A highly sensitive on-chip charge detector for CCD area image sensor

A novel on-chip charge detector for charge-coupled-device (CCD) image sensor applications was fabricated and evaluated. The device, called the double-gate floating surface detector, achieves a charge/voltage conversion gain of 220 μV/electron, a noise equivalent electron of 0.5 electrons r.m.s. and a dynamic range of 79 dB over 3.58-MHz video bandwidth at room temperature. In the small-signal region under 20 electrons, which is the photon counting region for highly sensitive imaging devices, the device was evaluated by observing the discrete voltage levels corresponding to the number of signal electrons on an oscilloscope. This evaluation confirmed that the high charge voltage conversion gain is also maintained in this region