CONNECTING THE COMPOUND SEMICONDUCTOR COMMUNITY
October 2012 Volume 18 Number 7
Editor Dr Richard Stevenson
richardstevenson@angelbc.co.uk +44 (0)1291 629640
Contributing Editor Dr Rebecca Pool
News Editor
Dr.Su Westwater
editorial@rebeccapool.com suwestwater@angelbc.co.uk
Director of Solar & Semiconductor Publishing Jackie Cannon
+44 (0)1923 690205
Senior Sales Executive Robin Halder
+44 (0)2476 718109
Sales Manager Shehzad Munshi +44 (0)1923 690215
USA Representatives Brun Media Tom Brun
Tel: 724 539-2404 Janice Jenkins
Tel: 724-929-3550
Director of Logistics Sharon Cowley
+44 (0)1923 690200
Design & Production Manager Mitchell Gaynor
+44 (0)1923 690214
Circulation Director Jan Smoothy
+44 (0)1923 690200
Subscriptions Manager Debbie Higham
+44 (0)1923 690220
Chief Operating Officer Stephen Whitehurst
stephen.whitehurst@angelbc.com +44 (0)2476 718970
Directors
Bill Dunlop Uprichard – CEO Stephen Whitehurst – COO Jan Smoothy – CFO Jackie Cannon, Scott Adams, Sharon Cowley, Sukhi Bhadal
Published by
Angel Business Communications Ltd, Hannay House, 39 Clarendon Road, Watford, Herts WD17 1JA, UK T: +44 (0)1923 690200 F: +44 (0)1923 690201
Angel Business Communications Ltd Unit 6, Bow Court, Fletchworth Gate, Burnsall Road,Coventry CV5 6SP T: +44 (0)2476 718 970 F: +44 (0)2476 718 971
Compound Semiconductor is published eight times a year on a controlled circulation basis. Non-qualifying individuals can subscribe at: £105.00/€158 pa (UK & Europe), £138.00 pa (air mail), $198 pa (USA).Cover price £4.50. All information herein is believed to be correct at time of going to press. The publisher does not accept responsibility for any errors and omissions. The views expressed in this publication are not necessarily those of the publisher. Every effort has been made to obtain copyright permission for the material contained in this publication. Angel Business Communications Ltd will be happy to acknowledge any copyright oversights in a subsequent issue of the
publication.Angel Business Communications Ltd © Copyright 2012. All rights reserved. Contents may not be reproduced in whole or part without the written consent of the
publishers.The paper used within this magazine is produced by chain of custody certified manufacturers, guaranteeing sustainable sourcing.
US mailing information: Compound Semiconductor, ISSN 1096-598X, is published 8 times a year, Jan/Feb, March, April/May, June, July,August/September, October,November/ December by Angel Business Communications Ltd, Unit 6, Bow Court, Fletchworth Gate, Burnsall Rd,Coventry CV5 6SP.
UK.The 2012 US annual subscription price is $198. Airfreight and mailing in the USA by agent named Air Business Ltd, c/o Worldnet Shipping Inc., 156-15, 146th Avenue, 2nd Floor, Jamaica, NY 11434, USA. Periodicals postage paid at Jamaica NY 11431. US Postmaster: Send address changes to Compound Semiconductor, Air Business Ltd, c/o Worldnet Shipping Inc., 156-15, 146th Avenue, 2nd Floor, Jamaica, NY 11434, USA.
Printed by: Pensord Press. ISSN 1096-598X (Print) ISSN 2042-7328 (Online) © Copyright 2012.
Substrates made from wide bandgap materials are far less mature, sell for significantly higher prices, and often contain more imperfections. But quality will improve as crystal growers refine their technologies and equipment manufacturers introduce new tools to scrutinise substrates.
One metrology firm that has recently produced tools for inspecting SiC substrates is LaserTec. Its pieces of equipment feature the combination of confocal microscopy and differential interferometry, and they are claimed to expose incredibly shallow scratches and small pits on the sample surface (see page 30 for details).
Although this tool will help to increase the quality of SiC substrates – they can exhibit a variety of defects, including those with esoteric names, such as triangles and carrots – the biggest opportunity for improvement lies with GaN. Dislocations in typical substrates number more than a million per square centimetre, and it appears that the only way to bring this figure down by several orders of magnitude is to turn to a new technology for forming boules.
One attractive option that can banish dislocations has recently been unveiled by researchers at Osaka University, Japan (see page 53). Engineers begin by taking a film of GaN grown on sapphire, placing a sapphire substrate with millimetre-sized apertures on top, and inserting this combination in a stainless steal tube. This is filled with a metal melt of gallium, sodium and carbon, plus nitrogen gas at a pressure of 3.6 MPa. GaN seeds form in the apertures, and can grow and coalesce to yield high-quality, defect free crystals. So far, these are only a few millimetres in size, but the Japanese engineers have set their sights on producing 8-inch material.
If they succeed, this could revolutionize GaN substrate manufacture. And in the meantime, as they build devices on their small pieces of dislocation-free GaN, they will answer a question that has intrigued and evaded us for many years: How much better is a GaN device when it is built on a perfect foundation? I’ll leave you to ponder the answer to that.
Dr Richard Stevenson Editor
October 2012
www.compoundsemiconductor.net 3
debbie.higham@angelbc.com
The devices with the fewest defects are underpinned with the most established substrates – GaAs and InP. The
material quality of both of these platforms is incredibly high, and today’s manufacturers of these products focus on improving yield and bringing down cost, rather than developing revolutionary technologies for boule growth.
jan.smoothy@
angelbc.com mitch.gaynor@
angelbc.com sharon.cowley@
angelbc.com
You can see this happening in many different situations, from the sandcastles that I built with my family this summer to the vast array of compound semiconductor devices developed and manufactured by our community.
shehzad.munshi@
angelbc.com robin.halder@angelbc.com Improving the foundations E:
tbrun@brunmedia.com E:
jjenkins@brunmedia.com
GREAT FOUNDATIONS underpin great structures. And when they are not there, what you build can rapidly deteriorate, with cracks and defects appearing before the entire structure finally falls apart.
jackie.cannon@
angelbc.com
editorialview
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84 |
Page 85 |
Page 86 |
Page 87 |
Page 88 |
Page 89 |
Page 90 |
Page 91 |
Page 92 |
Page 93 |
Page 94 |
Page 95 |
Page 96 |
Page 97 |
Page 98 |
Page 99 |
Page 100 |
Page 101 |
Page 102 |
Page 103 |
Page 104 |
Page 105 |
Page 106 |
Page 107 |
Page 108 |
Page 109 |
Page 110 |
Page 111 |
Page 112 |
Page 113 |
Page 114 |
Page 115 |
Page 116 |
Page 117 |
Page 118 |
Page 119 |
Page 120 |
Page 121 |
Page 122 |
Page 123 |
Page 124 |
Page 125 |
Page 126 |
Page 127 |
Page 128 |
Page 129 |
Page 130 |
Page 131