Photodetectors: An Introduction to Current Technology

186 Pages·1986·8.649 MB·English

by  P. N. J. Dennis (auth.)

PHOTODETECTORS
An Introduction to Current Technology
UPDATES IN APPLIED PHYSICS AND
ELECTRICAL TECHNOLOGY
Series Editor: P. J. Dobson
Philips Research Laboratories
Redhill, England
PHOTODETECTORS: An Introduction to Current Technology
P. N. J. Dennis
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PHOTODETECTORS
An Introduction to Current Technology
P. N. J. Dennis
Royal Signals and Radar Establishment
Great Malvern, England
Plenum Press • New York and London
Library of Congress Cataloging in Publication Data
Dennis, P. N. J.
Photodetectors.
(Updates in applied physics and electrical technology)
Bibliography: p.
Includes index.
1. Photoelectronic devices. 1. Title. II. Series.
TK8304.D46 1985 681/.415 85-30066
ISBN-13: 978-1-4612-9279-1 e-ISBN-13: 978-1-4613-2171-2
DOl: 10.1007/978-1-4613-2171-2
First Printing-February 1986
Second Printing-May 1987
© 1986 Plenum Press, New York
A Division of Plenum Publishing Corporation
233 Spring Street, New York, N.Y. 10013
Text, excluding abstracts,
© 1986 Her Majesty's Stationery Office
Softcover reprint of the hardcover I st edition 1986
All rights reserved
No part of this book may be reproduced, stored in a retrieval system, or transmitted
in any form or by any means, electronic, mechanical, photocopying, microfilming,
recording, or otherwise, without written permission from the Publisher
PREFACE
This book has been written as part of a new series of scientific
text-books being published by Plenum Publishing Company Limited. The
scope of the series is to review a chosen topic in each volume, and in
addition, to present abstracts of the most important references cited
in the text. Thus allowing the reader to supplement the information
contained within this book without have to refer to many additional
publications.
This volume is devoted to the subject of Radiation Detectors,
known as Photodetectors, and particular emphasis has been placed on
devices operating in the infrared region of the electromagnetic
spectrum. Although some detectors which are sensitive at ultraviolet
and visible wavelengths, are also described. The existence of the
infrared region of the spectrum has been known for almost two hundred
years but the development of detectors specifically for these
wavelengths was limited for a long time due to technology limitations
and difficulties in understanding and explaining the phenomena
involved. Significant advances were made during World War II, when
the potential military applications of being able "to see in the dar~'
were demonstrated, and this progress has been maintained during the
last forty years when many major advances have been achieved, such
that the use of photodetectors for both civil and military
applications is now relatively common and can be inexpensive.
The two most important methods of detecting this radiation are
either by using the incident photon flux to excite carriers within a
material or by using a substance with a strongly temperature dependent
property. These different types of devices are reviewed and their
properties discussed. Finally, a comparison of typical peerformance
parameters are presented.
This book has been written such that no previous knowledge of the
subject is required, and is intended as a review of the detection
processes and presents details of current state-of-the-art
photodetectors.
v
ACKNOWLEDGEMENTS
I would like to thank my many colleagues at RSRE for all their
assistance during the preparation of this boo~. I also wish to thank
Mullard Ltd, UK for their assistance in providing the following
illustrations and photographs: Figures 4.10; 4.14; 4.17; 4.19; 4.20;
5.9; 5.12 and 5.18, GEe-Avionics Ltd and Rank Taylor Hobson UK for
their assistance in providing the photographs used in Figure 5.13, and
permission to use the following figures which are British Crown
Copyright Reserved: Figures 3.6; 3.7; 4.18; 5.13 and 5.19.
