In order to confirm the superconductivity observed in hexagonal ϵ-NbN reported recently, we have deposited NbN film on (0001) 4H-SiC substrate, with good lattice match, intentionally to grow hexagonal NbN phase. The detailed structural analysis show that the deposited films are (111)-orientated δ-NbN phase with dense rotational (60) twins. Double diffraction effect in selected area electron diffraction and Moir fringes in high resolution transmission electron microscope images confirm the existence of rotational twins in nanometer scale. The growth of highly twined film results from no energy preference for the two rotational twins of (111)-orientated δ-NbN to bond with the Si-faced (0001) 4H-SiC substrate. These highly twined δ-NbN epitaxial films exhibit high normal state resistivity, lower T _C, but good spatial uniformity of superconducting energy gap. No ϵ-NbN phase was observed in this study which is might due to a low growth temperature of thin film.

为了确认最近报道的六方ϵ -NbN的超导性，我们在（0001）4H-SiC衬底上沉积了晶格匹配良好的NbN膜，目的是生长六方NbN相。详细的结构分析表明，沉积的薄膜为（111）取向的δ- NbN相，具有密集的旋转（60）孪晶。高分辨率透射电子显微镜图像中选定区域电子衍射和莫尔条纹的双重衍射效应证实了纳米级旋转孪晶的存在。高孪晶膜的生长是由于没有能量偏爱的，这是因为（111）取向的δ- NbN的两个旋转孪晶与硅面（0001）4H-SiC衬底结合。这些高度缠绕的δ-NbN外延膜具有较高的常态电阻率，较低的T _C值，但具有超导能隙的良好空间均匀性。没有ε在本研究中是威力观察由于薄膜的生长温度低-NbN相。