CVD Diamond Neutron Detectors

Transcription

Arnaldo Galbiati
30 October 2009
Arnaldo Galbiati
Diamond Detectors Ltd
CVD Diamond
Neutron Detectors
1

Properties of Diamond

Diamond Detectors

CVD Diamond Neutron Detectors

Introduction to DDL
30 October 2009
Arnaldo Galbiati
Diamond Neutron Detectors
2
1920
1940
1950 – 60
1962
1970
1980
Diamond demonstrates UV response
Diamond used to detect ionising nuclear radiation
Interactions of Alpha and high energy fast electrons with diamond studied
Photoconductivity of Natural Diamond investigated
Advances made in forming electrical contacts to diamond
Commercial x-ray dosimeters for medical applications
Early 90’s Advances made in quality of polycrystalline CVD diamond (pCVD)
pCVD recommended for use in Super Conducting Super Collider
Employed as commercial solar blind UV detector.
Late 90’s Beam position monitors for synchrotrons
Charge Collection distance > 200 µm
Many high energy physics detector applications.
2000
2002
2006
2007
2008
Diamond as a detector is not a new technology and as early as
1920's highly selected natural diamonds were being used for
UV detectors. The recent commercial availability of high purity
single crystal diamond with excellent bulk uniformity is
however a new development.
DeBeers Industrial Diamond patents manufacturing procedure for High purity single crystal
diamond with superior electronic characteristics
DeBeers Industrial Diamond forms Element Six
E6 perfects volume manufacturing process for electronic grade” materials
DDL formed by Element Six
DDL patents metallisation development
DDL achieves surface polishing improvements <1nm roughness
DDL 50% acquired by BAE Systems
Diamond Detectors Limited
3
30 October 2009
Diamond Detectors
4
Diamond radiation detectors are able to detect deep
UV photons, X-rays, gamma rays, electrons, alpha
particles, charged ions and neutrons, with a
dynamic range in energies spanning from 5.5 eV up
to GeV of cosmic rays.
Since the bandgap of diamond is 5.5 eV this leads
into a negligible dark current noise at room
temperature with no need for cooling.
Arnaldo Galbiati
Diamond tetrahedron
(from www.pdymorf.net/matter14.htm)
Phase Diagram for Carbon
F.P. Bundy, The P,T Phase and Reaction diagram for elemental Carbon, 1979; J. Geophys. Res. 85 (B12) (1980) p. 6930
Why use Diamond?
Radiation hardness -> no frequent
replacements
High mobility of free charges-> Fast response
Compact volume solid state detector
Room temperature operation-> No Cooling
Resistivity ~5 orders of magnitude > Silicon
Low leakage current -> No need for pn
junction
30 October 2009
Intrinsic Material Properties
9
Why use Diamond?
The special characteristics of diamond allow its use in
extreme
environmental
conditions
like
high
temperature, high radiation, and highly corrosive
environments.
Hence, its use for example in:
High energy physics as Beam Condition Monitor and
particle tracker at CERN,
As a radiotherapy dosimeter
In X-ray synchrotron radiation monitoring (e.g., ESRF,
Grenoble, France)
as UV and neutron detector at the Joint European
Torus, Culham, U.K.
First Radiation Detectors (1945)
From Natural Diamond
At that time counting properties were found to be
uncontrollable, depending upon the crystal and the type
of radiation.
Furthermore, charge polarization occurred, leading to a
progressive reduction in both counting rate and pulse
amplitude as a function of the time of irradiation.

P.J. VAN HEERDEN, Thesis Utrecht, 1945.

R. HOFSTADTER., Phys. Rev. 73 (1948) 631.

Since 1970, the attractive properties of diamond for
radiation detection were demonstrated by KOZLOV et
al. from mono-crystalline diamond stones of extremely
high electronic quality.

Alpha Particle Detection
History in Diamond
Kaneko et al. 2003
Bergonzo et al., Diamond and Related Materials, Volume 10, Issues 3-7, March-July (2001),
631-638
High Purity Single Crystal CVD Diamond:
100 % charge collection efficiency

100 % counting detection efficiency

0.4-1 % energy resolution (Alpha 5 MeV)

sc CVD Diamond Detectors
J.H. Kaneko et al. 2003l
Reference Figure from: J.H. Kaneko et al. / Nuclear Instruments and Methods in Physics Research A 505 (2003) 187–190
Commercially Available High Purity Single Crystal CVD Diamond:
100 % charge collection efficiency

100 % counting detection efficiency

0.4-1 % energy resolution (Alpha 5 MeV)

