Increase in oxide hole trap density associated with nitrogen incorporation at the SiO2/SiC interface

Nitrogen incorporation at the SiO(2)/SiC interface via high temperature nitric oxide annealing leads to the passivation of electrically active interface defects, yielding improved inversion mobility in the semiconductor. However, we find that such nitrided oxides can possess a larger density of hole traps than as-grown oxides, which is detrimental to the reliability of devices (e.g., can lead to large threshold voltage instabilities and to accelerated failure). Three different charge injection techniques are used to characterize this phenomenon in metal-oxide-semiconductor structures: x-ray irradiation, internal photoemission and Fowler-Nordheim tunneling. Some nitrogen-based atomic configurations that could act as hole traps in nitrided SiO(2) are discussed based on first-principles density functional calculations. (C) 2008 American Institute of Physics.