Charge emission in thermal poling of glasses with carbon film anode

Electric fields similar to 10(9) V/m can be induced in glass platelets at a temperature of similar to 300 degrees C and some kilovolts applied across its thickness. This glass poling process finds applications in non-linear o ptics. The electric field is confined to an alkali-ion depleted region form ed near the anode side of the sample. Partial neutralization mechanisms are assumed to take place during poling, one possibility being the emission of negative charges from the depletion region. To investigate this emission, soda lime glass platelets were poled at 270 degrees C in vacuum up to 2.5 k V. A thin (similar to 20 nm), amorphous carbon film was sputtered on one su rface of each sample and used as anode allowing eventual charges emitted to be collected in a Faraday cup. Emission occurred in pulses with similar to 200 mu s duration consisting of similar to 10(8) elementary charges of les s than or equal to 60 eV energy. The pulse occurrence probability was inver sely proportional to its charge. Charge emission was not detected with alum inum film anodes. The pulse generation process is still under inspection. ( C) 2000 Elsevier Science B.V. All rights reserved.