Realization of improved transconductance and capacitance characteristics in Al0.3Ga0.7N/AlN/GaN HEMT

A new high performance normally-on AlGaN/GaN high electron mobility transistor (HEMT) is proposed. Its DC and microwave characteristics are observed by introducing aluminum oxide (Al2O3) as surface passivation layer. This layer reduces the trapped charge carriers for improving the two dimensional electron gas (2DEG) confinement over the Gallium Nitride (GaN) channel layer. Aluminum Nitride (AlN) layer is grown above the substrate, as nucleation layer which not only potentially improves transconductance by reducing the acceptor state trap densities but also eventually increases the on state drain current. This depletion mode AlGaN/AlN/GaN HEMT device having gate length of 1.2µm has maximum transconductance of 160ms/mm.