Surface Regeneration of ZnO after O2 Chemisorption - Determination of Desorption Energies and Adsorption Kinetics Constants at Ta=19°C

In this work, we present a study conducted on oxygen adsorptions and desorptions carried out on zinc oxide layers. The objective is to regenerate the ZnO layer surface and to determine the orders of magnitude of the interaction energies between oxygen and the superficial states of this material, thus to show the constants of the adsorption kinetics. We have used the model of Th. Wolkenstein, which calculates the thermal desorption energy W-des and the model of J.C. Lethiesse and R. Lalauze, which make it possible to calculate the constants of the kinetics of adsorption. The desorption signature shows peaks at temperatures T-m where some adsorbed states desorb. The values of W-des found are of the order of 0.19 to 0.51 eV. The theoretical curves adjust, shows the constants of the adsorption kinetics for three peaks of the signature. The constants of adsorption kinetics at T-a = 19 degrees C are: For the first peak (T-m = 172 degrees C) a = 10, a' = 7 and b = 4, b' = 0.7 . For the second peak (T-m = 140 degrees C) a = 29, a' = 0.9 and b = 12, b' = 0.3. For the third peak (T-m = 66 degrees C) a = 1.45, a' = 3.2 and b = 1.7, b' = 0.00009.