CCD Cameras: Charge Transfer and Buried Structures

This lecture discusses the principles of charge transfer and transport in charge-coupled devices (CCDs), focusing on buried CCDs (BCCDs) and their advantages over surface CCDs. The instructor begins by explaining the structure of a pixel, which consists of a central cell for collecting photo carriers and two blocking cells to prevent lateral charge movement. The importance of channel stops is emphasized to ensure that charge transport occurs vertically towards the readout register. The lecture details how high doping and thick oxide layers can reduce potential wells, thus preventing unwanted channel creation. The differences between surface CCDs and buried CCDs are highlighted, particularly regarding charge accumulation and the impact of gate voltage on performance. The instructor explains that while surface CCDs suffer from charge trapping at the surface, buried CCDs allow for charge accumulation away from the surface, improving performance. The lecture concludes with a comparison of full well capacities between buried and surface CCDs, noting the limitations of buried CCDs in terms of maximum charge accumulation.