Volume Effect (“Edge Effect”)

8/6/2019 Volume Effect (Edge Effect)

1/12

7.3.2008 Lakhdar Dehimi 1

Volume Effect

(Edge Effect)

Salim Aoulmit, Khaled Bekhouche

Lakhdar Dehimiand Andr Sopczak


2/12


Outline

Motivation

Description

Volume Effect Studies Conclusion


3/12


Motivation

The volume of the charge packet will vary with

the number of electrons contained in it, and thus

the packet will interact with a varying a fraction

of the traps within the pixel.

So the CTI depends on the volume of the traps.

Hardy paper (TNS 45,2,1998): volume effect on

width of well potential under gate [included inAM].

Here: volume effect on depth of well potential

under gate [under study for AM].


4/12


Description

The width of well potential under the gateis the same as the width of the gate.However the depth varies with the space

charge region (SCR) created in the PNjunction.

The P region is a part of the substrate and

the N region is a part of buried channel. The volume is expressed by the depth ofSCR region.


5/12


Substrate

EC (Conduction band)

Ev (Valence band)

Ef(Fermi Level)

Et1 (0.17 eV trap)Et2 (0.44 eVtrap)

Et1,2 are the trap energy levels,

EC and EV are respectively the conduction and the valence band,

Efand EFi are respectively Fermi level and intrinsic Fermi level,

wn and wp are the edges of the depletion region,

xt1,2 are the intersection points of Fermi level with trap energy level.

x

n p

wp0-wn -xt1 -xt2

V2V1

Gate

Oxide

V1: Volume of 0.17 traps

V2: Volume of 0.44 traps


6/12


Where V is the applied voltage and Vbi is the built in voltage

1, 2 and 3 are potentials in each region

Vxt is a potential at the crossing point of Fermi and trap level (-xt).

wp0-xt-wn

V+Vbi

Vxt

n p

Oxide

Gate Substrate

3(x)

2(x)

1(x)

x

(x)


7/12


8/12


21

2

12

23

3

2

2

!

xtbitVVV

qx

I

21

12

12

21

2

12

23

3

2

22

!

xtxtbinqNN

NN

N

NN

NN

N

qNw

II

21

2

12

23

2

2

2

!

xtbipN

NN

NN

N

qNw

I

tFn

bi

bi

xtEEq

!

!

i

D

C

FnnN

qkTEEE ln

2

DNN !

1

tDNNN !

2

)(3 tA

NNN !

where


9/12


Volume Effect Studies Figure show the variation of the effective volume versus

temperature for various energy levels: It effects both

amplitude and shape of CTI as function of temperature.

100 150 200 250 300 350 400 450 500 10

20

30

40

50

60

70

80

90

100

110

Temperature (K)

Effectivevolume(%)

0.1 eV

0.17 eV

0.2 eV

0.3 eV

0.4 eV

0.44 eV

0.5 eV

0.56 eV


10/12


Figure show the variation of the effective volume versus

temperature for various doping profile (ND) for 0.17 trap

100 150 200 250 300 350 400 450 500

65

70

75

80

85

90

95

10 0

Temperat re

ffecti

e

l

m

e

ND

= 2 x 1 0 15c m - 3

ND

= 4 x 1 0 15c m - 3

ND

= 8 x 1 0 15c m - 3

NA

= 1016c m

- 3

V= 5V


11/12


Figure show the variation of the effective volume versus

temperature for various doping profile (ND) for 0.44 trap

1 0 0 1 5 0 2 0 0 2 5 0 3 0 0 3 5 0 4 0 0 4 5 0 5 0 0 2 0

3 0

4 0

5 0

6 0

7 0

8 0

9 0

1 0 0

Te m

e ra t

re K

Effecti

e

l

me

%

!

"

#2 x 1 0

15cm -3

ND

= 4 x 1 0 15cm -3

ND

= 8 x 1 0 15cm -3

NA

= 1 016cm -3

V= 5 V


12/12


Conclusion Analytical model can include more parameters

which are used in the full simulation and has aneffect on the CTI .

Volume effect depends on trap levels, trapconcentration, doping profile and applied

voltage. Change of effective trap volume varies more

with 0.44 eV trap than for 0.17 eV trap as afunction of temperature.

Also larger effect for 0.44 eV traps for dopingprofile dependence.

Effect on CTI under study.

Documents

Volume Effect (“Edge Effect”)