L.Dehimi 29-6-2007 1

Comparison of Full and Analytic Simulations

Salim Aoulmit, Lakhdar Dehimi, Achour Saadoune(LMSM Laboratory Biskra U)Craig Buttar, Dima Maneuski

(Glasgow U)Chris Bowdery, Michal Koziel, André Sopczak

(Lancaster U)

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Motivation

• Further understanding of the ISE Simulation Results (Full Simulation) for the 2-phase CP-CCD.

• Development of Analytical Model and comparison with Full Simulation.

• Studying the effect of Occupancy.• Longer term: Fast CTI determination over

a larger range of temperatures.

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Introduction• Recall: good agreement between

Analytical Model and 3-phase CCD58 Full Simulation.

• Difference between 3-phase and 2-phase: - The shift time is tsh=1/2*f- Factor of 2 (2 nodes) instead of 3 (3-nodes).

• Effect of occupancy on CTI value is introduced by correlation of waiting time and clock frequency.

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Model (ref : T. Hardy IEEE 98)

( )

packetparent he t

joincan charges which theduring periode time theis packet previous thefrom imeemission t total theis where

3

join

wemit

tt

s

t

ttt

eenNCTI eemitejoin

=

−= −− ττ

shc t<<τ

● The model considers the effect of a single trapping level and include the

emission time only in the following differential equation :

● Traps initially filled

●

trapsfilled ofdensity theis n where te

tt ndtdn

τ−=

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Hardy paper considers :

● filled traps

●

( )( )eecsh temittjoint

s

eeenNtCTI τττ −−− −−= 1*2

csht τ>>

csht τ<<Or in our case:

Analytical model is given by:

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Input Parameters

• Trap concentration: 1e11/cm3• Occupancy occ: 1% • Signal charge density Ns: 4.5e14/cm3• Frequency f: 50, 25, 10 MHz• Shift time: 1/2f• Waiting time tw: 1/(occ*f)

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0.17eV traps. 50MHz

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0.44eV traps. 50MHz

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Occupancy Study

• Simultaneous change of occupancy occand waiting time tw.

• At very high temperatures, the emission time is very short, and independent of the occupancy traps are empty when the next charge package arrives.

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Occupancy 0.17eV traps. 50MHz

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Occupancy 0.17eV traps. 25MHz

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Occupancy 0.44eV traps. 50MHz

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Occupancy 0.44eV traps. 25MHz

L.Dehimi 29-6-2007 14

Occupancy 0.44eV traps. 10MHz

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Conclusions/Outlook• CP-CCD: Glasgow and Lancaster full simulations agree

well.• For 0.17eV traps: analytical and full simulations also

agree well, and for low temperature region analytical model predicts CTI values.

• For 0.44eV traps, analytical simulations agree much better with full simulations compared to CCD-58.

• Reason: Improvement to analytical model: tjoin used for 0.44eV is larger than the one used for 0.17eV. Also improvement for CCD-58 agrrement possible.

• Occupancy study is consistent with Konstantin’s work (PhD thesis pp57-58). Further comparisons with full simulation needed.