Impact of surface morphologies of substrates on the epitaxial growth of magnetron-sputtered (ZnO) _x(InN)_1-xfilms

The effects of substrates on the growth of sputter-deposited (ZnO) x (InN)1-x (called "ZION"hereinafter) films have been investigated. We defined the figure of merit (FOM) of ZION films as the reciprocal of the product of full width at half maximum of X-ray rocking curves and root mean square (RMS) roughness. No clear correlation between the FOM and the RMS roughness of the substrates is observed; however, interestingly, a strong correlation between the FOM and the "skewness"of the surface height distribution of the substrates is observed. A possible reason for this is that the existence of a small portion of spikes on the surface, which appear as tiny tails in the distribution but are not reflected in the RMS roughness, limits the migration of adatoms and/or leads to secondary nucleation, degrading the quality of the subsequently grown ZION films. In addition, an atomically flat single-crystalline ZION film is grown on a ZnO template with a small skewness of 0.04.