Charge fluctuations at the bonding interface in the silicon-on-insulator structures

Starting from the data of deep-level transient spectroscopy, the charge fluctuations at the interface between the top Si layer and buried insulator in Si-on-insulator structures are evaluated. The interface was prepared by bonding Si with the thermally oxidized substrate. The magnitude of fluctuations at the interface is found to be equal or exceed (1.5–2.0)×1011 cm−2 against the charge background of ∼5×1011 cm−2 at this interface. It is shown that the fluctuations are most likely associated with the negative charge at the surface states rather than with the fluctuations of the fixed positive charge within oxide.