Dresden 2014 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 13: Nitrides: Optical characterization

HL 13.3: Vortrag

Montag, 31. März 2014, 11:45–12:00, POT 251

Optical characterization of quaternary AlInGaN SQW using cathodoluminescene spectroscopy — •Martin Müller1, Christopher Karbaum1, Gordon Schmidt1, Frank Bertram1, Jürgen Christen1, Jan Wagner2, Michael Jetter2, and Peter Michler21Institute of Experimental Physics, OvGUniversity Magdeburg, Germany — 2IHFG, Stuttgart University, Germany

The optical properties of quaternary AlInGaN SQW have been investigated using spectrally and time-resolved cathodoluminescence (CL) microscopy at liquid helium temperature. All samples of the set consist of an 1 µ m thick optimized GaN buffer on a c-plane sapphire substrat. Subsequently, on top of this a quaternary SQW of varying thickness (2, 3, 6, 10 nm) was grown using pulsed MOVPE and finally capped by a high temperature GaN layer. At low temperatures the CL-spectra are dominated by a blue-shifted near band edge luminescence with respect to relaxed GaN and a broad quaternary SQW emission band at about 370 nm. A slight shift of the SQW emission band to longer wavelengths with increasing thickness possibly caused by the quantum confined Stark effect as a consequence of inherent electric fields could be clearly seen. Addionally, the initial lifetime of the SQW increases from 1.1 ns up to 1.5 ns with the thickness as a result of a decreased electron and hole wave function overlap. The temperature dependent shift of the FXA and FXB from the GaN buffer could be observed indicating a high optical quality. The non-Varshni-like shift of the quaternary SQW emission with temperature will be discussed.

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