Effective charge density trapped upon carrier injection by three different techniques: (a) 10 keV x-rays under positive gate bias, , (b) 10 eV VUV photons under positive gate bias, , and (c) Fowler–Nordheim tunneling under negative gate bias, . The trapped charge density is calculated as , where is the oxide capacitance and is the elementary charge; negative values imply net positive charge trapping.
Evolution of the photo- hysteresis of a NO-annealed -type sample. A low intensity UV pulse was applied at , prior to the sweep toward accumulation, in order to form an inversion layer and empty deep/slow states.
Positive charge annealing in NO-treated capacitors. (a) Probability of hole emission as a function of temperature deduced from flatband recovery during isochronal annealing. (b) Fraction of the positive charge and of the generated states annealed as a function of the injected electron density.
Configurations resulting from N and NO incorporation in . The energy of the corresponding levels, are noted in electron-volts. Before trapping (labeled in black), they each have a singly occupied level and a doubly occupied level. The capture of a hole leads to a lowering of the energy states (labeled in gray). The calculated energy levels are adjusted using the experimental value for the valence band offset between 4H-SiC and amorphous .
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