Novel Devices ♦ news digest


geometry is “more forgiving than bulk crystals or films, allowing you to combine materials that you normally can’t combine.”


Because the nanowires arise from a base only tens to hundreds of nanometres in diameter, they can be grown directly on silicon chips in a way that alleviates restrictions due to crystal lattice mismatch - thus yielding high-quality material with the potential for high performance.


Put these characteristics together, and it becomes possible to imagine a path from applied research to a variety of future applications. A number of significant challenges remain, however. For example, laser emission from the TUM nanowires was stimulated by light - as were the nanowire lasers reported almost simultaneously by a team at the Australian National University - yet practical applications are likely to require electrically injected devices.


Nanowire lasers: a technological frontier with bright prospects


The newly published results are largely due to a team of scientists who are beginning their careers, under the guidance of Gregor Koblmüller and other senior researchers, at the frontier of a new field. Doctoral candidates including Benedikt Mayer, Daniel Rudolph, Stefanie Morkötter and Julian Treu combined their efforts, working together on photonic design, material growth, and characterisation using electron microscopy with atomic resolution.


“At present very few labs in the world have the capability to grow nanowire materials and devices with the precision required,” says co-author Gerhard Abstreiter, founder of the Walter Schottky Institute and director of the TUM Institute for Advanced Study.


“And yet,” he explains, “our processes and designs are compatible with industrial production methods for computing and communications. Experience shows that today’s hero experiment can become tomorrow’s commercial technology, and often does.”


The papers in which this work has been described in detail are:


1) “Lasing from individual GaAs-AlGaAs core-shell nanowires up to room temperature,” by B. Mayer et al, Nature Communications, 5th Dec. 2013. DOI: 10.1038/ ncomms3931


2) “High mobility one- and two-dimensional electron systems in nanowire-based quantum heterostructures.” by S. Funk et al, Nano Letters, 25th Nov. 2013. DOI: dx.doi.org/10.1021/nl403561w


3) “Enhanced luminescence properties of InAs-InAsP core-shell nanowires,” by J. Treu et al, Nano Letters, 25th Nov. 2013. DOI: dx.doi.org/10.1021/nl403341x


This research was supported in part by the German Excellence Initiative through the TUM Institute for Advanced Study and the Excellence Cluster Nanosystems Initiative Munich (NIM); by the German Research Foundation (DFG) through Collaborative Research Centre SFB 631; by the European Union through a Marie Curie European Reintegration Grant, the QUROPE project SOLID, and the EU-MC network INDEX; by a CINECA award under the ISCRA initiative; and by a grant from Generalitat Valenciana.


Nanowire laser researchers in the laboratory: (l-r) Benedikt Mayer, Daniel Rudolph, Gregor Koblmüller, Jonathan Finley and Gerhard Abstreiter. (Photo: A. Heddergott/TUM)


Ongoing research is directed toward better understanding the physical phenomena at work in such devices as well as toward creating electrically injected nanowire lasers, optimising their performance, and integrating them with platforms for silicon photonics.


January / February 2014 www.compoundsemiconductor.net 169


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  |  Page 132  |  Page 133  |  Page 134  |  Page 135  |  Page 136  |  Page 137  |  Page 138  |  Page 139  |  Page 140  |  Page 141  |  Page 142  |  Page 143  |  Page 144  |  Page 145  |  Page 146  |  Page 147  |  Page 148  |  Page 149  |  Page 150  |  Page 151  |  Page 152  |  Page 153  |  Page 154  |  Page 155  |  Page 156  |  Page 157  |  Page 158  |  Page 159  |  Page 160  |  Page 161  |  Page 162  |  Page 163  |  Page 164  |  Page 165  |  Page 166  |  Page 167  |  Page 168  |  Page 169