EFM Study on Ge Island: Carrier Charge and Storage Effect

In this paper, individual Ge nano island on top of a silicon dioxide layer of thermally grown on a n+ type doped silicon (001) substrate have been studied. The charging ability of an individual Ge island was evaluated by EFM two-pass lift mode measurement. Such Ge nano island becomes an iso-potential and behaves as a conductive material after being charged. These charges were directly injected and were trapped homogenous in the isolated Ge island. It is also shown that the dominant charge decay mechanism during discharging of nc-Ge is related to the leakage of these trapped charges. Further more, the retention time of these trapped charges was evaluated and the electrostatic force was also studied by using different tip bias during scan. Such a study should be very useful to the Ge-nc in memory applications.