I am also grateful to Miss J Bursnell for typing this volume and
for all her patience on the numerous occasions when I have revised the
text.
P N J Dennis
vi
CONTENTS
LIST OF FIGURES
xi
CHAPTER 1
INTRODUCTION •••••••••••••••••••••••••••••••••••••••••••••..••• 1
CHAPTER 2 DETECTOR PERFORMANCE
2.1 Introduction 5
..........
..............................
2.2 Responsivity 9
2.3 Noise Equivalent Power (NEP) and Noise Equivalent
Irradiance (NEI) ••••••••••••••••••••••••••••••• 10
2.4 Detectivity ........................................ . 10
2.5 Specific Detectivity •••••••••••••••••••••••.•••..... 11
2.6 Response Time And Frequency Response 11
2.7 Spectral Response ••................................. 12
2.8 Detector Noise Sources •••••••••.••••.••••••••••.•••.. 14
2.8.1 Johnson Noise •..••••.•.•••.•............ 14
2.8.2 Generation - Recombination (G-R) Noise 15
2.8.3 Shot Noise •.•.•............•............ 16
2.8.4 Temperature Noise 17
2.8.5 11f Noise 17
2.9 S llffima ry ••••••••••••••••••••••••••••••••••••••••••••• 18
vii
viii CONTENTS
CHAPTER 3 THERMAL DETECTORS
3.1 Introduction 25
3.2 Thermopile......................................... 27
3.3 Bolometer.......................................... 29
3.4 Golay Cell .••••..•..•...••.•...•••.••..•.•...••.•.. 33
3.5 Pyroelectric Detectors ••••••••••••••••••••••••••••• 34
3.5.1 Introduction .......................... . 34
3.5.2 Detector Performance ••••••••••••••••••• 36
3.5.3 Pyroelectric Materials ••••••••••••••••• 37
3.5.4 Applica t ions .......................... . 38
CHAPTER 4 PHOTOEMISSIVE DETECTORS
4.1 Introduction 45
4.2 Principle of Operation .........•................... 46
4.3 Conventional Photocathodes ••••••••••••••••••••••••• 48
4.3.1 Metal Photocathodes •••••••••••••••••••• 48
4.3.2 Semiconducting Photocathodes ••••••••••• 49
4.4 Negative Electron Affinity Devices 52
4.5 Photoemissive Devices and Applications ••••••••••.•• 57
4.5.1 Photodiode. • • • • • • . • • • • • • • • • • • • • . • • • • • • • 58
4.5.2 The Photomultiplier •••••••••••••••••••• 61
4.6 lInagi ng Tubes ••••••••••••••.••••••••••••.•••••••••• 70
CHAPTER 5 SOLID STATE PHOTON DETECTORS
5.1 Introduction 75
5.2 Photoconductors 75
5.3 Junction Detectors 79
5.4 Metal - Insulator - Semiconductor Detectors •••••••• 84
5.5 Examples of Photon Detectors ••••••••••••••••••••••• 85
CONTENTS ix
5.5.1 Intrinsic Photoconductors 85
5.5.2 Extrinsic Detectors 93
5.5.3 Junction Detectors 96
5.6 Staring Arrays •...........•........................ 102
5.7 Applications of Photon Detectors 107
CHAPTER 6
CONCLUSIONS 109
REFERENCES 115
SELECTED ABSTRACTS 127
INDEX........................................................ 173
LIST OF FIGURES
Figure 2.1: The spectral radiant emittance of an ideal blackbody
at various t.emperatures, as a function of wavelength
in microns. 6
Figure 2.2: The total radiant photon emittance incident on a
detector up to its cut-off wavelength, as a function
of the ambient temperature. 7
Figure 2.3: The transmittance of the atmosphere for a 6000 ft.
horizontal path at sea level containing 17 mm of
precipitiable water (Gebbie et al 1951). 9
Figure 2.4: The detector response to a square wave input, defining
the detector response time T. 12
Figure 2.5: The idealised spectral response curves for a photon
and thermal detector, (a) for a constant flux per unit
wavelength interval and (b) for a constant number of
photons per unit wavelength interval. 13
Figure 2.6~ The relative contributions of noise sources for a
photoconductive detector, in the absence of any
radiation. 19
Figure 2.7: The theoretical value of D* A (peak) for a background
limited photoconductor and photovoltaic detector as a
function of cut-off wavelength, for a 2w field of view
at a temperature of 300K. • ...• 21
*
Figure 2.8: The theoretical value of D A (peak) for a background
limited photovoltaic detector as a function of the
background temperature, from 77K to 500K, for a 2rr
field of view. 22
xi