An integrated electronic shutter for back-illuminated charge-coupled devices

A novel electronic shutter has been integrated into the structure of a back-illuminated frame-transfer charge-coupled device (CCD) to permit short optical exposure times and reduce the smear that occurs during the transfer of an image from the CCD detection area. The shutter consists of an n/sup +/ shutter drain placed in the channel stop regions and a stepped p-type buried layer formed by a high energy implant and located between the CCD n-type buried channel and p/sup -/ substrate. Both structures are used to create electric fields that direct the photoelectrons either toward or away from the CCD detection region. Extinction ratios (ratio of photons detected shutter open to photons detected shutter closed) greater than 5000 have been measured for wavelengths below 540 nm. The corresponding shutter rise and fall times are less than 55 ns.<>