Breakdown and high-energy electron vacuum emission of MIS-structures

Abstract

Vacuum emission of ballistic electrons from Au-SiO₂-Si structures has been investigated for oxide layers of various thicknesses d_ox = 13-500 nm. In particular for very thick layers and high field strength 5 MV cm^-1 we measure electron energies up to 200 eV, that is 80% of the maximum ballistic drive energy E_ball = eU_S. In order to enable such high-energy electrons to escape into vacuum very thin and deliberately non-perfect Au layers (d_Au = 8-12 nm) should be used as a top semitransparent electrode. Obviously, no energy stabilization of emitted electrons is observed. This is probably caused by defect agglomeration and the forming of defect channels. These defect channels should allow a nearly-ballistic electron transport until they are `burned-out' and `quenched-off' in a macroscopic breakdown process. What remains is damage in the form of `dead craters'.