Profiling of traps in SiO2/Al2O3 gate stack by the charge pumping technique

In this paper, we present our results on the distribution and generation of traps in a SiO₂/Al₂O₃ transistor. The investigation has been carried out by using charge pumping measurements, both variable voltage and frequency techniques, and constant voltage stress.By increasing the amplitude of the gate pulse we observe an increase of the charge recombined per cycle closely related to the contribution of shallow traps near the SiO₂/Al₂O₃ interface. By reducing the pulse frequency we measure an increase in the charge pumping current due to traps located deeper in the Al₂O₃. By combining charge pumping and constant voltage stress measurements, we found that the traps are mostly generated near the Si/SiO₂ interface.