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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.