Enhancing Charge Transfer Efficiency in CCDs Using SILVACO Simulations

Abstract

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