Electron transport mechanism in GaN/AlGaN HEMT structures

Abstract

The electron transport mechanism in GaN/AlGaN HEMT (High Electron Mobility Transistors) structures grown with MBE on sapphire substrate was investigated by using the temperature dependence of the Hall coefficient, resistivity, carrier density and Hall mobility. Hall measurements were carried out using Van der Pauw geometry. From the LO-phonon-scattering-limited component of the mobility, we obtain LO phonon energy ~ω ≈ 90 meV and the momentum relaxation time of τm ≈ 4 fs. Also, from the temperature dependence of the 2D carrier density, we obtain the donor activation energy Ea ≈ 29 meV.