# Presentation: 240417

##    Ultra-rad-hard Sensors for Particle Physics Applications 

**Li**
**Brookhaven National Laboratory**
**On behalf of CERN RD50 Collaboration**

**          ****Pixel 2002, September 9-12, 2002, Carmel, CA**** ****  **

## RD50 – 271 members

**RD50 – 271 members**

## RD50 – 52 institutes

**RD50 – 52 institutes**

##      OUTLINE

- Introduction
- Radiation induced defects levels in Si
- Radiation induced degradation of electrical properties in Si detectors
**	****	****Leakage current**
**	****	**** ****Changes in electrical neutral bulk**
**	****	****Space charge transformations  and CCE loss**
- RD 50’s approaches to obtain ultra radiation hardness
**	****	****Material /impurity / defect engineering (MIDE)**
**	****	****Device structure engineering (DSE)**
**	****	****New materials**
- Future tasks to be carried out by RD 50
- Summary

## Introduction

**Introduction**

- LHC

- L

- =

- 10

- 34

- cm

- -

- 2

- s

- -

- 1

- 

- ( R=4cm)

- ~

- 3·10

- 15

- cm

- -

- 2

- 10 years

- 

- (

- R

- =75cm)

- ~

- 3·10

- 13

- cm

- -

- 2

- Technology available, however serious radiation damage will result

- lt.

- Possible up

- -

- grade

- L

- =

- 10

- 35

- cm

- -

- 2

- s

- -

- 1

- 

- ( R=4cm)

- ~

- 1.6

- ·10

- 1

- 6

- cm

- -

- 2

**A**

**focused and coordinated R&D effort is mandatory to develop  reliable and**

** **

**cost**

**-**

**effective radiation hard HEP detector technologies for such radiation**

**levels  ---- ****The approval and formation of CERN RD50 Collaboration (6/02)**

- Dedicated radiation hardness studies also beneficial before a luminosity upgrade

- Radiation hard technologies now adopted have not been completely

- characterized:

- Oxygen

- -

- enriched Si in ATLAS pixels

- A deep understanding of radiation damage will be fruitful also for the

**linear **

**collider**

- where high doses of e,

- 

- will play a significant role.

## CERN RD50

**CERN RD50**

**Development of Radiation Hard Semiconductor Devices for Very High Luminosity Colliders**

## Slide 7

## Radiation induced degradation of electrical

**Radiation induced degradation of electrical**
**properties in Si detectors**

## Parameterization of Leakage current

***J***** ****= ***********eq***

*********: leakage current constant***

***Annealing behavior:***

*********(t)= ************I ******·exp(-t/************I ******)+***
***+ ************0****** -************ · ln(t/t******0******)***

*********0****** = -9x10******-17****** A/cm+4.6x10******-14****** /T******a******  AK/cm***
*** ******t******0******=1 min***

*** ******1/ ************I******= k******0I ******exp(-E******I******/k******B******T******a ******)****** ***

*** ******k******0I ******=1.2 ******x10******-18****** ******/s, E******I******=1.1 eV****** ***

*********I ******=1.2x10******-17****** A/cm***
*********=3.1x10******-18****** A/cm***

*** *****M. Moll, Ph.D. Thesis, University of Hamburg, 1999**

## Bulk Damage (electrical neutral bulk, ENB)

**Si bulk resistivity increases with fluence and saturates near the intrinsic**
**value of about 300 k ********cm**

**B. Dezillie et al., IEEE Trans. Nucl. Vol. 46, No. 3, (1999) 221 **

**S. Pirollo et al., NIM A426 (1999) 126-130 **

## Space charge transformations  and CCE loss

**Space charge transformation (SCT) takes one of the following **
**three forms:**

**Space charge becomes more negative with radiation**
**	****due to the creation negative deep acceptors **
**(As-irradiated effect)**
**Space charge sign inversion (SCSI) or “type inversion”**
**Increase in full depletion voltage (V****fd****) due to increase of net**
**space charge density V****fd****  =                         CCE loss at a given bias**
**Increase of space charge density during annealing at RT and**
**	****elevated temperatures ****(“Reverse annealing”)**
**More increase of V****fd**
**Space charge modifications due to trapping by**
**      ****free carriers ****	**

