Oxidation states and Fermi-level pinning on GaAs(110) surface

Competition between charging and discharging surface reactions as a mechanism for the Fermi-level pinning at semiconductor surfaces

“…For n-type materials, the scheme in figure 5b provides the usual band bending that is really observed for oxygen [15][16][17][18] and sulfur [19]. In this case the charged chemisorption, B-, and the B--to-B conversion are highly plausible.…”

“…This should be typical of very electronegative adsorbates which cannot capture holes and thus are not able to create a positive surface charge. It is actually so for oxygen [15][16][17][18], sulfur [19], and chlorine [20] at low exposures characteristic of chemisorption.…”

“…Recent studies of the Fermi-level pinning at the (110) surface of GaAs have shown that a number of adsorbates give kinetics of barrier formation absolutely different in case of n-and p-type samples. For oxygen [15][16][17][18], sulfur [19], and chlorine [20] at small exposures, the barrier is formed in n-type only. p-GaAs shows practically no band bending.…”