Abstrait

Adsorpion and Desorption Of Oxygen on Surfaces Oxide Semiconductor Binary

A Haddad, A Hafidi, N Chahmat, A Ain-Souya, R Ganfoudi, and M Ghers

The regeneration of binary semiconductor layers after isothermal adsorptions of oxygen at various temperatures carried out between 20°C and 350 °C has been studied. The used samples are layers of CdSe obtained by vacuum evaporation on glass substrates, ZnO and SnO2 oxide layers. These last were grown by oxidation of Zn and Sn layers at respective temperatures of 450°C and 200°C under O2 gas. The considered layers of metals were prepared by the techniques of vacuum evaporation on glass, alumina and metal substrates, and electrodeposition on metal substrates of various natures (copper, aluminium, steel…). The experimental results show that during adsorption of oxygen, the electric resistance measured between two points of the samples surface varies as a function of the temperature and the nature of the samples. The layers of CdSe and ZnO strongly adsorb oxygen at high temperatures around 200°C, while the rate of maximum adsorption of O2 by SnO2 is obtained at lower temperatures. The isothermal desorption carried out at the same temperatures of adsorption show that the layers can be regenerated but for relatively long lengths of time. The layers reheated under O2, at temperatures chosen, are less sensitive to this element. Total regeneration proves the reversible nature of the oxygen interaction with surface and informs about the stability of the material