new research activity “silicon detectors modeling in rd50”: goals, tasks and the first steps

New research activity “Silicon detectors

modeling in RD50”: goals, tasks and the first steps

Vladimir EreminIoffe Phisical – technical institute

St. Petresburg, Russia

Motivation

1. The practical goal of RD50 – engineering of semiconductor radiation hard detectors

2. The detector engineering is based on: – Physical study– Microscopic and macroscopic data– Physical models– Mathematical calculations (original and industrial packages)

3. Development of common understanding on- the modeling procedure and cross-test the software

V.Eremin, RD50, Nov 2011

1. Input data systematization:•microscopic properties of irradiated silicon,•transport properties of irradiated silicon,•parameterization of the effects.

2. Development of physical models for simulation•reverse current,•electric field,•current pulse response,•CCE,

3. Evaluation systematization and interpretation of the experimental results with the developed models4. Data base for input data, parameterizations, results of the modeling and key experimental results.

The main tasks

One goal and Two approaches

Microscopic approach

Gray Box

software

Microscopic properties

Detector parameters

Numerical calculation


+parameterizati

on

Detector parameters

Phenomenological model

Phenomenological approach


Recombination phenomenon description in DESSIS simulator

From: Petasecca M., et al., “Numerical simulation of radiation damage effect in P-Type silicon” RD50 workshop, June 2005.


Numerical calculation


+parameterizati

on

Detector parameters

Phenomenological model

Linear models for major fluence dependent microscopic properties:

Concentration of current generated levels is proportional to fluence

Trapping probability is proportional to fluence

SRH statistics for the occupancy of radiation induced levels

Phenomenological approach

Parameterization/approximation of: Bulk generation current via SHR statistics Trapping time (from experiment)

Solution of 1D equations set : Poisson Continuity Occupancy equations

Detector parameters: Electric field distribution (V, F, T), CCE (V, F, T) for PAD detector and with Ramo’s weighting electric field then CCE (V, F, T) for strip detector along the strip axes


Jgen ~ Nmgl* σ *exp(-Emgl/kT)

Nmgl = Σ (F x Gmgli) ~ fluence

Fluence dependence of reverse current

A striate line fit of J(F) is a strong argument to use a linear dependences of the radiation induced defects concentration on F.


1.E-03

1.E-02

1.E-01

1.E+00

1.E+01

1.E+02

1.E+03

1.E+04

3.0E-03 3.5E-03 4.0E-03 4.5E-03 5.0E-03

1/T, K-1

I, u

AComparison of 1 level and 2 levels models

for bulk generated current

__ PTI 1 effective level model__ Perugia V-V level model__ Perugia 2 levels model__ V-V from Perugia 2 levels model Experiment from I(F) plot

F = 4.2 e13 neq/cm3


0,0025 0,0030 0,0035 0,0040 0,004510

-5

10-4

10-3

10-2

10-1

100

Fn = 1*10

12 cm

-2

experiment fit:

single level two levels

I, A

1/T, K-1

0,0030 0,0035 0,0040 0,0045 0,0050 0,005510

-5

10-4

10-3

10-2

10-1

100

101

Fn = 4.2*10

13 cm

-2

1/T, K-1

0,0035 0,0040 0,0045 0,0050 0,005510

-4

10-3

10-2

10-1

100

101

102

Fn = 2.3*10

14 cm

-2

1/T, K-1

Fn, cm-2 11012 4.21013 2.31014

Ea, eV 0.685 0.649 0.620

6.1E-01

6.2E-01

6.3E-01

6.4E-01

6.5E-01

6.6E-01

6.7E-01

6.8E-01

6.9E-01

1.0E+12 1.0E+13 1.0E+14 1.0E+15

Neutron fluence, cm-2

Cu

rre

nt

ac

tiv

ati

on

en

erg

y, e

V

Reverse current at different fluences in neutron irradiated detectors

V.Eremin, RD50, Nov 2011 0 50 100 150 200 250 300

0,0

0,2

0,4

0,6

0,8

1,0 Normalized spectraDL11

= 1-1.5 k

#; Fn, cm

-2:

D99; 1.7*1013

D100; 3.75*1014

D123; 2*1015

DL

TS

sig

na

l, a

rb.

un

its

T, K

Trapping probability

A. Bates and M. Moll, NIM A 555 (2005) 113–124

1 = 1/τ0 + σ*Vth*Ntr = F

Trapping probability (protons)

1/te0, [s-1] 3x10-3

βe 3.2x10-7

1/th0, [s-1] 3x10-3

βh 3.5x10-7


D ???

