WORK FUNCTION VARIATIONS OF THE AG GASB (110) INTERFACE AT ROOM AND LOW-TEMPERATURE

The first stages of the interface formed between Ag and cleaved (110) surfaces of GaSb are investigated at room (RT) and low temperature (LT less-than-or-equal-to 140 K) by using the method of the vibrating capacitor. Surface photovoltage measurements are used to get informations about band bending and affinity variations. Ag depositions are made in the 10(-4)-1 angstrom range. The results are in good agreement with those obtained in the 10(-2)-1 angstrom range common to our results and ultraviolet photoemission spectroscopy (UPS) measurements. We discuss here more particularly LT results and set up different state distributions which could explain the experimental curves. Our analysis suggests that at the very beginning of the Ag deposition two successive acceptor-donor pairs are formed, followed by a more intricate system of states before reaching the monolayer. The reduction in clustering observed at LT by other methods has been a key to interpret the formation of these states. Eventually we propose a model to explain the evolution of the states involved at LT.