Glass-ITO system as electron emitter

The thin transparent and conductive Sn doped In2O3 layers have been deposited onto both surfaces of the glass plate of dimensions 0.2x16x16 mm using the constant-current ion sputtering method. In order to study the electron emission the voltage has been applied between both the ITO layers. One of the layers was 1 micrometers thick (the field electrode) and another one (10nm and much thinner) was deposited onto the opposite surface of the glass. This thin layer was treated as the electron emitter. The polarizing voltage Upol has been applied to the field electrode. The study has been carried out in vacuum (10MIN7hPa). The multichannel analyzer of amplitude of voltage pulses created by the electron multiplier has been used in order to record the electron emission yield. Aside of the field effects the studies concerning the result of UV illumination on the photo emission monitored by field has been examined. Determined were the amplitude spectrum of the voltage pulses for various polarizing voltage. The same method was used to find the dependence of the pulse frequency n on the applied voltage Upol. The exponential dependence n = f(Upol) has been found. The field induced emission mechanism can be explained on the basis of the well known phenomena occurring in semiconductors under influence of strong electric field (the hot electron effect, the impact ionization, the Gunn effect, the tunnel effect, etc.). It was also found that additional effect at simultaneous emission of two electrons as a result of absorption of a single photon have to be taken into account. The existence of this effect has been proved by decomposition of the amplitude spectrum into Gaussians. Measurements of electron energy in the field induced emission showed that about 80% of electrons have energy up to 10 eV. Photo induced optical second harmonic (SHG) has been also observed in these films.