We report the growth of cubic GaN/AlN superlattices by plasma-assisted molecular beam epitaxy on 3C-SiC substrates. The samples consist of 100 nm thick unintentionally doped GaN buffer and 20-40 period superlattices of silicon doped GaN quantum wells embedded in undoped AlN barriers. The thickness of the AlN barriers is varied between 1.5 nm-3.2 nm, while the thickness of the GaN well varies between 1.5 nm-12.5 nm. The growth was controlled by in situ reflection high energy electron diffraction. The structural properties of our samples were studied by high resolution x-ray diffraction. Two superlattice satellite peaks in the x-ray spectra reveal a high structural perfection of the active region. Clear evidence for inter- and intrasubband transitions was observed in photoluminescence, absorbance and photoconductivity spectra measured at room temperature. Model calculations show the possibility to fabricate devices for the near- and far infrared region. (© 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)