In situ measurements of work function of indium tin oxide after UV/ozone treatment

In situ measurements of work function of indium tin oxide after UV/ozone treatment were carried out using a photoemission yield spectrometer with an open counter. Although the work function increased just after UV/ozone treatment, it decreased as time passed and finally returned to the initial value. The continuous change in work function with exposure to air was observed under dry atmosphere and at various temperatures. The returning process at higher temperature proceeded faster than at lower temperature. By contrast, humidity has no influence on the work function recovery. The exponential decay of work function was consistent with the first-order reaction rate equation. The rate constant obeyed Arrhenius' equation, and the activation energy was estimated to be 22 kJ/mol.