Niobium nitride (NbN) is widely used in high-frequency superconducting electronics circuits because it has one of the highest superconducting transition temperatures ( T c ∼ 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 films (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 parameter ( k F ℓ ) ∼ 12. Accordingly we observe T c ∼ 17.06 K (point of 50% of normal state resistance), the highest value reported so far for films of thickness 50 nm or less, indicating that HTCVD could be particularly useful for growing high quality NbN thin films.

The deposition of single SiC crystals has been processed inside a sealed enclosure at temperatures above 2300 K and pressures lower than 5 ⋅ 10³ Pa by the modified Lely method. The purpose of this work is to examine the potentialities of different macroscopic models, thermodynamics, heat, and mass transfers on the simulation of the growth of such crystals with a special emphasis on their coupling mechanism. Thermodynamic modeling has been used to determine the most important reactive species involved in equilibrium conditions. Induction heating modeling has allowed the calculation of the actual temperatures inside the reactor which are not well known because of the difficulty associated with their measurements. Finally, mass transport modeling provided the calculated deposition rate. It was found that the calculated growth rates were close to the experimental ones which may indicate a good representation of the actual phenomena involved in the crucible. As a matter of fact each of the proposed models has contributed to a better knowledge of the process.