Charge trapping and retention behaviors of Ge nanocrystals distributed in the gate oxide near the gate synthesized by low-energy ion implantation

Abstract

A layer of Ge nanocrystals (nc-Ge) distributed in the gate oxide near the gate of a metal-oxide-semiconductor structure is synthesized with low-energy Ge ion implantation followed by thermal annealing at 800 °C. The behaviors of charge trapping and charge retention in the nc-Ge have been studied. For a positive charging voltage, only electron trapping occurs, and the trapped electrons show a long retention time. However, for a negative charging voltage, both the hole trapping and electron trapping occur simultaneously, and the hole trapping is dominant if the magnitude of the charging voltage is small or the charging time is short. Due to the relatively easier loss of the trapped holes, the net charge trapping in the nc-Ge exhibits a continuous shift toward a more negative value with the waiting time. © 2007 American Institute of Physics.