Optimized transport properties of GaN MISHEMTs with thin AlN interlayer

The high electron mobility and carrier density induced by the AlGaN and GaN heterojunction has exhibited great promise for high frequency and high-power applications and has attracted numerous research efforts [1]. The AlGaN/GaN high electron mobility transistors (HEMT) with a traditional Schottky metal gate suffer from large gate leakage at positive biases, and as a result, MISHEMTs with an insulating layer of high-k dielectrics is usually adopted for improved interface and leakage properties [2,3]. Moreover, previous studies show that improved output performance and reliability properties can be realized by inserting a thin AlN in between the AlGaN and GaN heterojunction [4]. In this work, detailed studies of capacitance-voltage (CV), output current, interface properties, and breakdown voltage have been carried out, and by optimizing the interface properties from both high-κ dielectrics and the AlN layer, improved transport properties can be achieved for GaN MISHEMTs.