The evolution of surface morphology and microstructure during growth of single crystal TiN(001) is characterized byin situscanning tunneling microscopy and postdeposition plan-view transmission electron microscopy. The TiN layers are grown on MgO at 650<T<750 °C using reactive magnetron sputter deposition in pureN2.The surface morphology is dominated by growth mounds with an aspect ratio of ≃0.006; both the roughness amplitude and average separation between mounds approximately follow a power law dependence on film thickness,t&agr;,with &agr;=0.25±0.07. Island edges show dendritic geometries characteristic of limited step-edge mobility at the growth temperature. ©1997 American Institute of Physics.