Numerical simulation of two-dimensional electron gas characteristics of a novel (In_xAl_1-xN/AlN)MQWs/GaN high electron mobility transistor

The high electron mobility transistor (HEMT) structure employing novel In_xAl_1-xN/AlN multiple-quantum-wells (MQWs) as barrier layer is presented. The two-dimensional electron gas (2DEG) characteristics of (In_xAl_1-xN/AlN) MQWs/GaN heterojunction have been investigated by solving coupled Schrödinger and Poisson equations self-consistently. The influence of AlN thickness, In_xAl_1-xN thickness, In content and pair number of (In_xAl_{1- x}N/AlN)MQWs on sheet carrier density is investigated. AlN thickness dependence of carriers in barrier layer to total carriers in HEMT and In _0.18Al_0.82N conduction band diagrams are discussed. The sheet carrier density of (In_0.18Al_0.82N/AlN)MQWs/GaN heterojunction is larger than that of (Al_xGa_{1 -x}N/GaN)SLs/GaN heterojunction and achieves to as large as 3.59 × 10¹³ cm^-2 with AlN thickness of 1.4 nm, barrier thickness of 15 nm and pair number of 5. The calculation shows that (In_0.18Al_0.82N/AlN)MQWs provide high barrier which confines the 2DEG effectively.