Tracking Electron and Hole Trap Densities on Commercial Display Glass

Surface charges can cause problems in industry dealing with high voltage applications. In current literature, charge measurements on glass surfaces are lacking. Furthermore, no operando measurements on these charges can be performed, due to the invasiveness of the available diagnostics. In this research, an operando measurement technique, based on the Pockels effect is introduced that can be applied to glass (among other dielectrics). Furthermore, an electrostatic voltmeter is used for surface potential measurements on commercial display glass in open air. Surface charge deposition is done using an X-ray ionizer. Subsequently, the decay of the surface potential, induced by the surface charges, is translated to trap density using the isothermal surface potential decay model. The energy distribution is shown to be comparable for electron and hole traps with a peak at approximately ~0.88 eV and 0.89 eV respectively. However, the surface charge spreading is observed to be faster for negative charges. The energy and density of traps cannot be assessed yet with Pockels, because of low sensitivity, while the time and spatial resolution of the proposed method are potentially better than existing techniques.