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Durham University

Institute of Medieval and Early Modern Studies (IMEMS)

Staff and Governance

Core Staff

The day-to-day running of IMEMS is the responsibility of the Core Executive Committee, comprising the Director and Associate Directors and the Administrator. 

Publication details for Prof Brian Tanner

Lafford, T. A., Parbrook, P. J. & Tanner, B. K. (2003). Influence of alloy composition and interlayer thickness on twist and tilt mosaic in AlxGa1-xN/AlN/GaN heterostructures. Applied Physics Letters 83(26): 5434-5436.

Author(s) from Durham

Abstract

High-resolution x-ray diffraction, in surface symmetric, skew symmetric, and grazing incidence in-plane diffraction geometries, has been used to investigate the effect of an AlN interlayer between micron thick GaN and AlxGa1–xN layers grown by metalorganic vapor phase epitaxy on basal plane sapphire. No change is found in the tilt mosaic (threading screw dislocation density) with thickness or Al fraction x of the upper layer. A linear increase in the twist mosaic (threading edge dislocation density) was observed as a function of interlayer thickness and x. For all samples the twist mosaic of the AlGaN was significantly greater, by at least a factor of two, than that of the GaN layer. With increasing interlayer thickness the in-plane lattice parameter of the AlGaN decreased. The results are explained in terms of extra threading edge dislocations resulting from relaxation at the GaN/AlN interface.

References

1 R. T. Murray, P. J. Parbrook, and D. A. Wood, J. Mater. Sci. Lett. 22, 113
~2003!.
2 H. Amano and I. Akasaki, Opt. Mater. ~Amsterdam, Neth.! 19, 219 ~2002!.
3F. Natali, D. Bryne, A. Dussaigne, N. Grandjean, J. Massies, and B.
Daminterlayerano, Appl. Phys. Lett. 82, 499 ~2003!.
4 K. E. Waldrip, J. Han, J. J. Fiegel, H. Zhou, E. Makarona, and A. V.
Nurmikko, Appl. Phys. Lett. 78, 3205 ~2001!.
5 C. Pernot, A. Hirano, M. Iwaya, T. Detchprohm, H. Amano, and I.
Akasaki, Jpn. J. Appl. Phys., Part 2 39, L387 ~2000!.
6 J. Bla¨sing, A. Reiher, A. Dadgar, A. Diez, and A. Krost, Appl. Phys. Lett.
81, 2722 ~2002!.
7M. S. Goorsky and B. K. Tanner, Cryst. Res. Technol. 37, 647 ~2002!.
8T. A. Lafford, P. A. Ryan, D. E. Joyce, M. S. Goorsky, and B. K. Tanner,
Phys. Status Solidi A 195, 265 ~2003!.
9T. A. Lafford, B. K. Tanner, and P. J. Parbrook, J. Phys. D 36, A245
~2003!.
10V. Srikant, J. S. Speck, and D. R. Clark, J. Appl. Phys. 82, 4286 ~1997!.
11 D. K. Bowen and B. K. Tanner, High Resolution X-Ray Diffractometry
and Topography ~Taylor and Francis, London, 1998!, p. 252.
12P. J. Parbrook and T. Wang ~unpublished!.
13 R. Beanland, D. J. Dunstan, and P. J. Goodhew, Adv. Phys. 45, 87 ~1996!.


Full Executive Committee

Our Full Executive Committee is made up of the Core Executive Committee, listed above, plus a number of executive members including:


International Advisory Board

We are extremely fortunate to have be able to call on the help and guidance of colleagues from around the world who help to shape and guide our direction, strategy and international reach. Our current Advisory Board members are: