AlInN/GaN based multi quantum well structures - growth and optical properties

High indium content ([In>]25%) AlInN/GaN multi quantum well structures grown by metal organic vapor phase epitaxy were analyzed by X-ray diffraction, X-ray reflection, and photoluminescence measurements. The samples, which exhibit an excellent crystalline quality and smooth interfaces, are found to show broad luminescence below the GaN-bandgap which shifts with increasing indium content to longer wavelength. At elevated indium content an additional broadening of the luminescence band has been observed. A comparison of the AlInN bandgap and the luminescence energies shows a pronounced stokes shift. XPS measurements reveal a staggered band lineup in Al1-xInxN/GaN heterostructures with x>0.25 is found. These findings indicate an indirect transition from the AlInN conduction to the GaN valence band as origin of the luminescence behavior. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)