Speaker
Ms
Victoria Boothman
(University of Surrey)
Description
Ring-drift design has been applied for the first time to large (6mm) CZT detectors for hard x-ray spectroscopy. The detectors have also been modelled with Sentaurus TCAD, a powerful 3D tool. Our aim is to determine the electrode geometry and bias conditions that optimise energy resolution and sensitivity.\\
These devices are intended as a high-resolution room temperature photon detector for X-rays in the range 50-500keV. Drift designs operate as single-carrier detectors, sensitive only to electron transport throughout the active region. This overcomes the problem of poor hole transport in II-VI and other compound semiconductors. Our prototype cadmium zinc telluride (CZT) drift detector achieved resolution of 4.53 keV FWHM at an energy of 59.54 keV, limited predominantly by the electronic noise of our preamplifier system.
A previous study of CZT drift detectors [1] demonstrated complex variations in sensitivity with interaction position, biases and energy. The spatial response of our new CZT device was mapped by synchrotron microbeam scanning in order to investigate performance and charge transport variations over the surface area of the detector. Our data show that the detector performance is sensitive to optimal bias combinations and that the lateral 'drift' field exerts a crucial influence on active area, peak position and sensitivity.
Line scans were simulated in 3D with Sentaurus TCAD. A model of CZT material with realistic charge deposition and transport properties was first developed. The insight gained into fields and charge motion will be discussed. Energy shift and change in sensitivity with beam position matched experimental data, validating the model. Simulations will be repeated with varying geometry and bias conditions in search of optimum performance.
[1]A. Owens et al., “Hard X-ray response of a CdZnTe ring-drift detector”J. Appl.Phys., vol.102, no.5, pp 0545055
Author
Ms
Victoria Boothman
(University of Surrey)
Co-authors
Mr
Aied Alruhaili
(University of Surrey)
Dr
Annika Lohstroh
(University of Surrey)
Dr
Kawal Sawhney
(Diamond Light Source)
Prof.
Paul Sellin
(University of Surrey)
Dr
Slava Kachkanov
(Diamond Light Source)
Dr
Veeramani Perumal
(University of Surrey)
