Photoionization cross section of electron traps in thin oxynitride films of metal‐oxynitride‐oxide‐silicon devices

摘要

The flat‐band voltage monitored photodepopulation technique in combination with photoinjection was used to investigate the first‐order kinetics of a trap emptying in low‐pressure chemical vapor deposited thin films of silicon oxynitride (SiOxNy) of metal‐oxynitride‐oxide‐silicon devices. An effective photoionization cross section associated with deep electron traps was determined to be 4.9–18.9×10−19cm2over the photon energy range of 2.06–3.1 eV for oxynitride films containing 7–17 at.  of oxygen. At a fixed oxygen concentration, the photoionization cross section decreased from 8.3×10−19to 4.9×10−19cm2as the photon energy was lowered from 2.06 to 2.48 eV. However, the photoionization cross section at a fixed photon energy within this range showed an average decrease of 18 for a 10 increase in the amount of oxygen content in the oxynitride film. The photoionization cross section increased from 4.9×10−19to 18.9×10−19cm2as the photon energy was increased from 2.48 to 3.1 eV. Over this higher photon energy range, a 28 decrease in photoionization cross section was observed for the same 10 increase of oxygen content in the oxynitride films.