Double- to single-hump shape change of secondary electron emission curve for thermal SiO2 layers

Secondary electron emission yields (SEEYs) were measured for silicon oxides which were thermally grown on doped silicon substrates. Generally, SEEY cu rves can be described by the so-called universal curve, i.e., one hump with a monotonic increase (decrease) before (after) the hump. However, we found that our thick oxide layers exhibited double-hump shaped SEEY curves inste ad of single-hump shaped curves. Additionally, we were able to change the s hape of a SEEY curve with two humps to a curve with one hump, or vice versa , by varying the experimental parameters. This change in curve shape can be explained if we consider the competition between the oxide layer thickness and the electron's penetration depth, the charge accumulation due to emiss ion of secondary electrons, and charge traps created during thermal oxidati on at the same time. (C) 2001 American Institute of Physics.