Secondary electron emission and self-consistent charge transport and storage in bulk insulators:: Application to alumina

The self-consistent charge transport in bulk alumina samples during electron beam irradiation is described by means of an iterative computer simulation. Ballistic electron and hole transport as well as their recombination and trapping are included. As a main result the time-dependent secondary electron emission rate sigma(t) and the spatial distributions of currents j(x,t), charges rho(x,t), the field F(x,t), and the potential slope V(x,t) are obtained. For bulk insulating samples, the time-dependent distributions approach the final stationary state with j(x,t)=const=0 and sigma=1. Especially for low electron beam energies E-0=1 keV, the incorporation of charges can be controlled by the potential V-G of a vacuum electrode in front of the target surface. Finally, for high electron beam energies, the real negative surface potential V-0<0 is measured by x-ray bremsstrahlung spectra and the shift of the short wavelength edge. For the initial beam energy E-0=30 keV, the experimental value V-0=-16 kV is still in good agreement with our simulations. (C) 2003 American Institute of Physics.