Experimental and Theoretical Study of O2 Adsorption on the Surfaces of ZnO and CdSe Layers. Regeneration of the Surface, Calculation of Desorption Energies, Ionosorbed Species and Adsorption Kinetic Constants

Abstract

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 and CdSe layers surfaces and to determine the orders of magnitude of the interaction energies between oxygen and the superficial states of this materials, and consequently deduce ionosorbed species, thus to show the constants of the adsorption kinetics. We have used the model of T. Wolkenstein, which calculates the thermal desorption energy W_des and the model of J.C. Le Thiesse 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 1.25 to 1.50 eV, this temperatures range contains two ionosorbed species \({\text{O}}_{2}^{ - }\) and O^–. The theoretical curves adjust, shows the adsorption kinetic constants on ZnO layers at T_a = 78°C at the desorption peak (T_m = 116°C) are a = 0.2, \(a'\) = 0.9 and b = 0.2, \(b'\) = 0.01. At T_a = 110°C at the peak (T_m = 206°C) are a = 28.5, \(a'\) = 0.009 and b = 1, \(b'\) = 1.2. On CdSe layers at T_a = 121°C at the first desorption peak (T_m = 160°C) are a = 13.5, \(a'\) = 0.02 and b = 0.9, \(b'\) = 0.75, at the second peak (T_m = 222°C) are a = 7, \(a'\) = 0.008 and b = 1.2, \(b'\)= 1.5.