Electron-multiplication image sensor

An image sensor having active-pixels formed in a semiconductor substrate, each active-pixel comprising, at the surface of a semiconductor active layer, a photodiode region, a charge storage node, a read transistor for reading the charges stored in the storage node, a reset transistor for resetting the potential of the storage node, and a transfer structure for transferring charges from the photodiode region to the storage node after a charge integration time for charges generated by light in the photodiode region, wherein the transfer structure comprises:

• a first transfer gate adjacent to the photodiode region,
• a second transfer gate adjacent to the storage node,
• an amplifying structure located between the first and second transfer gates and comprising two separate accelerating gates,
• an intermediate diode region at a fixed surface potential, located between the two accelerating gates,
• means for firstly applying to the first transfer gate a first transfer pulse for charge transfer from the first transfer gate to at least one first accelerating gate,
• means for then applying to the accelerating gates a succession of alternating high and low potentials for successive charge transfer from one accelerating gate to the other through the intermediate diode region,
• and means for then applying to the second transfer gate a second transfer pulse for charge transfer from the accelerating gates to the storage node.