Decomposition of ammonia on ZrB2(0001)

Zirconium diboride has been recently identified as a promising substrate for the growth of Group-III nitride semiconductors using reactive vapors that include ammonia as the nitrogen source. Adsorption energies and dissociation pathways of NH3 on the (0001) surface of ZrB2 were investigated using density functional theory calculations. Our results indicate that NH3 readily adsorbs onto the ZrB2 surface terminated with Zr and decomposes to atomic N and H with relatively small activation barriers. The resulting atomic species are found to be mobile with the computed diffusion barriers between 0.11 and 0.78 eV.