PHOTON-ASSISTED FIELD ELECTRON-EMISSION FROM SIO2 SI SUBSTRATES/

We report the observation of a held-emission effect in SiO2/Si samples assisted by the presence of photons. Electric fields in the oxide of the order of 10 MV/cm(-1) are attained by photocharging during x-ray i llumination and bring the vacuum level to a position below the equilib rium Fermi level. Hot electrons are injected from the Si substrate, tr averse the SiO2 layer, and are emitted directly into vacuum. The large photocharging effect is related to the surface topography, consisting of multiple Si tips of about 1 mu m high. (C) 1996 American Institute of Physics.