  Niobium nitride (NbN) is widely used in high-frequency superconducting
electronics circuits because it has one of the highest superconducting
transition temperatures ($T_c$ $\sim$ 16.5 K) and largest gap among
conventional superconductors. In its thin-film form, the $T_c$ of NbN is very
sensitive to growth conditions and it still remains a challenge to grow NbN
thin film (below 50 nm) with high $T_c$. Here, we report on the superconducting
properties of NbN thin films grown by high-temperature chemical vapor
deposition (HTCVD). Transport measurements reveal significantly lower disorder
than previously reported, characterized by a Ioffe-Regel ($k_F$$\ell$)
parameter of $\sim$ 14. Accordingly we observe $T_c$ $\sim$ 17.06 K (point of
50% of normal state resistance), the highest value reported so far for films of
thickness below 50 nm, indicating that HTCVD could be particularly useful for
growing high quality NbN thin films.
