Dipole- and charge transfer contributions to the work function change of semiconducting thin films: Experiment and theory

In the present paper the temperature dependence of the work function change is investigated for Ga2O3-thin films (D = 1, 10, 100, 1000 nm) in a temperature region between 80 degrees C and 180 degrees C. Testing gases are 100 ppm NO2 and 100 ppm NH3 in synthetic air. Furthermore, measurements in pure nitrogen and pure synthetic air for Ga2O3-thin films are presented. The temperature coefficient of the nitrogen measurements exhibits an inverse behaviour compared to synthetic air. The experimental data are discussed in terms of the Volkenstein model, which takes into account both dipole contribution of weak and strong-chemisorbed species and charge transfer contributions.