Photoemitters based on the field and optical induced electron emission

摘要

Electron emission properties of doped In_2O_3 and SnO_3 (ITO) thin layers have been studied. These layers have been deposited onto both surfaces of a microscope glass using a constant-current ion sputtering method. One of the layer (1 μm thick) was a field electrode and another one (10nm - 200nm) was treated as an electron emitter. The layers were examined using an electron emission induced by electric field. The polarizing voltage U_(pol) has been applied to the field electrode. The studies has been carried out in vacuum (10~(-7) hPa). Electron emission yield dependence on the intensity of an internal field and illumination were measured. The exponential dependence of the pulse frequency n = f(U_(pol)) has been found. With increasing U_(pol) (field strength in a sample) and after illumination the count frequency of pulses grows monotonically. At low U_(pol) (≤| -500V |) the increase is linear. At higher U_(pol) this dependence is exponential. Energy analysis of emitted electrons was performed by the retarding field method. Measurements of electrons energy in field induced emission showed that about 80% of electrons have energy up to 10 eV. It was also found that additional effect at simultaneous emission of two electrons as result of absorption of a single photon have to be taken into account.