Photoemission-induced charging of self-assembled Au nanoparticles on GaN substrates and the effect on surface band bending

The effects of Au nanoparticles on the electronic properties of a GaN surface were investigated using synchrotron radiation photoelectron spectroscopy (SRPES). A 30-Å-thick Au film on GaN was transformed to nanoparticles by annealing at 300 °C. Ga 3d core level peak as well as Au 4f for p-GaN shifted towards higher binding energies with the formation of Au nanoparticles, while peak shifts in the SRPES spectra for n-GaN were negligible. Poor conductivity of the p-GaN substrate and high resistance between Au nanoparticles and the p-GaN led to positive charges being distributed on the p-GaN surface, suggesting that Au nanoparticles on p-GaN strongly affect the evaluation of surface band bending and the measurement of Schottky barrier heights by photoemission spectroscopy.