We report the growth of cubic GaN/AlN multi quantum well (MQW) structures by plasma-assisted molecular beam epitaxy on 10 μm thick 3C-SiC on top of 300 μm silicon. The samples consist of 115 nm thick GaN buffer and 20 periods of GaN/AlN active regions. The thickness of the AlN barrier is 1.48 nm for all samples, while the thickness of the GaN quantum wells varies between 1.36 nm-2.94 nm. The growth was observed by in-situ reflection high energy electron diffraction (RHEED). The structural properties of our samples were studied by high resolution x-ray diffraction (HRXRD). Several peaks in the HRXRD spectra reveal a high structural perfection of the MQW region. Clear evidence for inter- and intrasubband transitions was observed in photoluminescence (PL) and infrared absorbance spectra measured at temperatures between 2 K and 300 K. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)