Dresden 2009 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 11: Focused Session: Semi- and nonpolar group III nitrides I

HL 11.3: Topical Talk

Dienstag, 24. März 2009, 10:45–11:15, HSZ 01

Growth and characterisation of planar (11-20) and (11-22) GaN-based multiple quantum well structures — •Menno Kappers — Department of Materials Science and Metallurgy, Pembroke Street, University of Cambridge, Cambridge, CB2 3QZ, UK

The effects of polarisation charges observed in polar (0001) GaN-based heterostructures can be eliminated or reduced by growing on the non-polar (11-20) and semi-polar (11-22) planes, respectively. This may result in improvements to the recombination efficiency in QW structures where the reduced overlap between the electron and hole wavefunctions caused by electric fields leads to long radiative lifetimes. However, planar non- and semi-polar GaN-based structures grown on sapphire substrates are burdened by a high defect density, which are possible sources of non-radiative recombination that compromises the predicted high IQE of QW structures. Indeed, great advances in device efficiencies have been made by a few groups around the world using non- and semi-polar GaN bulk substrates with very low dislocation densities. The challenge for the rest of us is to improve the quality of hetero-epitaxial GaN-based structures. Some have chosen to study heterostructures on non- and semi-polar facets grown on basal-plane substrates, others prefer the growth of planar epilayers on R- and M-plane sapphire. Part of the combined research efforts at the Universities of Cambridge and Manchester is to find methods of defect reduction in planar (11-20) and (11-22) GaN and the structural and optical characterization of GaN/AlGaN and InGaN/GaN MQW structures. An up-to-date overview of our research progress will be given.