Characterization of β-Ga <sub>2</sub> O <sub>3</sub> homoepitaxial films and MOSFETs grown by MOCVD at high growth rates
Marko J. Tadjer, Fikadu Alema, A. Osinsky, Michael A. Mastro, Neeraj Nepal, J. Woodward, Rachael L. Myers‐Ward, E. R. Glaser, Jaime A. Freitas, Alan G. Jacobs, James C. Gallagher, A. Mock, Daniel J. Pennachio, Jenifer R. Hajzus, Mona A. Ebrish, Travis J. Anderson, Karl D. Hobart, Jennifer K. Hite, Charles R. Eddy
Abstract
Abstract The ultra-wide bandgap semiconductor gallium oxide (Ga 2 O 3 ) offers substantial promise to significantly advance power electronic devices as a result of its high breakdown electric field and maturing substrate technology. A key remaining challenge is the ability to grow electronic-grade epitaxial layers at rates consistent with 20–40 μ m thick drift regions needed for 20 kV and above technologies. This work reports on extensive characterization of epitaxial layers grown in a novel metalorganic chemical vapor deposition tool that permits growth rates of 1.0–4.0 μ m h −1 . Specifically, optical, structural and electrical properties of epilayers grown at ∼1 μ m h −1 are reported, including employment in an operating MOSFET. The films demonstrate relatively smooth surfaces with a high degree of structural order, limited point defectivity (N d − N a ≈ 5 × 10 15 cm −3 ) and an optical bandgap of 4.50 eV. Further, when employed in a MOSFET test structure with an n + doped channel, a record high mobility for a transistor structure with a doped channel of 170 cm 2 V −1 s −1 was measured via the Hall technique at room temperature. This work reports for the first time a β-Ga 2 O 3 MOSFET grown using Agnitron Technology’s high growth rate MOCVD homoepitaxial process. These results clearly establish a significant improvement in epilayer quality at growth rates that can support future high voltage power device technologies.