The quasi-two-dimensional electron cyclotron mass in GaN-Al xGa1<FONT FACE=Symbol>-</FONT> xN heterostructures is theoretically calculated. The shifting in Landau Levels due to the electron Longitudinal Optical phonon interaction is calculated through the Second Order Improved Wigner Brillouin Perturbation Theory (IWBPT). Experimental results recently obtained for GaN heterojunction are well described by the theory. We have also investigated the e ects of the electronic density on the Cyclotron Resonance frequency.
