Photoemission study of the effect of annealing temperature on a K2O2/Si(100) surface

Photoelectron spectroscopy and work-function measurements have been used to study a K2O2/Si(100) surface as a function of annealing temperature. The r esults show that the features for K2O2 gradually move to high binding energ y, and the work function decreases with increasing temperature up to 460 K. As the species of K2O2 decomposes at 540 K, there exist two kinds of oxyge n bonding states. A thin K-O layer is formed on the top surface, while oxyg en bonded to silicon is located at subsurface, leading to an extremely low value (0.3 eV) of the work function. For further annealing, the oxygen bond ed to potassium gradually transfers to Si due to the desorption of potassiu m, and Si-O bonds appear on the top layer, which is related to increases of the work function. [S0163-1829(99)13647-6].