A method for reducing
dark current within an
image sensor includes applying, at a first time period, a first set of voltages to the phases of gate electrodes of
vertical shift registers sufficient to accumulate holes of the
vertical shift register, beneath each gate
electrode and applying, at a second time period, a second
voltage to a first set of the gate electrodes while simultaneously applying a more positive
voltage to a second set of gate electrodes, the second
voltage being of sufficient potential so holes that were accumulated beneath the second set of gate electrodes during the first time are collected and stored beneath the first set of gate electrodes during the second time period. Moreover, the method applies, at a third time period, a third voltage to the second set of gate electrodes while simultaneously applying a more positive voltage to the first set of gate electrodes, such that the previously accumulated holes beneath the first set of gate electrodes are transferred beneath the second set of gate electrodes; and returns the first and second sets of gate
electrode voltages to their levels at the first time period.