##  = 0.1/Nd0

**Donor removal:**

**The removal rate is not a constant**

**-**

****** ****= 0.1/*****N******d0***

- 1011

- 1011

- 1012

- 1013

- 1013

- 1015

- 1014

- 1013

- 1015

- 1012

- 1014

- 1016

## Reverse Annealing

**Reverse Annealing**

**RT annealing**

**ET annealing**

**Neutron**

**Neutron**

**Proton**

**G.Lindstroem, presented on "1st Workshop on Radiation hard semiconductor devices for very high luminosity colliders", CERN 28-30 November, 2001**

## Parameterization of Neff 

**(As-irradiated and reverse annealing)**

***N******eff***** ****= *****N******eff0 ******-************ N******eff***

********* ******N******eff ******= ******N******A****** ******+ ******N******C****** ******+ ******N******Y ***

*** ******N******Y ******: Reverse annealing***

*** ******N******A ******: Beneficial annealing***

*** ******Stable defect***

***g******Y ******=0.0516 cm******-1***

*** ****** ******Stable acceptor***

*** ******N******C ******= N******C0 ******(1-e******-c************eq******) + g******C****** ************eq ***

*** ******N******C0 ************ 0.7xN******d0***

*** ******Removable donor***

- 0

*** ******N******Y ******= N******Y,************ ******(1- 1/(1+t/************Y ******))****** ***

*** ******1/ ************Y ******= k******0,Y ******exp(-E******Y******/k******B******T******a ******)****** ***

***E******Y***** =1.33 eV**
***k******0,Y *****=1.5x10****15**** /s**

*** ******N******A ******= N******A0****** exp(-t/************a ******)****** ***

*** ******g******a ******=0.018cm******-1***

*** ******1/ ************a ******= k******0,a ******exp(-E******aa******/k******B******T******a ******)****** ***

***E******aa***** =1.09 eV**
***k******0,Y *****=2.4x10****13**** /s**

***c****** ******=0.1/N******d0***

*** *****M. Moll, Ph.D. Thesis, University of Hamburg, 1999**

## Model for the reverse annealing

**Z. Li et al., IEEE Trans. Nucl. Sci., Vol. 44, No. 3, (1997) 834  **

** ****Reverse annealing in ****n****, ****p****, ****alpha**** irradiated Si detectors**
**   ****(****Clusters****)**
** ****No reverse annealing in ****gamma**** irradiated Si **
**   ****(Single defects only, ****no clusters****)**
** ****Reverse annealing may be due to the**
**   ****breaking off of clusters over time and temp,**
**    ****releasing single defects:**
**	****Clusters             V-V or related defects**
**  **

**Releasing**

**Single defects**

## Double-Junction/Double-Peak (DJ/DP) Effect

**DJ/DP effect and the 2-deep level model ****(Z. Li and H.W. Kraner, J. Electronic Materials, Vol. 21, No. 7, (1992) 701)**

**1.7x10****14**** n/cm****2****, **
**Laser on p****+**
**(D. Menichelli et al., NIM A426 (1999)135-139)**

## Detail Modeling of (DJ/DP) Effect

**Detail Modeling of (DJ/DP) Effect**

**2-deep level model**** ****(V. Eremin et al, ****Nucl. Instrum. & Meth. **_**A476**_** (2002) 556-564. **** )**

**Increasing V**

**Increasing V**

## Degradation in Charge Collection Efficiency (CCE)

**Degradation in Charge Collection Efficiency (CCE)**

**Depletion **
**Volume term**

**Trapping term**

## Radiation Hardness

** ****Impurities ****intentionally**** incorporated into Si may serve to ****getter**
**radiation-induced vacancies to prevent them from forming the**
**damaging V-V and related centers**
** ****Impurities: ****O, Sn, N, Cl, H,**** etc. **

