Acoustic phonon scattering on the two-dimensional electron gas in wurtzite AlxGa1−xN/GaN/AlyGa1−yN double heterostructures: The ternary mixed crystal effect and size effect

Based on the elastic continuum model and Fermi golden rule, the ternary mixed crystal effect and size effect on the mobility of two-dimensional electron gas influenced by the scattering from acoustic phonons via deformation potential in a wurtzite AlxGa1−xN/GaN/AlyGa1−yN double heterostructure at 77 K are discussed theoretically. The results show that the increase of the Al component in AlxGa1−xN barrier changes the symmetry and vibration modes of acoustic phonons, leading an abrupt increase of the total mobility in a certain Al component region for an asymmetrical heterostructure. Besides, the total mobility reaches a maximum around a certain thickness of channel layer GaN. These effects give a guidance to improve the properties of high electron mobility transistors.

► The scattering from the dilatational acoustic mode is dominant.
► The ternary mixed crystal effect changes vibration modes of acoustic phonons.
► An abrupt increase of the total mobility in a certain Al component region.
► The total mobility reaches a maximum around a certain thickness of channel layer GaN.
► The ternary mixed crystal effect and size effect give a guidance to improve HEMTs.