Thermal reemission of trapped electrons in SiO2

Electron trapping by neutral trap centers in SiO2 was studied at 77 K and at room temperature, using n‐channel silicon‐gate IGFET structures. The electrons were injected in the dark using the forward‐bias pulsed injection method. The results show that electron trapping by the neutral centers was one to two orders of magnitude more efficient at 77 K than at room temperature; which may be compared with the previously reported electron trapping by Coulomb‐attractive centers where the capture cross sections at room temperature and at 77 K were about the same. For injected electron concentrations of less than 1016 cm−2, more than 90% of the electron trapping at 77 K was due to shallow‐level centers where the captured electrons were thermally reemitted as the samples were warmed to room temperature. The concentrations of these shallow‐level traps in dry, wet, and HCl oxides were about the same, regardless of whether the aluminum evaporation was by electron‐beam or by rf heating in a tantalum boat. The capture c...

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