**One example: oxygen O:**

**Competing processes for V**

**If [O] >>[V] and [V-O], then the formation rates of  V****2**** and V****2****O will be**
** ****greatly suppressed:**

**Key: impurity concentration should be much larger than that of vacancies**

**Material/ impurity/defect Engineering (MIDE)**

## Material/ impurity/defect Engineering (MIDE)

**Reactions**

-  **       ****B. MacEvoy, 3****rd**** ROSE Workshop 12-14 Feb 98**

**Material/ impurity/defect Engineering (MIDE)**

## Defect structure modeling 

**for n-rad**

**Defect structure modeling **

## Defect kinetics modeling 

**Both V****2**** and V****2**** O productions are greatly suppressed in oxygenated Si**** **

## Material/ impurity/defect Engineering (MIDE)

**               ****Oxidation+long time diffusion in N****2**** at high T**** ****(up to 1150 ****°****C)**
**              ****[O****i****] ****up to 5·****10****1****7****cm****-3**
**              ****developed in the framework of RD48**** in ****1998**

**Material/ impurity/defect Engineering (MIDE)**

_**HTLT**_** : High Temperature Long Time oxidation **** **
**               ****Oxidation in straight O****2**** at high T (up to 1200 ****°****C) for up to 24 hrs**** **
**              ****[O****i****] ****up to 4·****10****1****7****cm****-3****, uniform up to 50 ********ms.**
**              ****d****eveloped ****at BNL in ****1992**

**Review of Current Technologies**

_**Advanced HTLT**_** : High Temperature Long Time oxidation **** **
**               ****Oxidation in straight O****2**** at high T (up to 1200 ****°****C) for up to 216 hrs**** **
**              ****[O****i****] ****up to 4·****10****1****7****cm****-3****, uniform up to 400 ********ms.**
**              ****d****eveloped ****at BNL in ****1999**
**	**
**  ****Thermal donor (TD) suppression (no change in initial doping)**
**  ****TD introduction (initial doping dominated by TD)**

## Little improvement with regard to neutron radiation by HTLT

**B. Dezillie et al., IEEE Trans. Nucl. Sci., Vol.  , No. , (2000) 1892-1897  **

**Little improvement with regard to neutron radiation by HTLT**

**Maximum improvement with regard to gamma radiation by HTLT**

## Oxygenation  partially improve charged particle (p,  ) radiation hardness

**Oxygenation **** **_**partially**_** improve ****charged particle (p, ******** )**** radiation hardness**
**By a factor of 2-3**

**Thermal donor are not removed:**
**delay of SCSI**

## Model for the role of oxygen in rad-hardness

| Particle type | Single defects | Defect clusters | 
Oxygen effect
 |
| --- | --- | --- | --- |
| n | x | xxxxxx
RV-V>>1 | No |
| Charged particles (p, , etc.) | xxxx
RV-V <<1 | xx
 | 
Partial

 |
|  | xxxxxx
RV-V <<1 |  | Yes |

**1000 V’s**

**3 O’s**

**Z. Li et al., Nucl. Inst. & Meth., A461 (2001) 126-132  **

**The local [O] is much smaller than [V] within the cluster**

## Material/ impurity/defect Engineering (MIDE)

**Low resistivity starting Si materials**
**   ****Delayed SCSI**
**   ****Lower *****V******fd***** at higher fluences**

**Nucl. Inst. Meth. A360 (1995) 445**

## Oxygen Dimers in Silicon

**Oxygen Dimers in Silicon**

* **neutral ?*

**Thinner Detectors**

**S. Watts et al., presented at Vertex 2001**

**More radiation tolerance:**
**         ****For d = 50 ********m, the detector can be still fully depleted up to a**
**         ****fluence of 2-3x10****15**** n/cm****2**** at bias of 200 V:**
**  ****For a low starting resistivity Si (50 ********–cm), no SCSI up to **
**                  ****1.5x10****15**** n/cm****2**** **
**  ****For high starting resistivity Si (******** 4 k********-cm), still fully **
**    ****depleted up to 3x10****15**** n/cm****2**** , even though SCSI taking place**
**    ****at about 1x10****13**** n/cm****2****.**

**Oxygen dimer O****2i**** formed during pre-irradiation by Co****60**** ********-irradiation at 350****o****C**

## Device Structure Engineering (DSE)

** ****Multi-guard-ring system (MGS)**

-  **To increase the detector breakdown voltage**
**  ****High operation voltage to achieve more radiation tolerance**
**  ****Up to ****1000 volts**** can can be achieved (up to ****6x10****14 ****n/cm****2**** tolerance)**
**  ****Both CMS and ATLAS pixel detector systems use MGS**

