Berlin 2012 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 61: GaN: Preparation and Characterization II (mainly structural)
HL 61.5: Vortrag
Mittwoch, 28. März 2012, 16:00–16:15, EW 202
Investigation of the influence of InGaN underlying layers on the optical properties of InGaN quantum well structures — •Mathias Müller1, Anja Dempewolf1, Frank Bertram1, Thomas Hempel1, Antje Rohrbeck1, Jürgen Christen1, Alois Krost1, Wang Lai2, Wang Jiaxing2, Wang Lei2, and Luo Yi2 — 1Institute of Experimental Physics, Otto-von-Guericke-University Magdeburg, Germany — 2Department of Electronic Engineering,Tsinghua University, Beijing, China
The optical properties of InGaN/InGaN multiple quantum wells (MQWs) with InGaN underlying layers (UL) on sapphire substrates have been comprehensively investigated by highly spatially and spectrally resolved cathodoluminescence microscopy (CL) at He temperature and by temperature dependent photoluminescence spectroscopy (PL). The Indium content of the UL was systematically varied from 1% to 4% between the samples. SEM and AFM measurements were used to examine the sample morphology. The evaluation of the temerature dependent PL measurements shows a rising activation energy of nonradiative centers with increasing In content. CL investigations of the sample surface show elongated structures in the integral intensity images and peak wavelength images, which becomes more spot-like with rising In content. The peak energy of the MQW luminescence shows a blueshift with rising In content which may be caused by a possible reduction of the quantum confined Stark effect (QCSE). At the same time the FWHM of the MQW emission is reduced from 27 meV to about 18 meV when introducing ULs.