1. Silicon-doped β-Ga2O3 films grown at 1 µm/h by suboxide molecular-beam epitaxy
- Author
-
Kathy Azizie, Felix V. E. Hensling, Cameron A. Gorsak, Yunjo Kim, Naomi A. Pieczulewski, Daniel M. Dryden, M. K. Indika Senevirathna, Selena Coye, Shun-Li Shang, Jacob Steele, Patrick Vogt, Nicholas A. Parker, Yorick A. Birkhölzer, Jonathan P. McCandless, Debdeep Jena, Huili G. Xing, Zi-Kui Liu, Michael D. Williams, Andrew J. Green, Kelson Chabak, David A. Muller, Adam T. Neal, Shin Mou, Michael O. Thompson, Hari P. Nair, and Darrell G. Schlom
- Subjects
General Engineering ,General Materials Science - Abstract
We report the use of suboxide molecular-beam epitaxy ( S-MBE) to grow β-Ga2O3 at a growth rate of ∼1 µm/h with control of the silicon doping concentration from 5 × 1016 to 1019 cm−3. In S-MBE, pre-oxidized gallium in the form of a molecular beam that is 99.98% Ga2O, i.e., gallium suboxide, is supplied. Directly supplying Ga2O to the growth surface bypasses the rate-limiting first step of the two-step reaction mechanism involved in the growth of β-Ga2O3 by conventional MBE. As a result, a growth rate of ∼1 µm/h is readily achieved at a relatively low growth temperature ( Tsub ≈ 525 °C), resulting in films with high structural perfection and smooth surfaces (rms roughness of 2) producing an SiO suboxide molecular beam are used to dope the β-Ga2O3 layers. Temperature-dependent Hall effect measurements on a 1 µm thick film with a mobile carrier concentration of 2.7 × 1017 cm−3 reveal a room-temperature mobility of 124 cm2 V−1 s−1 that increases to 627 cm2 V−1 s−1 at 76 K; the silicon dopants are found to exhibit an activation energy of 27 meV. We also demonstrate working metal–semiconductor field-effect transistors made from these silicon-doped β-Ga2O3 films grown by S-MBE at growth rates of ∼1 µm/h.
- Published
- 2023