Elaboration and treatmant

of polycrystalline semiconductor layers

of ZnO and Sn O2  Adsorption and desorption of O2

 

N. Chahmat, A. Haddad, A. Ain-Souya, R. Ganfoudi, M. Ghers*

Laboratoire d’Etude des Surfaces et Interfaces de la Matière Solide – L.E.S.I.M.S.

Département de Physique, Faculté des Sciences, Université Badji Mokhtar , BP 12 Annaba, Algérie

* Corresponding author. E-mail: ghers_mokhtar@yahoo.fr

Received: 26 June 2008; revised version accepted: 09 August 2008

 

Abstract

     The superficial electronic properties of semiconductor materials are often sensibly affected by the interaction of strange elements with their surface states.

     The materials used for the assessment are layers of zinc ZnO and tin oxide SnO2 obtained by thermal oxidation of Zn and Sn layers at respective temperatures of 450°C and 220°C. These layers are elaborated by electrolysis on metal substrates of steel, copper and brass and by vacuum evaporation on glass plates.

The analysis by X-rays diffraction showed a preferential orientation of the grains of SnOx according to the plans (331) for the layers deposited on brass and steel substrates, (202) for the layers on copper and (002) for ZnO. The grains size is about 60nm to 30nm for layers obtained by oxidation and 200nm for those electrodeposited.

     The variations of the electric resistance of the layers measured during isothermal adsorptions and desorptions of oxygen reveal temperature ranges where the sensitivity to oxygen is high.

 

Keywords:  semiconductor; ZnO, SnO2; surface state; adsorption; oxygen.

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