High-electron-mobility AlGaN∕AlN∕GaN heterostructures grown on 100-mm-diam epitaxial AlN/sapphire templates by metalorganic vapor phase epitaxy

${\mathrm{Al}}_{0.26}{\mathrm{Ga}}_{0.74}\mathrm{N}∕\mathrm{Al}\mathrm{N}∕\mathrm{Ga}\mathrm{N}$ heterostructures with $1\text{-}\mathrm{nm}$ -thick AlN interfacial layers were grown on $100\text{-}\mathrm{mm}$ -diam epitaxial AlN/sapphire templates and sapphire substrates by metalorganic vapor phase epitaxy. It was found that AlN/sapphire templates significantly enhanced the electron mobility of the two-dimensional electron gas (2DEG) confined at the GaN channel. This can be explained by the high-crystal-quality GaN channel realized by the use of epitaxial AlN/sapphire templates as substrates. The very high Hall mobilities of approximately $2100{\mathrm{cm}}^2∕\mathrm{V}\mathrm{s}$ at room temperature and approximately $17000{\mathrm{cm}}^2∕\mathrm{V}\mathrm{s}$ at $77\mathrm{K}$ with a 2DEG density of approximately $1\times {10}^{13}∕{\mathrm{cm}}^2$ were uniformly obtained for $\mathrm{Al}\mathrm{Ga}\mathrm{N}∕\mathrm{Al}\mathrm{N}∕\mathrm{Ga}\mathrm{N}$ heterostructures on $100\text{-}\mathrm{mm}$ -diam epitaxial AlN/sapphire templates. The Hall mobility of $\mathrm{Al}\mathrm{Ga}\mathrm{N}∕\mathrm{Al}\mathrm{N}∕\mathrm{Ga}\mathrm{N}$ heterostructures on epitaxial AlN/sapphire templates reached a very high value of $25500{\mathrm{cm}}^2∕\mathrm{V}\mathrm{s}$ at $15\mathrm{K}$ .