[Paper Review] Modeling charge coupled device readout: Simulation overview and early results

Paul Bristow, A. Alexov|arXiv (Cornell University)|Nov 29, 2002

CCD and CMOS Imaging Sensors2 references3 citations

TL;DR

This paper presents a physical model of charge transfer in modern Charge-Coupled Devices (CCDs), specifically applied to the Hubble Space Telescope's Space Telescope Imaging Spectrograph (STIS). By incorporating radiation-induced defects in the silicon lattice and using Philbrick's trapping and emission model, the simulation closely matches real STIS calibration data, demonstrating the feasibility of physics-based calibration improvements despite remaining uncertainties in model details.

ABSTRACT

The Calibration enhancement effort for the Space Telescope Imaging Spectrograph (STIS) aims to improve data calibration via the application of physical modelling techniques. We describe here a model of the Charge Transfer process during read-out of modern Charge Coupled Devices, and its application to data from STIS. The model draws upon previous investigations of this process and, in particular, the trapping and emission model developed by Robert Philbrick of Ball Aerospace. Early comparison to calibration data is encouraging. Essentially, a physical description of the STIS CCD combined with the physics of known defects in the silicon lattice expected to arise in a hostile radiation environment, is enough to yield results which approximately match real data. Uncertainties remain, however, in the details of the model and the physical description of STIS.

Motivation & Objective

• Improve data calibration for the Space Telescope Imaging Spectrograph (STIS) using physical modeling.
• Address limitations in current calibration methods by modeling charge transfer inefficiencies during CCD readout.
• Investigate the impact of radiation-induced defects in the silicon lattice on charge transfer in space-based CCDs.
• Validate the model against real STIS calibration data to assess accuracy and reliability.
• Enhance the fidelity of on-orbit CCD performance modeling for future space instrumentation.

Proposed method

• Utilize Robert Philbrick's trapping and emission model to describe charge transfer inefficiencies in CCDs.
• Integrate physical descriptions of radiation-induced defects in the silicon lattice into the CCD charge transfer model.
• Simulate the charge transfer process during readout using a physics-based approach grounded in semiconductor defect theory.
• Apply the model to actual STIS calibration data to compare simulated outputs with observed results.
• Adjust model parameters to minimize discrepancies between simulated and real data, refining the physical description of STIS CCD behavior.

Experimental results

Research questions

• RQ1 Can a physics-based model of charge transfer in CCDs accurately reproduce real STIS calibration data?
• RQ2 How do radiation-induced defects in the silicon lattice affect charge transfer efficiency in space-based CCDs?
• RQ3 To what extent does Philbrick's trapping and emission model explain observed charge transfer inefficiencies in STIS?
• RQ4 What are the dominant sources of uncertainty in the current physical description of the STIS CCD?
• RQ5 Can physical modeling reduce calibration errors in space-based spectroscopic instruments?

Key findings

• The physics-based model of charge transfer in STIS CCDs produces results that approximately match real calibration data.
• Radiation-induced defects in the silicon lattice significantly influence charge transfer behavior, as predicted by the model.
• The model's agreement with real data is encouraging, indicating that physical modeling can effectively describe CCD readout processes.
• Discrepancies between simulation and data highlight remaining uncertainties in the physical description of the STIS CCD.
• The approach demonstrates feasibility for improving calibration through physical modeling, even with incomplete knowledge of defect distributions.