Trap Level Spectroscopy in Amorphous Semiconductors PDF
Preview Trap Level Spectroscopy in Amorphous Semiconductors
Trap Level Spectroscopy in Amorphous Semiconductors This page intentionally left blank Trap Level Spectroscopy in Amorphous Semiconductors Victor I. Mikla and Victor V. Mikla AMSTERDAM • BOSTON • HEIDELBERG • LONDON • NEW YORK • OXFORD PARIS • SAN DIEGO • SAN FRANCISCO • SINGAPORE • SYDNEY • TOKYO Elsevier 32 Jamestown Road London NW1 7BY 30 Corporate Drive, Suite 400, Burlington, MA 01803, USA First edition 2010 Copyright © 2010 Elsevier Inc. All rights reserved No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. Details on how to seek permission, further information about the Publisher’s permissions policies and our arrangement with organizations such as the Copyright Clearance Center and the Copyright Licensing Agency, can be found at our website: www.elsevier.com/permissions This book and the individual contributions contained in it are protected under copyright by the Publisher (other than as may be noted herein). Notice Knowledge and best practice in this field are constantly changing. As new research and experience broaden our understanding, changes in research methods, professional practices, or medical treatment may become necessary. Practitioners and researchers must always rely on their own experience and knowledge in evaluating and using any information, methods, compounds, or experiments described herein. In using such information or methods they should be mindful of their own safety and the safety of others, including parties for whom they have a professional responsibility. To the fullest extent of the law, neither the Publisher nor the authors, contributors, or editors, assume any liability for any injury and/or damage to persons or property as a matter of products liability, negligence or otherwise, or from any use or operation of any methods, products, instructions, or ideas contained in the material herein. British Library Cataloguing-in-Publication Data A catalogue record for this book is available from the British Library Library of Congress Cataloging-in-Publication Data A catalog record for this book is available from the Library of Congress ISBN : 978-0-12-384715-7 For information on all Elsevier publications visit our website at www.elsevierdirect.com Typeset by MPS Limited, a Macmillan Company, Chennai, India www.macmillansolutions.com This book has been manufactured using Print On Demand technology. Each copy is produced to order and is limited to black ink. The online version of this book will show color figures where appropriate. Contents Acknowledgments vii 1 Defect States Spectroscopy in Amorphous Semiconductors 1 1.1 Introduction 1 1.2 General Principles 2 2 Thermally Stimulated Depolarization Currents in Amorphous Chalcogenides 21 2.1 Background 21 2.2 Theoretical Background 23 2.3 TSDCs in Se-Based Amorphous Semiconductors: Experimental Results 28 2.4 TSDC in Pure Selenium 29 2.5 TSDC in As(Sb)x Se 1 (cid:2) x Alloys 31 3 Carrier Transport Processes in Amorphous Solids 37 3.1 Background 37 3.2 Experimental Techniques for the Measurement of Carrier Mobility 39 3.3 Significance of Carrier Transport Data in Various Applications 42 3 .4 Conventional Dispersion Behavior 43 3.5 Anomalous Dispersive Characteristics 44 4 Time-of-Flight Experiments in Amorphous Chalcogenide Semiconductors 53 4.1 An Apparatus for IFTOF Measurements 56 4.2 XTOF Technique 61 4.3 TOF Measurements in Selenium-Based Amorphous Multilayer Photoconductors 6 6 5 Xerographic Spectroscopy of States in Mobility Gap 79 5.1 Schematic Overview of the Xerographic Photocopying Process 80 5.2 Xerography in Animation 83 5.3 Xerographic Dark Decay and Photoinduced Effects 85 vi Contents 6 Photoinduced Effects on States in the Mobility Gap 95 6.1 Introduction 95 6.2 Steady-State Photocurrents 9 5 6.3 Light-Induced Effects on Photocurrent Transients 9 6 7 Spectroscopic Studies of Gap States and Laser-Induced Structural Transformations in Se-Based As-Free Amorphous Semiconductors 103 7.1 Preparation of Amorphous Films: Essential Results and Interpretation 103 7.2 The Basic Properties 105 7.3 Dark Discharge 107 7.4 Transient Photoconductivity 108 7.5 Photoinduced Discharge Characteristics 109 7.6 Optical Properties 114 7.7 Structural Transformation 116 Acknowledgments I would like to express my sincere thanks to Lisa Tickner (Elsevier), Lisa Jones (Elsevier), and Mani Prabakaran (MPS Limited) for their patience, continued inter- est, and helpful comments, which have made it possible for this book to reach completion. U ndoubtedly, without the inspiration of my wife, Ottilia, this material could never have become a book. Victor I. Mikla Uzhgorod March 2010 This page intentionally left blank 1 Defect States Spectroscopy in Amorphous Semiconductors Contents 1.1 Introduction 1 1.2 General Principles 2 1.2.1 Basic Types of Relaxation Techniques 2 1.2.2 The Principle of Detailed Balance and Classification of Trapping States 2 1.2.3 Trap Level Spectroscopy: Experimental Methods 5 1.2.4 Direct Methods 6 1.2.5 Indirect Methods 6 1.2.6 TSL and TSC: Retrospective Glance 7 1.2.7 Defect States in Semiconductors and Insulators 9 1.2.8 Field-Induced Thermally Stimulated Currents 10 1.2.9 Remarks on TSC/TSL 12 1.1 Introduction Amorphous semiconductors are characterized by properties that are absent in their crystalline counterparts. On the one hand, they are “u nsuitable” objects both for experimentalists and from the theoretical point of view; on the other hand, they have widespread technical applications. Therefore, trap level spectroscopy in materials containing S, Se, and Te is necessary for further technical applications. Currently, there is no universal technique that probes the full spectrum of trapping levels in a mobility gap; experimentalists use several complementary methods. This book is devoted to techniques that probe states in the mobility gap and the results of their use. The book is an encyclopedia in the sense that it gives “ starting ” information about a wide range of spectroscopic techniques in disordered materials. The author only provides brief, annotated descriptions of these techniques, their advantages, and experimental results that are typical for the objects considered. Trap Level Spectroscopy in Amorphous Semiconductors. DOI:10.1016/B978-0-12-384715-7.00001-2 Copyright © 22001100 by Elsevier Inc. All rights of reproduction in any form reserved.
The list of books you might like
