Silicon-doped $\beta$-Ga$_2$O$_3$ films grown at 1 $\mu$m/h by suboxide molecular-beam epitaxy

Kathy Azizie; Felix V. E. Hensling; Cameron A. Gorsak; Yunjo Kim; 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; Adam T. Neal; Shin Mou; Michael O. Thompson; Hari P. Nair; Darrell G. Schlom

arXiv · 2212.12096

Silicon-doped $\beta$-Ga$_2$O$_3$ films grown at 1 $\mu$m/h by suboxide molecular-beam epitaxy

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Abstract

We report the use of suboxide molecular-beam epitaxy (S-MBE) to grow $\beta$-Ga$_2$O$_3$ at a growth rate of ~1 ${\mu}$m/h with control of the silicon doping concentration from 5x10$^{16}$ to 10$^{19}$ cm$^{-3}$. In S-MBE, pre-oxidized gallium in the form of a molecular beam that is 99.98\% Ga$_2$O, 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 $\beta$-Ga$_2$O$_3$ by conventional MBE. As a result, a growth rate of ~1 ${\mu}$m/h is readily achieved at a relatively low growth temperature (T$_{sub}$ = 525 $^\circ$C), resulting in films with high structural perfection and smooth surfaces (rms roughness of < 2 nm on ~1 ${\mu}$m thick films). Silicon-containing oxide sources (SiO and SiO$_2$) producing an SiO suboxide molecular beam are used to dope the $\beta$-Ga$_2$O$_3$ layers. Temperature-dependent Hall effect measurements on a 1 ${\mu}$m thick film with a mobile carrier concentration of 2.7x10$^{17}$ cm$^{-3}$ reveal a room-temperature mobility of 124 cm$^2$ V$^{-1}$ s$^{-1}$ that increases to 627 cm$^2$ V$^{-1}$ s$^{-1}$ at 76 K; the silicon dopants are found to exhibit an activation energy of 27 meV. We also demonstrate working MESFETs made from these silicon-doped $\beta$-Ga$_2$O$_3$ films grown by S-MBE at growth rates of ~1 ${\mu}$m/h.

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Kathy Azizie, Felix V. E. Hensling, Cameron A. Gorsak, Yunjo Kim, 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, Adam T. Neal, Shin Mou, Michael O. Thompson, Hari P. Nair, Darrell G. Schlom. 2022-12-23. Silicon-doped $\beta$-Ga$_2$O$_3$ films grown at 1 $\mu$m/h by suboxide molecular-beam epitaxy. https://arxiv.org/abs/2212.12096

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