학술논문
Silicon-doped $\beta$-Ga$_2$O$_3$ films grown at 1 $\mu$m/h by suboxide molecular-beam epitaxy
Document Type
Working Paper
Author
Azizie, Kathy; Hensling, Felix V. E.; Gorsak, Cameron A.; Kim, Yunjo; Dryden, Daniel M.; Senevirathna, M. K. Indika; Coye, Selena; Shang, Shun-Li; Steele, Jacob; Vogt, Patrick; Parker, Nicholas A.; Birkhölzer, Yorick A.; McCandless, Jonathan P.; Jena, Debdeep; Xing, Huili G.; Liu, Zi-Kui; Williams, Michael D.; Green, Andrew J.; Chabak, Kelson; Neal, Adam T.; Mou, Shin; Thompson, Michael O.; Nair, Hari P.; Schlom, Darrell G.
Source
Subject
Language
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.
Comment: 19 pages, 7 figures, 2 tables, 2 pages supplementary materials
Comment: 19 pages, 7 figures, 2 tables, 2 pages supplementary materials