The DEVICE software includes an electrical and a thermal solver. The material database therefore contains electrical and thermal properties of materials and is very different from the material database used in the optical solvers (FDTD or MODE Solutions). Therefore, material models are not transferable between DEVICE and FDTD Solutions/MODE Solutions.
If you would like to use nitride material models in FDTD, you can easily create a new material in FDTD (or MODE) Solutions. Please check this post to see how you can do that: