Growing Graphene on Semiconductors

Growing Graphene on Semiconductors edited by Nunzio Motta Francesca Iacopi Camilla Coletti

Growing Graphene on Semiconductors

Growing Graphene on Semiconductors edited by Nunzio Motta Francesca Iacopi Camilla Coletti

Published by Pan Stanford Publishing Pte. Ltd. Penthouse Level, Suntec Tower 3 8 Temasek Boulevard Singapore 038988 Email: editorial@panstanford.com Web: www.panstanford.com British Library Cataloguing-in-Publication Data A catalogue record for this book is available from the British Library. Growing Graphene on Semiconductors Copyright 2017 by Pan Stanford Publishing Pte. Ltd. All rights reserved. This book, or parts thereof, may not be reproduced in any form or by any means, electronic or mechanical, including photocopying, recording or any information storage and retrieval system now known or to be invented, without written permission from the publisher. For photocopying of material in this volume, please pay a copying fee through the Copyright Clearance Center, Inc., 222 Rosewood Drive, Danvers, MA 01923, USA. In this case permission to photocopy is not required from the publisher. ISBN 978-981-4774-21-5 (Hardcover) ISBN 978-1-315-18615-3 (ebook) Printed in the USA

Contents Preface ix 1. The Significance and Challenges of Direct Growth of Graphene on Semiconductor Surfaces 1 N. Mishra, J. Boeckl, N. Motta, and F. Iacopi 1.1 Introduction 1 1.2 Direct Growth of Graphene on Si Substrates 3 1.2.1 Laser Direct Growth 4 1.2.2 Carbon Ion Implantation 5 1.2.3 MBE Growth 7 1.3 Thermal Decomposition of Bulk SiC 7 1.4 Graphene on Silicon through Heteroepitaxial 3C-SiC 10 1.4.1 Thermal Decomposition of 3C-SiC on Si 10 1.4.2 Metal-Mediated Graphene Growth 12 1.5 Conclusions 15 2. Graphene Synthesized on Cubic-SiC(001) in Ultrahigh Vacuum: Atomic and Electronic Structure and Transport Properties 27 V. Yu. Aristov, O. V. Molodtsova, and A. N. Chaika 2.1 Introduction 27 2.2 Synthesis of Few-Layer Graphene 28 2.2.1 Methods of Graphene Fabrication 28 2.2.2 Growth of Cubic-SiC Epilayers on Standard Si Wafers 31 2.2.3 Synthesis of the Epitaxial Graphene Layers on (111)- and (011)-Oriented Cubic-SiC Films Grown on Si Wafers 32 2.3 Synthesis and Characterization of Continuous Few-Layer Graphene on Cubic-SiC(001) 34 2.3.1 Step-by-Step Characterization of SiC(001) Surface during Graphene Synthesis in Ultrahigh Vacuum 35

viii Contents 2.3.2 Atomic and Electronic Structure of the Trilayer Graphene Synthesized on SiC(001) 41 2.3.3 Influence of the SiC(001)-c(2 2) Atomic Structure on the Graphene Nanodomain Network 53 2.4 Nanodomains with Self-Aligned Boundaries on Vicinal SiC(001)/Si(001) Wafers 55 2.4.1 LEEM and Raman Studies of Graphene/SiC(001)/4 -off Si(001) 55 2.4.2 Atomic and Electronic Structure of the Trilayer Graphene Synthesized on SiC(001)/2 -off Si(001) 56 2.4.3 Transport Gap Opening in Nanostructured Trilayer Graphene with Self-Aligned Domain Boundaries 59 2.5 Conclusions 63 3. Graphene Growth via Thermal Decomposition on Cubic SiC(111)/Si(111) 77 B. Gupta, N. Motta, and A. Ouerghi 3.1 Introduction 77 3.2 Epitaxial Growth of Graphene 78 3.2.1 Thermal Graphitization of the SiC Surface 78 3.2.2 Graphene Growth on Cubic SiC(111)/ Si(111) 80 3.3 Surface Transformation: From 3C-SiC(111)/ Si(111) to Graphene 82 3.3.1 Reconstructions of SiC(111) 82 3.3.1.1 Si-terminated face 82 3.3.1.2 C-terminated face 83 3.3.2 LEED and LEEM Characterization of the Transformation 85 3.3.3 STM Characterization: Atomic Resolution Imaging of the Transition 89 3.3.4 Atomic Structure Studies of Bi- and Multilayer Graphene 92

