The effects of bulk traps on the performance of bulk channel charge-coupled devices

The effects of bulk traps on the transfer effciency and transfer noise in bulk channel charge-coupled devices (BCCD´s) are calculated for different charge packet sizes and operating frequencies. These predictions are compared with experimental results and the distribution and density of bulk states in actual devices are thereby measured. The measured low transfer inefficiency of 10^-4per transfer with no intentionally introduced background charge and low transfer noise are shown to be due to a low bulk state density of 2 × 10¹¹/cm³. A detailed comparison of estimated noise in both surface and bulk channel versions of an image sensor and an analog delay line show that BCCD´s are very attractive for low-light level imaging but not as attractive for analog signal processing.