Development of contact technology for CdZnTe pixel radiation detectors
Lead Research Organisation:
University of Surrey
Department Name: ATI Physics
Abstract
The University of Surrey and STFC (RAL) are both leading centres for the development of semiconductor detectors for X-ray imaging and spectroscopy. In this project the student will develop new technologies for CdZnTe pixel detectors, with a particular emphasis on the study of metal-semiconductor contacts and the influence of contact performance on CdZnTe X-ray detectors. CdZnTe pixel detectors are of particular interest for hard X-ray and gamma ray imaging applications, in particular for space science and synchrotron measurements. There is a growing interest also in the COBRA double beta decay project which if selected would need a large development in high performance isotopically pure CdZnTe detectors which would benefit from this project. Both partners are actively developing CdZnTe detectors, for example through characterisation of bulk properties and the charge transport performance in CdZnTe. Both applicants are co-investigators in the RC-UK/EPSRC Basic Technology HEXITEC programme to develop CdZnTe, and have access to a wide range of CdZnTe material produced by the majority of the significant crystal growers worldwide. In order to make practical imaging detectors for STFC instrumentation we need to pattern the bulk material with arrays of electrically active, stable, small feature size electrodes. These have to control the electric field in the devices, extract the signal effectively and be electrically isolated from each other. The student will focus on developing cost effective, high performance contacts that will be stable in the typical STFC scientific environments. Increasingly the bulk properties of CdZnTe continues to improve, and the relationship between charge transport properties and detector performance is becoming better understood. However in contrast the role of metal-semiconductor contacts in CdZnTe radiation detectors is still a major topic of investigation, for example the role of non-uniform barrier height, near surface oxidation, and inter-pixel passivation. The project will therefore concentrate on the development and optimisation of various metal-semiconductor contacts for CdZnTe, which may include electroless metal deposition, and/or ion implantation techniques. The electrical performance of the contacts will be studied, and compared against different types of CdZnTe material supplied by various crystal growers. Pixel detector test structures will be fabricated, suitable for testing with RAL ASICs, and passivation methods will be developed, for example to optimise inter-pixel resistivity.
People |
ORCID iD |
Paul Sellin (Training Grant Holder) |
Publications
Allwork C
(2012)
X-Ray Beam Studies of Charge Sharing in Small Pixel, Spectroscopic, CdZnTe Detectors
in IEEE Transactions on Nuclear Science
Babar S
(2013)
An XPS study of bromine in methanol etching and hydrogen peroxide passivation treatments for cadmium zinc telluride radiation detectors
in Applied Surface Science
Bell S
(2015)
Characterization of the metal-semiconductor interface of gold contacts on CdZnTe formed by electroless deposition
in Journal of Physics D: Applied Physics
Bell S
(2013)
A multi-technique characterization of electroless gold contacts on single crystal CdZnTe radiation detectors
in Journal of Physics D: Applied Physics
Bolotnikov A
(2016)
Use of the drift-time method to measure the electron lifetime in long-drift-length CdZnTe detectors
in Journal of Applied Physics
Bolotnikov A
(2016)
CdZnTe position-sensitive drift detectors with thicknesses up to 5 cm
in Applied Physics Letters
Choubey A
(2012)
Growth by the Multi-tube Physical Vapour Transport method and characterisation of bulk (Cd,Zn)Te
in Journal of Crystal Growth
Dedic V
(2015)
De-polarization of a CdZnTe radiation detector by pulsed infrared light
in Applied Physics Letters
Duarte D
(2016)
Simulation of active-edge pixelated CdTe radiation detectors
in Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
Duarte D
(2013)
Edge effects in a small pixel CdTe for X-ray imaging
in Journal of Instrumentation
Franc J
(2013)
Flux-dependent electric field changes in semi-insulating CdZnTe
in Journal of Physics D: Applied Physics
Franc J
(2011)
Radiation induced control of electric field in Au/CdTe/In structures
in Applied Physics Letters
Franc J
(2015)
Control of electric field in CdZnTe radiation detectors by above-bandgap light
in Journal of Applied Physics
Prekas G
(2010)
Investigation of the internal electric field distribution under in situ x-ray irradiation and under low temperature conditions by the means of the Pockels effect
in Journal of Physics D: Applied Physics
Scuffham J
(2015)
Imaging of Ra-223 with a small-pixel CdTe detector
in Journal of Instrumentation
Scuffham J
(2012)
A CdTe detector for hyperspectral SPECT imaging
in Journal of Instrumentation
Seller P
(2011)
Pixellated Cd(Zn)Te high-energy X-ray instrument.
in Journal of instrumentation : an IOP and SISSA journal
Sellin P
(2010)
Electric field distributions in CdZnTe due to reduced temperature and x-ray irradiation
in Applied Physics Letters
Veale M
(2011)
An ASIC for the Study of Charge Sharing Effects in Small Pixel CdZnTe X-Ray Detectors
in IEEE Transactions on Nuclear Science
Wilson M
(2013)
Multiple Module Pixellated CdTe Spectroscopic X-Ray Detector
in IEEE Transactions on Nuclear Science
Xu Y
(2011)
Morphology evolution of micron-scale secondary phases in CdZnTe crystals grown by vertical Bridgman method
in Journal of Alloys and Compounds
Xu Y
(2012)
Investigation of Te inclusion induced glides and the corresponding dislocations in CdZnTe crystal
in CrystEngComm
Description | Basic Technology follow up grant |