Back-illuminated CCDs are sensitive to kilovolt-energy electrons incident on the back surface through the EBS gain process. The incident electron loses energy through a series of inelastic collisions that result in the production of electron-hole pairs at the rate of about one per 3.64 eV. Due to the correlated nature of the electron cascade, the variance in the number of pairs created is reduced below shot noise by the Fano factor (approximately 0.12 in silicon). This lowering of noise in the gain process leads to system noise being limited by the shot noise of the incident photoelectron signal.

The incident electron is absorbed very close to the silicon surface and for energies up to 10 keV creates all of it's 'child' electron-hole pairs within the first micron. If nothing were done to accumulate the back surface, the electric field caused by the presence of charged native oxide would tend to force the electrons to the back surface where they could recombine. Backside enhancement techniques such as UV charging, ion implanting, and annealing and flash gate technologies are designed to reverse the field near the surface so that electrons generated there are repelled and collected in the CCD well. Between the field at the back surface and the buried potential well there is a field-free region of some thickness; the thickness is a process parameter. In high quality silicon, the diffusion constant is much longer than the field free region, thus the 'child' electrons drift fairly unimpeded through this region. The spatial distribution in the CCD well depends on the angle of emission of the electron in the pair creation process as well as the distance from the point of emission to the edge of the depletion region. The result is charge spreading and degradation of spatial resolution.

Although kilovolt-energy electrons primarily produce electrons in silicon, X-rays are also generated, mainly the 1.74 keV K_a characteristic with 11.9 µm 1/e attenuation depth, but also broad-band Bremsstrahlung. A percentage of these X-rays travel through the silicon to be absorbed in the gate dielectric where they can cause a flat-band voltage shift or in the silicon-dielectric interface where they can create additional interface states -- a source of dark current in non-MPP operation. A practical way to reduce X-ray radiation damage is to reduce the electron energy below 1.74 keV. Thicker expitaxial silicon also reduces damage, but does so at the expense of spatial resolution.

The proximity-focused EBCCD image intensifier is much less complicated in design than the ICCD. The ultra-high vacuum requirement of the GaAs photocathode dictates that no organics be used in the CCD fabrication process and packaging, and the CCD must withstand tube bake-out temperatures. The assembly tolerances are looser than those of a tube incorporating an MCP. In addition, the size and weight of the EBCCD tube is much less than the standard image intensifier.