**JHU**

** ****n on n**** and ****n on p**** detectors**

-  **Not sensitive to SCSI**
**  ****Both CMS and ATLAS pixel detector systems use ****n on n**

**p****+**** back**
** ****side**

**MGS**

**n****+**** pixel**

## Multi-guard-ring system (MGS)

**G. Bolla et al., NIM A435 (1999) 178 **

##  Differ from conventional planar technology, p+ and n+ electrodes are

**Sherwood I. Parker et al., UH 511-959-00**

-  **Differ from conventional planar technology, p****+**** and n****+**** electrodes are**
**    ****diffused in small holes along the detector thickness (****“3-d” processing****)**
**  ****Depletion develops laterally (****can be 50 to 100 ********m****): ****not sensitive to thickness**
**  ****Much less voltage used --- much higher radiation tolerance**

## Other Novel Structures

***p******+******-****** ******n******+****** /n/p******+****** configuration***
***      ******(low resistivity)***

***Two-sided process***

***-***

## Other Novel Structures

***p***

***+***

***-***

***n***

***+***

***/n/n***

***+***

***configuration***

***(Medium resistivity)***

- •

**Low bias at the beginning**

- •

**p**

**+**

**-**

**n**

**+**

**/n/n**

**+**

**configuration:**

- o

**Depletion from one side before SCSI**

- o

**Depletion from both sides after SCSI**

- •

**May work up to 1x10**

**15**

**n/cm**

**2**

**rad.**

- •

**One sided processing**

- •

**Bias **

**Vb**

**may be larger than **

**Vf **

**to get maximum depletion depth without break down**

**Z. Li, 9**

**th**

**Vienna Conference on Instrumentation, Vienna, Austria, February**

**19**

**-**

**23, 2001**

***p******+******-****** ******n******+****** /n/n******+****** configuration***
***   ******(Medium to high***
***  ******resistivity)***

***Single-sided process!***

**Other Novel Structures**

##                       New Materials

**                      ****New Materials**

**Other semiconductor materials may have to be used for extremely high radiation  (****>1x10****16**** n/cm****2**** ) **
**Diamond, SiC, etc.**

## Future RD50 Tasks

** ****More studies in the fields of:**
** ****MIDE --- O and other impurities: H, Cl, N, oxygen-dimer, etc.**
** ****DSE --- Realize 3D and semi-3D detectors, and thin detectors**
**   ****(push rad-hardness/tolerance to a few times of 1x10****15**** n/cm****2****)**
** ****Make detectors with combined technologies:**
**Oxygenated detectors with MGS and/or  3D and novel detector **
**   ****structures**
**Oxygenated low resistivity detectors with MGS and/or 3D and novel detector structures**
**And so on**
**(push rad-hardness/tolerance close to 10****16**** n/cm****2****)**
** **
** ****Other semiconductor materials for extremely high radiation **
** ****SiC, etc.**
**(push rad-hardness/tolerance over 1x10****16**** n/cm****2****)**

## Summary

** ****Different particles cause different displacement damage in Si material and detectors**
** ****Radiation-induced damages cause detector electrical properties to**
**degrade: **
** ****increase of detector leakage current**
** ****compensation of Si bulk (intrinsic bulk resistivity)**
** ****increase of negative space charge during radiation and annealing**
** ****space charge maybe modified by charge trapping**
** ****To obtain ultra high Radiation hardness/tolerance, newly-formed CERN RD50 Collaboration is poised to carry out various tasks**
** ****Material/impurity/defect engineering**
** ****Device structure engineering **
** ****Detector operation and modeling **
** ****Full detector integration**
** ****Other semiconductor materials for extreme radiation (> 10****16**** n/cm****2****)**** **

**1****st**** RD50 - Workshop on R****adiation hard semiconductor devices ****for very high luminosity colliders, ****CERN 2-4 October, 2002**
**http://rd50.web.cern.ch/rd50/1st-workshop/default.htm**