Oxygen ionosorption on compressed semiconducting powders of zinc and germanium oxynitrides

Oxygen ionosorption on zinc and germanium oxynitrides, Zn_xGeO_yN_z, is observed through the electrical resistance variation of pellets of these materials. In vacuum the resistance versus temperature characteristics log R₀(1/T)_are nearly straight; they show good reproducibility and are used as references for isothermal adsorption and desorption experiments and for temperature programmed desorptions (TPD). Ionosorbed oxygen acts as an electron acceptor trap at the surface of an n-type semiconductor. That leads to a resistance increase, which depends on the adsorption temperature and on the conditions of preparing the material: several ionosorption energetic levels exist in the temperature range 40 – 300 °C. This study shows that temperatures higher than 150 °C should be preferred if zinc and germanium oxynitrides are to be used and reducing gas sensor materials.