First principle calculations of phonon-limited electron mobility in GaN

For many advanced applications of GaN, electron mobility plays a key role in the device performance. Phonon strongly impacts electron scattering and thus electron mobility for a wide range of temperatures and carrier concentrations. However, the mechanism of electron-phonon scattering remains to be explored in GaN. Using density functional theory, we computed carrier scattering rate and transport properties for zinc blende n-type GaN with carrier concentration (n) of 10¹⁵ to 10¹⁹ cm^-3 in the temperature range of 100 to 400 K. The calculated Hall mobility shows good agreement with experimental data. Furthermore, we found that the mobility remains the same for lightly doped (10¹⁵ < n < 10¹⁷ cm^-3) cases, which is explained by values of the occupation numbers in scattering rate expression. We also found that electrons with mean free paths (MFPs) below 40 nm at n = 10¹⁷ cm^-3 (30 nm at n = 10¹⁹ cm^-3) provide dominant contribution to electron transport at 300 K, shedding light on GaN-related nanoengineering.