May be MGA is a trapping center for holes??

Where is hole trapping center?

Estimation: at F=1e15neq/cm3, Nmgl = 1e15 1/cm3:Vth=1e17 cm-2 and Trapping cross-section = 1e-14cm2 and τ = 10 ns,instead of 3 ns.


P+ N+

Neff(F)

+_

Electric field evolution with fluencein Hamburg model

Space Charge Sigh Inversion (SCSI)Fscsi ~ 1e13 n/cm2E(x)

x

F = 0


Detector signal at high proton fluence

High proton fluence, 24 GeV, 7·1014 cm-2, p+ side: DP shape, peaks become equal

E. Verbitskaya et al., 5 RESMDD, Florence, Oct 10-13, 2004 V.Eremin, RD50, Nov 2011

Simulation of TCT pulse and E(x)

E. Verbitskaya et al., 5 RESMDD, Florence, Oct 10-13, 2004

Parameters derived from fits

Protons 24 GeV, Fp = 6.91014 cm-2

Carrier trapping considered

p+ side

p+

179 V 218 V 268 VW1 (mkm) 90 65 60Wn (mkm) 18 15 8W2 (mkm) 192 220 232Eb 1250 1800 2600Neff1 1.83E+12 2.53E+12 6.03E+12Neff2 4.65E+12 4.24E+12 4.24E+12


PTI model for electric field distribution in irradiated detectors

V. Eremin, E. Verbitskaya, Z. Li. “The Origin of Double Peak Electric Field Distribution in Heavily Irradiated Silicon Detectors”, NIM A 476 (2002) 556.

trapping

-V

Trapping of free carriers from detector reverse current to midgap energy levels of radiation induced defects leads to DP E(x)

DLs responsible for DP E(x) are midgap DLs:

DD: Ev + 0.48 eV

DA: Ec – (0.52 – 0.595) eV

Neff


Simulated electric field in irradiated detector in the frame of

PTI model

0.E+00

1.E+07

2.E+07

3.E+07

4.E+07

5.E+07

6.E+07

7.E+07

8.E+07

0.00 0.01 0.02 0.03 0.04 0.05

Distance from p+, cm

Co

nc

en

tra

tio

ns

, cm

-3

n(x)

p(x)

-3.E+13

-3.E+13

-2.E+13

-2.E+13

-1.E+13

-5.E+12

0.E+00

5.E+12

1.E+13

2.E+13

2.E+13

0.00 0.01 0.02 0.03 0.04 0.05


Co

nce

ntr

atio

ns,

cm

-3

Neff

0.0E+0

5.0E+3

1.0E+4

1.5E+4

2.0E+4

2.5E+4

3.0E+4

3.5E+4

4.0E+4

0 0.01 0.02 0.03 0.04 0.05


Ele

ctri

c fie

ld, V

/cm

E(x)

F=1e15, V=400V, d=300 um, T=260K

MGL parameters in the PTI model


Hot problems

• Why the reverse current activation energy is sensitive to fluence?

• Which level is responsible for trapping?• Revision of experimental data for detector properties: J(F, T,

radiation), τ(F),• PF effect at high E and the trapped carriers emission efficiency,• Comparison of E(x) simulated by EXL and TCAD for planar

detector• Cross sections for the MGLs and their introduction rates.

Steps forward

1. Current parameterization2. Trapping time parameterization3. Adjust TCAD for 1D modeling of E(X) (boundary conditions

on the left and right edges,4. Cross tests TCAD with not professional softwares.

List of participants and tasks

Institution Package1 Package2 Ir(T,F) Ttr (V, F) {E(x)}(F)Ioffe PTI,

St. Petersburg

Original, EXL

TCAD TCT, alphas

TCT, response reconstruction

Thank you for your attention and for

suggestions on the project

new research activity “silicon detectors modeling in rd50”: goals, tasks and the first steps

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