Electron transport in AlGaN–GaN heterostructures grown on 6H–SiC substrates

We investigated two-dimensional electron transport in doped AlGaN–GaN heterostructures (with the electron sheet concentration $n_s{\text{≈10}}^{13}\hspace{0.17em}{\mathrm{cm}}^{\mathrm{-2}}$ ) grown on conducting 6H–SiC substrates in the temperature range $\text{T=0.3–300\hspace{0.17em}}\mathrm{K}.$ The electron mobility in AlGaN–GaN heterostructures grown on SiC was higher than in those on sapphire substrates, especially at cryogenic temperatures. The highest measured Hall mobility at room temperature was ${\mu }_H\text{=2019\hspace{0.17em}}{\mathrm{cm}}^{\mathrm{2}}\mathrm{/V\hspace{0.17em}s}.$ At low temperatures, the electron mobility increased approximately five times and saturated below 10 K at ${\mu }_H\text{=10250\hspace{0.17em}}{\mathrm{cm}}^{\mathrm{2}}\mathrm{/V\hspace{0.17em}s}.$ The experimental results are compared with the electron mobility calculations accounting for various electron scattering mechanisms.