Highly reliable long-term operation of AlGaN/GaN/AlN HFETs grown on silver substrate

We developed a novel "combined" two-step epitaxial procedure based on MO VP E and MB E for an optimized growth of group III-nitride layers on silver-metallic substrates. The AlGaN/GaN/AlN heterostructures were used for the fabrication of HFETs. The electrical properties as well as the long-term operation properties were systematically studied and compared with conventional devices. The improved heat dissipation in heterostructures deposited directly on a silver substrate leads to a significant decrease in channel temperature (−60% at 7W/mm) and affects the long term stability of the drain current (± 2%) favorably in the whole range under investigation (up to ∼1000 hours) compared with conventional AlGaN/GaN layers grown on sapphire substrates. The results presented demonstrate the great potential of the novel material-device concept.