Acceptor and donor centers introduced by oxygen ionosorption at the a-Si:H film surface

The reversible interaction between molecular oxygen and hydrogenated amorphous silicon films is studied using conductance, photoconductance, and thermally stimulated current measurements versus temperature. The effect of the oxygen ionosorption on the electrical properties of the film has been found to be reversible. Using thermally stimulated desorption treatment, the electronic centers introduced at the film surface by the ionosorption of oxygen are highlighted. They can be described by a donor and acceptor behavior. The numerical analysis proposed corroborates the experimental interpretation. The oxygen may act equally as donor center or as acceptor center or simultaneously as acceptor and donor center localized at the a-Si:H film surface. (C) 1996 American Institute of Physics.