No pumping (priming) effects

Long term stability

sc CVD Diamond Detectors
Radiation Detection in Diamond
Diamond radiation detectors are generally designed as a
parallelepiped solid-state ionization chamber.
A charged particle, or a photon with energy above the bandgap,
passes through the diamond and ionizes it (energy to form e-h
pair: 13 eV) generating electron–hole pairs, which are separated
by the electric field between the electrodes.
Fast neutrons are detected directly in the bulk of the intrinsic
diamond layer through the 12C (n,α) 9Be and 12C (n,n')12C*
reactions*.
The produced 9Be and α ions have a total energy:
Eα + Βe = Εn – 5.7 MeV where Εn is the energy of the impinging neutron.
•To detect both fast and thermal neutrons a layer of 6LiF or 10B
allows the conversion of low energy neutrons into highly ionizing
particles.
•
*M. Pillon, M. Angelone, A.V. Krasilnikov, Nucl. Instr. and Meth. Phys. Res. B 101 (1995) 473.
Diamond intrinsic high efficiency
for fission neutron detection
•Diamond has the highest atomic density of any material
•This translates into a high neutron efficiency
per unit volume.
•“Diamond appears to have the highest intrinsic
efficiency for fission neutron detection per unit
thickness, and hence per unit volume”*.
* G .J. S c h m i d et al . / N u c l ear I n str u m en ts an d M eth o d s i n P h y si c s R esear c h A 527 (2004) 554– 561
G .J. S c h m i d et al . / N u c l ear I n str u m en ts an d M eth o d s i n P h y si c s R esear c h A 527 (2004) 554– 561
Diamond intrinsic high efficiency
Diamond experimental efficiency
“Based on the diamond neutron data, along with the
total neutron yields as acquired via as sociated particle
counting, it is poss ible to extract experimental values for
the intrinsic efficiency per unit thickness , and to compare
this to calculation. For our diamond s ens or, with an
energy thres hold of ~20– 30 keV (estimated carbon
recoil energy), the experimental efficiency values at
2.5 and 14 MeV are 2.2 and 2.4%/mm respectively”*
At 14.1 and 14.9 MeV, the spectrum shape is due to a combination of elastic scattering, inelastic scattering, and
(n ,a) reactions, as discussed theoretically by Pillon
[M. Pillon, M. Angelone, A.V. Krasilnikov, Nucl. Instr. and Meth. Phys. Res. B 101 (1995) 473.]
*G .J. S c h m i d et al . / N u c l ear I n str u m en ts an d M eth o d s i n P h y si c s R esear c h A 527 (2004) 554– 561
Bergonzo et al.
http://www-norhdia.gsi.de/talks/4th/G_Verona-Rinati.pdf
Single crystal CVD diamond neutron detectors in a p-type/intrinsic/metal layered structure - Gianluca Verona-Rinati, Uni Roma Tor Vergata
Diamond Detector
14 MeV Neutron Spectroscopy
LiF Layer Thickness
6
Almaviva et al. J. Appl. Phys. 103, 054501 2008
Diamond Neutron Detectors Counting Sensitivity under thermal irradiation
Diamond Detector
14 MeV Neutron Spectroscopy
14 MeV Neutron pulse
sc CVD Diamond Detector+DBA (2GHz amplifier)
ANGELONE et al.: “NEUTRON DETECTORS BASED UPON ARTIFICIAL SINGLE CRYSTAL DIAMOND IEEE TRANSACTIONS ON NUCLEAR SCIENCE”, VOL. 56, NO. 4, AUGUST 2009
DBA-IV (2GHz Broadband Amplifier)
•The DBA-IV 2GHz Broadband amplifier is available through www.diamonddetectors.com
Diamond Neutron Detectors
Tested at Frascati Neutron Generator and JET
Neutron Diamond Detectors
new ENEA-DDL collaboration
“The benefits to industry in Europe of working with JET