Contents ix 3.3.5 Improving the Epitaxial Graphene Quality by Using Polished Substrates 96 3.4 Conclusion 99 4. Diffusion and Kinetics in Epitaxial Graphene Growth on SiC 109 M. Tomellini, B. Gupta, A. Sgarlata, and N. Motta 4.1 Introduction 109 4.2 Evolution of Epitaxial Graphene Films as a Function of Annealing Temperature 111 4.2.1 Evaluation of the Growth Rate in UHV 114 4.3 Growth Kinetics of Epitaxial Graphene Films on SiC 116 4.3.1 Growth Kinetics under Ar Pressure 116 4.3.2 Growth Kinetics in UHV 117 4.3.3 Si and C Diffusion Process 118 4.3.4 Kinetic Model of Graphene Layer-by- Layer Formation 121 4.3.5 Kinetics of Graphene Islands with Constant Thickness 127 4.3.6 Alternative Kinetic Models 132 4.3.6.1 Terrace growth model 132 4.3.6.2 Disk growth model 134 4.4 Conclusion 135 5. Atomic Intercalation at the SiC Graphene Interface 141 S. Forti, U. Starke, and C. Coletti 5.1 The Interface Layer 142 5.2 Hydrogen Intercalation 144 5.2.1 How It Works 144 5.2.2 Technical Details 144 5.2.3 Quasi-Freestanding Monolayer Graphene 145 5.2.4 Quasi-Freestanding Bilayer Graphene: Seeking a Bandgap 148 5.2.5 The ABC of Quasi-Freestanding Trilayer Graphene 151 5.2.6 Hydrogen Intercalation at the 3C-SiC(111)/Graphene Interface 156

x Contents 5.2.7 Hydrogen Intercalation: Impact and Advances 157 5.3 Intercalation of Different Atomic Species 158 5.3.1 The Intercalation of Ge Atoms at the Graphene/SiC Interface 160 5.3.2 Electronic Spectrum of a Graphene Superlattice Induced by Intercalation of Cu Atoms 163 5.4 Conclusive Remarks 169 6. Epitaxial Graphene on SiC: 2D Sheets, Selective Growth, and Nanoribbons 181 C. Berger, D. Deniz, J. Gigliotti, J. Palmer, J. Hankinson, Y. Hu, J.-P. Turmaud, R. Puybaret, A. Ougazzaden, A. Sidorov, Z. Jiang, and W. A. de Heer 6.1 Introduction 182 6.2 Near-Equilibrium Confinement-Controlled Sublimation Growth 183 6.2.1 Multilayer C Face 185 6.2.2 Monolayer C Face 188 6.2.3 Monolayer Si Face 190 6.3 Selective Graphene Growth 192 6.3.1 Masking Techniques 192 6.3.2 Sidewall Facets 194 6.4 Large-Scale Integration 198 6.5 Conclusion 199 Index 205

Contents xi Preface Graphene, the wonder material of the 21st century, has not yet achieved the expected outcomes in terms of applications in nanoelectronics. This is not surprising, as large-scale graphene growth is still mostly limited to CVD on metallic foils, followed by graphene transfer to the semiconductor substrate required for electronic devices, which is cumbersome and difficult to automatize. Moreover, graphene is gapless, and this is still seriously limiting its applications. This book is an attempt to dispel this pessimistic outlook, summarizing the latest achievements in the direct growth of graphene on semiconductors. SiC is the ideal semiconductor for graphene growth, which is typically achieved by thermal graphitization. Through hightemperature annealing in a controlled environment, it is possible to decompose the topmost SiC layers, obtaining quasi-ideal graphene by Si sublimation. Graphene on SiC with record electronic mobilities has been demonstrated, opening the way for applications in nanoelectronics, by exploiting selective growth on patterned structures and gap opening by quantum confinement. The book opens with a chapter on the significance and challenges of graphene growth on semiconductors, by Mishra et al., drawing a picture of the perspectives of this technology. The three following chapters, by Aristov et al., Gupta et al., and Tomellini et al., respectively, are dedicated to an up-to-date analysis of the synthesis of graphene on SiC in ultrahigh vacuum. The fifth chapter, by Forti, Starke, and Coletti, is a review of the effect of atomic intercalation at the SiC graphene interface, with an in-depth discussion of the doping effects and of the electronic properties of lateral superlattices. The sixth chapter, written by the de Heer and Berger group, reporting graphene growth on SiC by sublimation, summarizes the whole history of graphene growth on SiC by confined controlled sublimation, up to the latest developments in the growth of templated graphene nanostructures.

xii Preface We hope that this book can be of inspiration to the many scientists striving to improve the growth of graphene on semiconductors and to the young researchers from industry and academia approaching this fascinating world. The developments sketched here show a promising outlook for the future, with many exciting outcomes on the horizon, from the artificial opening of a gap to the creation of 2D field-effect transistors with nanodimensions. Nunzio Motta Queensland University of Technology, Australia Francesca Iacopi University of Technology Sydney, Australia Camilla Coletti Istituto Italiano di Tecnologia, Italy