Chemical Processes at Clean {1010} ZnO Surfaces Part 1.—Thermal Production of Surface Defects

Abstract

Oxygen loss from single crystal ZnO {1010} surfaces has been investigated using the method of thermally programmed desorption (t.p.d.). The t.p.d. parameters (peak area, shape, width at half height and temperature of the maximum) have been analysed in terms of O2 and Zn loss kinetics from the outermost surface atoms of the crystal only. A reaction mechanism is proposed in which both positive surface oxygen vacancies and neutral surface step sites are formed, and in which the reaction kinetics are dependent upon the fractional concentration of both kinds of surface defect (θ and θss). The maximum value of θ is 4 % and θss is ∼20 %.