Hybrid photosensor

The invention relates to hybrid photosensors produced on two distinct substrates S1 and S2, one carrying photosensitive elements (for example photovoltaic diodes 10) and the other carrying read circuits for transforming a photosensitive current into charge packets. The read circuit includes an input diode (region 12), an injection gate (14) overhanging a channel and a storage gate (16) establishing a deep potential well in the region 18 which it overhangs. The problem of the stability of the bias of the channel potential with respect to the second substrate and with respect to the input diode is resolved in the following way: first of all the channel (22) is doped with the type opposite to the substrate; next, the injection gate is highly biased negatively (-5 to -10 volts); finally, the first substrate is biased to a positive voltage with respect to the second substrate. The channel potential then becomes insensitive to the charge variations in the gate insulation.