Charge Transfer in CCD Cameras: Principles and Efficiency

This lecture discusses the principles of charge transfer in charge-coupled devices (CCDs) and their efficiency. It begins by explaining the concept of charge transfer between cells, emphasizing the importance of maintaining information integrity during the transfer process. The instructor describes a three-phase system for charge movement, detailing how voltages are applied to facilitate the transfer of information from one pixel to the next. The lecture introduces the fill factor, which is the ratio of the photosensitive area to the total pixel area, and its significance in CCD performance. The concept of charge transfer efficiency (CTE) is defined, highlighting its critical role in determining the effectiveness of charge movement across multiple transfers. The instructor also addresses limiting factors affecting CTE, such as diffusion currents and the impact of fringing fields on charge transport speed. The advantages of buried CCDs over surface CCDs are discussed, particularly in terms of achieving higher CTE and minimizing trapping effects. The lecture concludes with a comparison of different phase systems and their implications for charge handling capacity in CCDs.