Electron transport properties of the 2-dimensional electron gas (2DEG) in Al<sub>0.3</sub>Ga<sub>0.</sub>7 N/AlN/GaN High
Electron Mobility Transistor (HEMT) grown on Fe doped GaN template was investigated (a) experimentally
using temperature dependent Hall measurements and (b) theoretically by taking into consideration different
electron scattering mechanisms like polar optical phonon, dislocation and interface roughness scattering etc. The
HEMT structure exhibited very high electron mobilities ~1700 cm<sup>2</sup> /V s at room temperature and 13800 cm<sup>2</sup> /V s
at 30 K with a 2DEG density of ~1.1E13/cm<sup>2</sup>. From the comparison of theoretical and experimental data, it is
shown that interface roughness scattering limits the mobility at low temperature where as the high temperature
mobility is limited by Polar Optical phonon scattering.