【International Papers】High-quality MOCVD-grown heteroepitaxial gallium oxide growth on III-nitrides enabled by AlOx interlayer

      Researchers from the Center for Quantum Devices, Department of Electrical and Computer Engineering, Northwestern University have published a dissertation titled " High-quality MOCVD-grown heteroepitaxial gallium oxide growth on III-nitrides enabled by AlO_x interlayer " in Applied Physics Letters.

Abstract

      We report high-quality Ga₂O₃ grown on an AlGaN/AlN/Sapphire in a single growth run in the same Metal Organic Chemical Vapor Deposition reactor with an AlO_x interlayer at the Ga₂O₃/AlGaN interface. AlO_x interlayer was found to enable the growth of single crystalline Ga₂O₃ on AlGaN in spite of the high lattice mismatch between the two material systems. The resulting nitride/oxide heterogenous heterostructures showed superior material qualities, which were characterized by structural, electrical, and optical characterization techniques. In particular, a significant enhancement of the electron mobility of the nitride/oxide heterogenous heterostructure is reported when compared to the individual electron mobilities of the Ga₂O₃ epilayer on the sapphire substrate and the AlGaN/AlN heterostructure on the sapphire substrate. This enhanced mobility marks a significant step in realizing the next generation of power electronic devices and transistors.

Figure 1（a）SEM cross section images of heteroepitaxial III-Nitride/Oxide epilayers. (b) Top-view SEM images showing the surface morphologies of the films without and with AlO_x (c) RMS value of Ga₂O₃epilayers as a function of AlO_x interlayer deposition time.

Figure 2 XRD 2θ–ω scan of (a) AlGaN/AlN on Sapphire, (b) κ-Ga₂O₃ on Sapphire, (c) β-Ga₂O₃ on Sapphire, (d) κ-phase NOH sample with AlO_x deposition time of 5 s, and (e) β-phase NOH sample with AlO_x deposition time of 5 s.

Paper Link：https://doi.org/10.1063/5.0170383