Abstract: | The longitudinal optical (LO) phonon energy in AlGaN/GaN heterostructures is determined from temperature-dependent Hall effect
measurements and also from Infrared (IR) spectroscopy and Raman spectroscopy. The Hall effect measurements on AlGaN/GaN heterostructures
grown by MOCVD have been carried out as a function of temperature in the range 1.8-275 K at a fixed magnetic field. The IR
and Raman spectroscopy measurements have been carried out at room temperature. The experimental data for the temperature dependence
of the Hall mobility were compared with the calculated electron mobility. In the calculations of electron mobility, polar
optical phonon scattering, ionized impurity scattering, background impurity scattering, interface roughness, piezoelectric
scattering, acoustic phonon scattering and dislocation scattering were taken into account at all temperatures. The result
is that at low temperatures interface roughness scattering is the dominant scattering mechanism and at high temperatures polar
optical phonon scattering is dominant. |