Surface plasmons at MOCVD-grown GaN

We report on the first observation of surface plasmons at a GaN surface by high-resolution electron energy loss (HREEL) spectroscopy. Dipole scattering theory using self-consistent electron density profiles is employed to calculate the surface energy loss function and hence the expected energy loss spectra. The characteristic features of both the surface plasmons and the Fuchs-Kliewer (FK) surface optical phonons are well reproduced in the framework of this model. Fitting measured HREEL spectra allows us to give estimates of important semiconductor parameters such as electron density, electron mobility and band bending. Moreover, it is found that the plasmon damping strongly depends on primary beam energy. Similarly, the FK phonon damping and frequency are also affected by the variation of primary beam energy.