Determination of charge handling capability of a deep depletion charge coupled device based on a three-dimensional numerical simulation

Abstract

A JET-X (Joint European X-ray Telescope) CCD fabricated on a high-purity (1.5 k(Omega) cm), 65 micrometers thick epi-layer, on a 550 micrometers thick p<SUP>+</SUP> substrate has been developed for X-ray astronomy. A 3D numerical analysis for evaluating a charge handling capability and charge transfer efficiency of a JET-X CCD using a static and transient simulation has been performed. A supplementary channel technique is analyzed by the 3D simulation. A static maximum charge capacity was found to be 60040 electrons under a full- well condition. The effect of an output gate voltage on charge transfer between the last well and an output diffusion node was observed and an optimum output gate voltage for efficiency charge transfer was found to be 3 or 4 V. A time-dependent simulation was performed to observe the dark current contribution, to very the static, full-well capacity and to estimate the charge transfer efficiency (CTE). The dark current source has found to be &lt; 1 electron per pixel for a clock cycle, T equals 1.85 microsecond(s) . The CTE was &gt; 99.999% for a pixel clock cycle of 4.2 ns with a fall time of 0.4 ns. The dynamic, full-well capacity was higher than the static, full-well capacity by appr. 1.8%. The 3D simulated result showed a higher charge capability by appr. 18% than result from a 1D model.