of HEMT structures and the device performances.