Electron accumulation layer at the Cs-covered GaN(0001) n-type surface

Abstract

We report on the observation of photoemission from the Cs∕GaN(0001) n-type interface by excitation of visible light in the transparency region of GaN. Under Cs adsorption, sharp decrease in photoemission threshold up to 1.3eV at 0.5 monolayer of Cs is found and shown to be due to formation of a charge accumulation layer in the near-interface region. An interesting phenomenon is revealed, namely, the appearance of an oscillation structure in spectra of photoyield. A model conception taking into account both the formation of charge accumulation layer and occurrence of multiple-beam interference in parallel-sided GaN epilayer is suggested.