Simulations of charge transfer in Electron Multiplying Charge Coupled Devices

Bush, Nathan; Stefanov, Konstantin D.; Hall, D.; Jordan, D. M.; Holland, Andrew D.

doi:10.1088/1748-0221/9/12/c12042

Cited by 10 publications

(10 citation statements)

References 26 publications

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“…The phenomenon may be due to carrier trapping within the dielectric layers of the device that acts to alter the potential difference between RφDC and Rφ2HV, and hence decreases the applied multiplication gain. 26,27 e2v devices are preconditioned to remove the majority of ageing effects following manufacture, but some decrease can still be observed if large signals are continually passed through the multiplication register. 26 For this testing, Device 1 was operated for longer than Device 2 in order to commission the camera system and perform additional testing following irradiation, explaining why Device 1 was observed to have aged slightly while Device 2 did not.…”

Section: Multiplication Gainmentioning

confidence: 99%

The impact of radiation damage on photon counting with an EMCCD for the WFIRST-AFTA coronagraph

et al. 2015

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WFIRST-AFTA is a 2.4m class NASA observatory designed to address a wide range of science objectives using two complementary scientific payloads. The Wide Field Instrument (WFI) offers Hubble quality imaging over a 0.28 square degree field of view, and will gather NIR statistical data on exoplanets through gravitational microlensing. The second instrument is a high contrast coronagraph that will carry out the direct imaging and spectroscopic analysis of exoplanets, providing a means to probe the structure and composition of planetary systems.The coronagraph instrument is expected to operate in low photon flux for long integration times, meaning all noise sources must be kept to a minimum. In order to satisfy the low noise requirements, the Electron Multiplication (EM)-CCD has been baselined for both the imaging and spectrograph cameras. The EMCCD was selected in comparison with other candidates because of its low effective electronic read noise at sub-electron values with appropriate multiplication gain setting. The presence of other noise sources, however, such as thermal dark signal and Clock Induced Charge (CIC), need to be characterised and mitigated. In addition, operation within a space environment will subject the device to radiation damage that will degrade the Charge Transfer Efficiency (CTE) of the device throughout the mission lifetime.Here we present our latest results from pre-and post-irradiation testing of the e2v CCD201-20 BI EMCCD sensor, baselined for the WFIRST-AFTA coronagraph instrument. A description of the detector technology is presented, alongside considerations for operation within a space environment. The results from a room temperature irradiation are discussed in context with the nominal operating requirements of AFTA-C and future work which entails a cryogenic irradiation of the CCD201-20 is presented.

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Section: Multiplication Gainmentioning

confidence: 99%

The impact of radiation damage on photon counting with an EMCCD for the WFIRST-AFTA coronagraph

et al. 2015

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“…Standard datasheet voltages were used in the simulation alongside clock rise time of 100 ns [22]. The models that handled the charge transfer process were the same as those used in [23] and are well validated [21]. The bottom panel of Figure 5 shows the charge measured beneath each of the storage phases as a function of time throughout the transfer.…”

Section: Tcad Simulation Of the Ccd201 Image Pixelmentioning

confidence: 99%

Development of in-situ trap characterisation techniques for EMCCDs

et al. 2018

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A: The "trap pumping" technique has seen considerable use over recent years as a means to probe the intrinsic properties of silicon defects that can impact charge transfer performance within CCD-based technologies. While the theory behind the technique is reasonably well understood, it has to date only been applied to relatively simple pixel designs where the motion of charge between pixel phases is fairly easy to predict. For some devices, the intrinsic pixel architecture is more complex and can consist of unequal phase sizes and additional implants that deform the electronic potential. Here, we present the implementation of the trap pumping technique for the CCD201-20, a 2-phase Teledyne e2v EMCCD. Clocking schemes are presented that can provide the location of silicon defects to sub-micron resolution. Experimental techniques that allow determination of trap energy levels and emission cross sections are presented. These are then implemented on an irradiated CCD201-20 to determine the energy level and emission cross section for defects thought to be the double acceptor state of the silicon divacancy (VV −− ) and carbon-phosphorus (C i P s ) pairs. An improvement in charge transfer performance through optimised parallel clock delay is demonstrated and found to correlate with the properties of defects found using the trap pumping technique.

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“…Ageing is an undesirable decrease of EM gain over time, attributed to injection of hot carriers into the gate dielectric and creation of defects at the Si-SiO2 interface by them. Trapped holes under P2DC or trapped electrons under P2HV decrease the effective potential difference [11], leading to lower EM gain.…”

Section: Electron Multiplying Low Voltage Ccd Withmentioning

confidence: 99%

“…Simulations with TCAD tools can reveal a great deal of information about the EM process, showing the path electrons take through the structure, the electrostatic potential, and where EM occurs [11]. Further detail can be obtained from simulations in 3D and this is essential for the visualization of the electron path.…”

Section: A Simulations Of Charge Transport In Emccdsmentioning

confidence: 99%

Electron Multiplying Low-Voltage CCD With Increased Gain

Stefanov

Dunford

Holland

2018

IEEE Trans. Electron Devices

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Novel designs for the gain elements in electron multiplying (EM) CCDs have been implemented in a device manufactured in a low voltage CMOS process. Derived with help from TCAD simulations, the designs employ modified gate geometries in order to significantly increase the EM gain over traditional structures. Two new EM elements have been demonstrated with an order of magnitude higher gain than the typical rectangular gate designs, achieved over 100 amplifying stages and without an increase in the electric field. The principles presented in this work can be used in CMOS and CCD imagers employing electron multiplication in order to boost the gain and reduce undesirable effects such as clock-induced charge generation and gain ageing.Index Terms-Electron multiplying charge coupled devices (EMCCDs), impact ionization.

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Simulations of charge transfer in Electron Multiplying Charge Coupled Devices

Cited by 10 publications

References 26 publications

The impact of radiation damage on photon counting with an EMCCD for the WFIRST-AFTA coronagraph

The impact of radiation damage on photon counting with an EMCCD for the WFIRST-AFTA coronagraph

Development of in-situ trap characterisation techniques for EMCCDs

Electron Multiplying Low-Voltage CCD With Increased Gain

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