are more than simply the value of the contracts
received. The technologies developed can have
applications also in other fields. A recent example is a
detector made of artificial diamond developed by the
Italian Association ENEA for measuring the number
and energy spectrum of neutrons emitted from the
JET plasma.” Lorne Horton, JET Insight June 2009.
CVD Diamond History
Introduction to DDL
DDL Proprietary Contact Technology
30 October 2009
Diamond Detectors
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Introduction to DDL
JJune 2007, DDL Moves into new office, Poole, Dorset
PPress release Thursday 3rd May 2007
“Element Six Spins Out New Company to Develop Diamond Detectors…….
22008, BAE systems acquires 50% share in DDL
30 October 2009
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Diamond Detectors focus includes...
•
Diamond Wide Band Gap Detectors. (solid state
ionizing chamber)
•
Diamond Sensors (Electro-chemical and Bio
applications).
High Tech Application of Diamond
Introduction to DDL
Facilities
Expertise
Diamond Lab
Laser Lab
Chemistry Lab
Lithography and Assembly Clean
rooms. (class 1000 & 10000)
Design Suite
30 October 2009
Material Processing
Lapping & Polishing Processes
Laser Dicing & Shaping
Metallization (e.g. Ti, Pt, Au, Al..)
Neutron Scintillation Coating 6LiF
Lithography (sandwich,strips,pixels)
Die Fabrication and Test
Die/Wire Bonding.
Packaging
Characterisation.
Electronics Development
“From Concept through Design & Prototype to Manufacture”
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Introduction to DDL
Concept - Design
30 October 2009
Manufactured Devices
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Introduction to DDL
ball bonding (K&S 4124)
Aluminium & Gold wedge and ball
wire bonding
Dage 4000 Wire bond pull tester
Universal wedge bonder (K&S
4523)
Optical Profiler NT9100
Semi Automatic Scaife
Metallisation
44
30 October 2009
Sputtering & E-Beam
Evaporation & Milling
Magnetron Sputtering
Quazer Laser Dicing
Laser cutting, dicing & sputtering system
Wire Bonding (Strip Detector)
Lapping, Polishing and Semi-automatic scaife
Device Fabrication
Introduction to DDL
Characterisation
Typical process specifications :Polycrystalline standard polish Ra < 20nm
Polycrystalline detector polish Ra < 12nm
Polycrystalline Super polish
Ra < 5nm
Single crystal detector polish Ra < 1nm
30 October 2009
Electronic / Device Characterisation
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•Ultra high purity CVD Diamond
•Less than 5 ppb Boron and Nitrogen impurities
Intrinsic Polycrystalline
Up to 12 cm diameter wafers
Electronic grades of CVD diamond produced
Intrinsic single crystal
Standard 4.7mm square
Standard 4.7mm square
© 2008 Diamond Detectors Ltd
Example :- Diamond Radiation Detector
Module as COB (Chip on Board) with electrical metal posts
(photo-realistic rendering by Solidworks softrware)
Single Crystal Diamond Radiation Detector
Standard Module [25mm Diameter] with SMA connector
Diamond Radiation Detector
Beam Conditions Monitor
Quadrant Detector
Example :- Diamond Radiation Detectors in BNC and TO-Metal Can
(electrodes bonded from lateral sides not top and bottom)
Diamond Dimensions
5 x 1 x 0.5 mm
e.g.: directional information
with robust electrical point contacts
Module with SMA and Chip in Board packaging
Single Crystal Diamond Radiation Detectors
Standard size: 4.7 x 4.7 x 0.5 mm

