Nature of Electron and Hole Traps in MOS Systems with Poly-Si Electrode

A study of high-temperature annealing of MOS capacitors with poly-Si gate shows that this process creates bole traps with σ = 10−13 to 10−14 cm2 and shallow electron traps with σ = 10−15 to 10σ = 10−18 cm2 and possibly smaller. The samples also contain a deep electron trapping center with σ = 10−19 cm2, but the H2O related electron traps with σ = 10−17 to σ = 10−18 cm2 are largely absent. With the exception of the 10−15 cm2 shallow traps the other shallow and deep electron traps appear in pairs consisting of one shallow and one deep level belonging to the same center. Charge transfer between the shallow and deep levels takes place already at 100 K. These centers also act as hole traps and are most likely caused by oxygen deficiency in the oxide.