ZrB2 thin films deposited on GaN(0001) by magnetron sputtering from a ZrB2 target

ZrB2 films were deposited on 900°C-preheated or non-preheated GaN(0001) surfaces by direct current magnetron sputtering from a compound target. Analytical transmission electron microscopy and scanning transmission electron microscopy with energy dispersive X-ray spectroscopy and electron energy loss spectroscopy revealed a 0001 fiber textured ZrB2 film growth following the formation of a ~2nm thick amorphous BN layer onto the GaN(0001) at a substrate temperature of 900°C. The amorphous BN layer remains when the substrate temperature is lowered to 500°C or when the preheating step is removed from the process and results in the growth of polycrystalline ZrB2 films. The ZrB2 growth phenomena on GaN(0001) is compared to on 4H-SiC(0001), Si(111), and Al2O3(0001) substrates, which yield epitaxial film growth. The decomposition of the GaN surface during vacuum processing during BN interfacial layer formation is found to impede epitaxial growth of ZrB2.