By incorporating on-chip multiplication gain, the electron multiplying CCD achieves, in an all solid-state sensor, the single-photon detection sensitivity typical of intensified or electron-bombarded CCDs at much lower cost and without compromising the quantum efficiency and resolution characteristics of the conventional CCD structure.
Innovations in silicon based CCD technology have created many varieties of CCDs. With the quantum efficiency of the traditional front-illuminated CCD reaching about 70 percent and the more advanced back-thinned design achieving more than 90 percent, detection limits are nearing their theoretical values. Signal detection in modern CCDs is often limited by how much camera noise (due to dark current and readout) must be overcome before the signal is apparent on the CCD. These values determine the camera performance of CCD, especially in low light applications.