Abstract
The purposes of this study were to investigate the applicability of competitive growth theory on the texture evolution of VN thin films and the effect of texture on the mechanical properties of VN thin films. Considering the similarity of atomic configuration, the formation of (200) plane of VN (NaCl structure) may follow the (110) template in vanadium metal (BCC structure). In addition to the competitive growth theory, the template effect due to base metal may be an important factor for the texture evolution of the corresponding transition-metal nitrides. For the VN thin films with texture ranging from (200) to random (region I), the preferred orientation gradually changes from (200) to random texture with increasing nitrogen flow rate. VN thin films with (111)-dominant texture can be deposited with increasing nitrogen flow rate and under low energy conditions with low temperature and low substrate bias. The microstructure of VN thin films and mechanical properties were divided into two regions according to texture coefficient. The film microstructure in region I belongs to zone T structure with dense columnar structure and smooth surface, while that in region II has zone I structure with loose columnar structure and rough surface. The film hardness of in region I is about 30 GPa and weakly texture-dependent, while that in region II is quite low and texture dependent ranging from 5.7 to 11.4 GPa. The residual stress of films in region I decreases from -5.66 to -2.66 GPa with increasing (111) texture coefficient, while that in region II is mostly relieved due to loose microstructure, ranging from -0.44 to 0.45 GPa. The electrical resistivity of the understoichiometric samples is higher than that of stoichiometric samples except for the sample with (111)-dominant texture. In addition, loose-packed microstructure also causes higher electrical resistivity.