Can be laser cut and mechanically polished to create customized sizes
and shapes, and or assembled in a mosaic or stack structure

Available standard thickness 50 μm to 500 μm

Minimum active volume size 1 x 1 x 0.5 mm

Standard electrical contact shapes
(square and circle)

Customised electrical contact shapes

DDL proprietary contact

(photo-realistic rendering by Solidworks softrware)
Customised electrical contact materials

Standard Module [25mm Diameter] with SMA connector
CVD Diamond History
Introduction to DDL
30 October 2009
Diamond Detectors
55
(Electrical Contact Fabrication on CVD Diamond)
Metallization
Diamond Detectors Limited (DDL) has patented an innovative metallization technique to maximize CVD diamond
performance. Here we seek to highlight the issues and describe the solution.
The development of CVD Diamond has made possible many new applications for detecting and sensing. However,
manufacturing semiconductor devices in diamond present some interesting challenges due to diamond’s unique
characteristics. Traditional or inadequate contact fabrication may result in poor mechanical adhesion, polarization
effects and unrepeatable results.
Mechanical Adhesion
Specifically, the mechanical adhesion of the metal chosen as electrode on the diamond surface. A flatter smoother surface
presents fewer adhesion points. When a metal is thermally evaporated on diamond it may not adhere and it could peel off
after a short period of time with the consequent deterioration of the electrical signal measured and therefore a decrease in
the lifetime of the device. Mechanical adhesion is a function of the diamond / contact interface.
Polarization Effects
Polarization phenomena occur when electric currents pass through diamond if the electrical contact is not able to extract
and inject electrons fast enough. In this case, the neutrality of the crystal after the passage of ionizing nuclear radiations is
not restored in the time interval between two consecutive events. As a result, charge accumulation occurs within the crystal
and immobile carriers establish an electric field which acts in a direction opposite to the applied field produced by the
external bias voltage V. The minimisation of polarization effects requires optimal injecting contacts.
Repeatable Results
If a device is to be commercially viable it should be consistent and stable in a variety of environmental conditions. Requires
stable and resilient contacts.
Historically, there have been three main approaches to fabricate good electrical contacts on diamond:
1. Damaging the diamond surface in order to disrupt the sp3 bonding.
2. Using carbide forming metals like titanium or chromium to create a hybrid metal-diamond interface material .
3. Doping of diamond during growth or using ion implantation.
For example, to prepare good injecting contacts, several metals were used by Kozlov et al., for hole injection they used Ag,
Au, Pt or C deposition, aluminium or boron implantation, for electron injection P, Li or C.
Galbiati et al. IEEE TNS VOL 56 N 4 AUGUST 2009 p1863
Metallization
Metallization
DDLs solution
To address the polarization issues mentioned above and to provide a method for forming an ohmic electrode that is also
durable and stable for applications in diamond radiation detectors and diamond electronics, Diamond Detectors Ltd have
developed and tested an innovative electrical contact using a very thin diamond like carbon layer. Diamond-like carbon
(DLC) is a form of amorphous carbon between diamond and graphite, containing significant portion of sp3 bonded atoms in
the matrix. DLC films can be grown when carbon is deposited under energetic (~10-100eV) bombardment, where the
instantaneous local high temperature and pressure induce a proportion of carbon atoms to bond as diamond. The
conditions for DLC deposition are obtained during a variety of methods, including CVD, laser ablation, magnetron sputtering,
cathodic arc, and ion beam deposition.
This innovative contact consists of a very thin (1-3 nm) diamond-like carbon film which is formed on a diamond substrate by
means of Argon magnetron sputtering from a carbon target. The very thin DLC layer allows for the injection of both holes
and electrons in the diamond substrate. Also, the DLC layer becomes a seed for the sputter deposition of high work function
noble metals (Pt, Au) which allow metals to cohere to the diamond surface. As platinum and gold have a higher work
function than diamond this permits electrons present at the diamond surface to be driven towards the noble metals via
quantum mechanical tunnelling through the thin DLC layer acting as a quantum mechanical tunnelling junction.
DDL’s patented metallization technique provides a manufacturable, high adherence diamond / contact interface with
minimal polarization effect while maximizing stability and contact resilience.
58
Dark Current Characteristics
59
Collaborating Opportunities ?
 Custom design and prototype manufacture.
Let us help you develop a resilient detector/sensor
technology for your application using our design
tools, facilities and experience in collaboration with
your R&D team.
 Prototype to Product (cost engineering, batch
processing and test)
60
Conclusion
High quality electronic CVD diamond radiation detectors are
now readily available.
DDL has made significant investment to ensure we have the
ability and tools to manufacture diamond prototypes leading
to standard products for a range of applications including high
energy physics, medical, civil nuclear and oil and gas.
DDL will continue to support the development of diamond
applications with the aim to provide a range of standard
products with datasheets.
30 October 2009
61
30 October 2009
Thank you
62
REFERENCES:
Bergonzo et al., Diamond and Related Materials, Volume 10, Issues 3-7, March-July (2001), 631-638
J.H. Kaneko et al. / Nuclear Instruments and Methods in Physics Research A 505 (2003) 187–190
Pomorski et al., Phys. Stat. Sol. (a) 202, No. 11 (2005)
Gianluca Verona-Rinati “Single crystal CVD diamond neutron detectors in a p-type/intrinsic/metal layered
structure” , http://www-norhdia.gsi.de/talks/4th/G_Verona-Rinati.pdf
Galbiati et al. “Performance of Monocrystalline Diamond Radiation Detectors Fabricated Using TiW, Cr/Au
and a Novel Ohmic DLC/Pt/Au Electrical Contact” IEEE TNS VOL 56 N 4 AUGUST 2009 p1863
Angelone et al.: “NEUTRON DETECTORS BASED UPON ARTIFICIAL SINGLE CRYSTAL DIAMOND”
IEEE TRANSACTIONS ON NUCLEAR SCIENCE, VOL. 56, NO. 4, AUGUST 2009 pp.2275-2279
Almaviva et al.: “Thermal and fast neutron detection in chemical vapor deposition
single-crystal diamond detectors” J. Appl. Phys. 103, 054501 2008
G.J. Schmid et al. “A neutron sensor based on single crystal CVD diamond”,
Nuclear Instruments and Methods in Physics Research A 527 (2004) 554–561
M. Pillon, M. Angelone, A.V. Krasilnikov, Nucl. Instr. and Meth. Phys. Res. B 101 (1995) 473.

CVD Diamond Neutron Detectors

Transcription

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