Photocurrent method for characterizing the interface of hydrophobically bonded Si wafers

We report a simple and nondestructive photocurrent method for characterizing the bonding interface between two hydrophobically bonded Si wafers. The relationship of photocurrent versus wavelength was measured and analyzed. The direction of the photocurrent indicates the band-bending direction, and thus, the donor or acceptor nature of the interface states. The photocurrent is proportional to the electric field at the interface induced by band bending. Our results showed that the Si pairs bonded in air have much larger band bending at the interface than those bonded in dry nitrogen, and that both have donor-like interface states.