Vacuum emission of hot electrons from GaAs

Intrinsic GaAs layers up to 3 /spl mu/m on highly doped n/sup ++/-substrate were covered with very thin Au-layers (10 nm) in order to manufacture planar field emission cathodes. At a tenfold Gunn-field of about 50 kV/cm we observe the beginning of hot and ballistic electron emission into vacuum. The energy analysis of them shows energy distributions over several eV exceeding for thick samples even 10 eV. We give a description of that high energy transport by means of Monte-Carlo calculations including acoustic and optical phonon interaction of electrons, intervalley scattering and impact ionization of valence band electrons. In a similar way, by means of vacuum emission experiments, EBIC and MC calculations we have evidenced high field transport in ZnS and SiO/sub 2/, too.