[en] In the present study, GaN/AlN double heterostructure (DH) has been grown by plasma assisted molecular beam epitaxy. The crystalline quality and interface properties of the grown heterostructure were analyzed by various characterization tools. The studies reveal that highly single crystalline GaN and AlN films have been grown epitaxially on sapphire substrate with X-ray rocking curve full width half maximum value of 4.8 arcmin and 8.4 arcmin respectively. A sharp interface between GaN and AlN layers in the grown hetero-structure has been observed with minimum diffusion of Gallium metal in the AlN film. Such good crystalline quality film and sharp interfaces are necessary for successful implementation of high efficiency devices. (author)