Berlin 2015 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 98: Nitrides: Bulk material, films, surfaces and quantum wells

HL 98.5: Vortrag

Freitag, 20. März 2015, 10:30–10:45, EW 201

Towards an understanding of (1122) InGaN quantum wells — •Markus Pristovsek, Tongtong Zhu, Yisong Han, and Colin J. Humphreys — Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge, CB3 0FS, UK

InGaN quantum wells (QWs) are at the heart of every light emitting diode. The drop of their photoluminescence (PL) emission towards green is mostly attributed to the piezo-electric fields which separate electron and hole wave functions. Semi- and non-polar orientations are investigated since the resulting fields are strongly reduced. Especially the stable (1122) orientation offers high indium incorporation.

We have grown and characterized (1122) InGaN QWs from 400 to 600 nm and compared with (0001) QWs. The indium desorption on the (1122) is slightly higher, hence QW growth rates and temperatures have a stronger influence and indium concentration are slightly lower. The critical thickness for full relaxation was comparable to (0001).

A QW thickness series showed indeed less wavelength shift for (1122) QWs from 2.0 to 4.5 nm. However, all the wavelengths were not close to the expected positions. Furthermore, the PL intensities of all QWs were less than a third of that of simultaneously grown (0001) QWs. Systematic variation of the barrier width showed that carriers generated more than ≈3 nm away from the (1122) QWs do not contribute to the PL. Electroluminescence is currently under investigation.

We acknowledge funding from EU-FP7 ALIGHT NMP-2011-280587 and the UK EPSRC EP/I012591/1.