Improving charge transfer efficiency in CCDs: A SILVACO-based numerical study

Abstract

In this study, we investigate the charge transfer efficiency (CTE) of a radiation-damaged charge-coupled device (CCD) subjected to proton radiation levels typical of space-borne experiments, nuclear imaging, and particle detection. The primary factor affecting CTE in such damaged CCDs is the trapping of charge carriers by bulk states. Our analysis examines CTE as a function of temperature, and radiation-created traps (trap levels). We employed a two-dimensional numerical model using the SILVACO semiconductor simulation software to simulate the dynamic transfer process in a buried-channel CCD (BCCD) with a three-phase clock pulse driver. After setting the appropriate physical models and the suggested deep traps levels in the channel region. The simulations demonstrate that the CTE shows a nonlinear dependence on temperature, with a charge transfer inefficiency (CTI) peaking at 7x10-6 at 135 K and reaching a minimum value of 2x10-6 around 200 K. These simulated results closely match the experimental data found in the literature, providing a comprehensive understanding of the impact of radiation-induced traps on the dynamic charge transfer processes in CCDs.