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)
L.Dehimi 29-6-2007 2
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.
L.Dehimi 29-6-2007 3
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.
L.Dehimi 29-6-2007 4
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−=
L.Dehimi 29-6-2007 5
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:
L.Dehimi 29-6-2007 6
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)
L.Dehimi 29-6-2007 7
0.17eV traps. 50MHz
L.Dehimi 29-6-2007 8
0.44eV traps. 50MHz
L.Dehimi 29-6-2007 9
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.
L.Dehimi 29-6-2007 10
Occupancy 0.17eV traps. 50MHz
L.Dehimi 29-6-2007 11
Occupancy 0.17eV traps. 25MHz
L.Dehimi 29-6-2007 12
Occupancy 0.44eV traps. 50MHz
L.Dehimi 29-6-2007 13
Occupancy 0.44eV traps. 25MHz
L.Dehimi 29-6-2007 14
Occupancy 0.44eV traps. 10MHz
L.Dehimi 29-6-2007 15
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.