Semiconductor X-Ray Detectors

Description

Identifying and measuring the elemental x-rays released when materials are examined with particles (electrons, protons, alpha particles, etc.) or photons (x-rays and gamma rays) is still considered to be the primary analytical technique for routine and non-destructive materials analysis. The Lithium Drifted Silicon (Si(Li)) X-Ray Detector, with its good resolution and peak to background, pioneered this type of analysis on electron microscopes, x-ray fluorescence instruments, and radioactive source- and accelerator-based excitation systems. Although rapid progress in Silicon Drift Detectors (SDDs), Charge Coupled Devices (CCDs), and Compound Semiconductor Detectors, including renewed interest in alternative materials such as CdZnTe and diamond, has made the Si(Li) X-Ray Detector nearly obsolete, the device serves as a useful benchmark and still is used in special instances where its large, sensitive depth is essential.

Semiconductor X-Ray Detectors focuses on the history and development of Si(Li) X-Ray Detectors, an important supplement to the knowledge now required to achieve full understanding of the workings of SDDs, CCDs, and Compound Semiconductor Detectors. The book provides an up-to-date review of the principles, practical applications, and state of the art of semiconductor x-ray detectors. It describes many of the facets of x-ray detection and measurement using semiconductors, from manufacture to implementation. The initial chapters present a self-contained summary of relevant background physics, materials science, and engineering aspects. Later chapters compare and contrast the assembly and physical properties of systems and materials currently employed, enabling readers to fully understand the materials and scope for applications.

Table of Contents

1. Introduction
   1. The Detector and Charge Sensitive Preamplifier: A System Overview
   2. The Transducer
   3. Why Semiconductors?
   4. Fermi-Dirac Statistics
   5. Doping of Semiconductors
   6. The p-n Junction Barrier
   7. Charge Generation by Radiation
   8. Pulse Height Analysis
   9. X-Ray Spectroscopy
   10. Noise
   11. Leakage Current
   12. Typical Noise Values
   13. The FET
   14. Detector Response Function F(E)
   15. Categorization of Semiconductor Detectors
   16. The Lithium Drifted Silicon Detector (Si(Li))
   17. The Silicon Drift Detector (SDD)
2. Detector Response Function
   1. The Hypermet Function
   2. Monte-Carlo Calculations
   3. Physical Processes and the Analytical Approach
   4. Peak Broadening – The Fano Factor
   5. Charge Collection Efficiency Function
   6. Generation of Spectral Response Function
   7. Charge-Loss Mechanisms
   8. Charge Gains
3. Detector Artifacts
   1. Field Distortion
   2. The Spur
   3. Non-Linearity
   4. Ghost Peaks
   5. Compton Scatter
   6. Self-Counting
   7. Absorption Edges
   8. Sum Peaks
   9. Electron Contamination
4. Contacts
   1. Metal
   2. Parameters Influencing ICC
   3. Reflection
   4. Diffused Junction Contacts
   5. Ion-Implanted Contacts
   6. Surface Barrier Contacts
   7. Low Injection Contacts
   8. Edge Termination of Contacts
   9. Radiation Damage
5. Si(Li) X-Ray Detectors
   1. Manufacture of Si(Li) Detectors
   2. The Legacy of Contouring
   3. Losing the Process
6. HPSi and HPGe X-Ray Detectors
   1. HPSi X-Ray Detectors
   2. HPGe X-Ray Detectors
   3. Performance
7. X-Ray Detectors Based on Silicon Lithography and Planar Technology
   1. Silicon p-i-n Diodes
   2. Avalanche Photo-diodes (APDs)
   3. Pixelated X-Ray Detectors (PXDs)
8. CCD-Based X-Ray detectors
   1. Introduction
   2. Techniques of Scientific CCDs
   3. The Performance of MOS-CCD X-Ray Detectors
   4. The pn-CCD
   5. CCDs Summary
9. Silicon Drift Detectors
   1. Introduction
   2. Concentric Ring SDD X-Ray Detectors
   3. Droplet SDD X-Ray Detectors
   4. SDD Performance
   5. SDD Manufacture
   6. SDD Summary
10. Wide Band-Gap Semiconductors
    1. The Candidates
    2. General Comments on WBGS
    3. The Present Status of the WBGS X-Ray Detectors
    4. Summary
11. The History of Semiconductor X-Ray Detectors
    1. Introduction
    2. The Beginnings
    3. The Development of Materials during World War II
    4. 1940-1960: Crystal Counters
    5. 1940s: The Role of National Labs, Bell Telephone Labs, and other Corporations
    6. The Story of Silicon and Germanium
    7. Other Materials
    8. 1960-66: Progress in Detector Manufacture and Spectroscopy
    9. Surface States and Nature’s Gift of SiO2
    10. Processing and Passivation
    11. 1960s: The Evolution of Detector Geometries
    12. Contacts
    13. 1960s: Lithium Compensation
    14. 1960-1966: Amplifiers
    15. 1966-71: Pulsed Optical Restore
    16. Applications on the Horizon
    17. The Companies
    18. 1970s and 1980s: Evolution in the Commercial Environment
    19. 1970s and 1980s: Low Energy EDXMA
    20. 1987: The Kevex Quantum Window: Convenience verses Performance
    21. High Purity Germanium and Silicon
    22. 1990s: HPGe X-Ray Detectors
    23. 1990s: Bespoke FETs
    24. Convenience verses Performance: A New Approach
    25. SDD: The Influence of Nuclear Physics Again
    26. SDDs as X-Ray Detectors
    27. The SDD EDXRS Companies
    28. The Future

Author(s) Description

Author of over 20 publications and the “conditioner” patent for Si(Li) X-Ray Detectors, B. G. Lowe holds a Ph.D from Liverpool University, UK. He has served as commonwealth education officer for University of Columbo, Sri Lanka; lecturer for University of Science-Malaysia, Penang, and North East Wales Institute of Higher Education, UK; chief physicist for Link Systems Ltd, London, UK; physics director, head of development, and senior scientist for Oxford Instruments, London, UK; and senior scientist for e2V Scientific, High Wycombe, UK. He also worked on the UK government-sponsored IMPACT project and CdZnTe detectors at Leicester University, UK.

Author of over 15 publications and two patents, R. A. Sareen holds a Ph.D from Manchester University, UK. He has served as research scientist for Ortec, Oak Ridge, Tennessee, USA; founder of Nuclan Ltd, London, UK; technical, managing, main board, and executive director for Link Systems Ltd, London, UK (now Oxford Instruments) and UEI London, UK; researcher at Manchester University; and shareholder in Link Systems Ltd, Gresham Power Electronics and Gresham Scientific Instruments Ltd, Salisbury, UK, and Camscan, Cambridge, UK. A Royal Microscopical Society and Institute of Physics fellow, he has liaised with several UK government departments, including security services, and participated in nuclear strategy and homeland security committees.