NbN和MoN薄膜的溶液法制备、生长机理及性能调控研究

Due to the combined properties of high hardness and high superconducting transition temperature in NbN and MoN thin films, these two materials are considered as hard superconductors. Currently, the NbN and MoN thin films are usually prepared using vacuum-based methods. Additionally, the thin films are needed to be treated under high pressure to obtain high superconducting transition temperature, and the physical mechanisms are not yet clear currently. Based our previous results about metal-nitride superconducting thin films, in this proposal we will prepare NbN and MoN thin films with high superconducting transition temperature by chemical solution deposition under ambient pressure. The growth mechanisms as well as the microstructures and physical properties will be investigated. The main factors in controlling of the superconducting transition temperature will be studied and the correlation between processing, N content, carrier concentration, normal resistivity and superconducting transition temperature will be established. Through processing parameters, the upper critical field will be improved and the vortex phase diagram will be constructed. The results will provide guidance to optimize the properties of NbN and MoN thin films.

NbN和MoN薄膜由于其较高的超导转变温度及高硬度，被认为是一类特殊的硬质超导体。目前这两类薄膜的制备基本采用真空法进行，且为了获得高的超导转变温度需进行高压处理、物理性能的调控机理尚不清楚。本项目在我们已有金属氮化物超导薄膜的研究基础上，采用适合大尺寸薄膜生长的溶液法制备NbN和MoN薄膜，在常压烧结条件下获得高超导转变温度的薄膜。探索NbN和MoN薄膜的生长机制并构建薄膜生长相图、通过工艺参数对薄膜的微结构和晶界特性及超导性能进行调控。揭示影响NbN和MoN薄膜超导转变温度的主要影响因素，建立微结构-N含量-载流子浓度-正常态电阻率-超导转变温度之间的关联；通过微结构优化显著提高NbN和MoN薄膜的上临界场，弄清楚薄膜微应力及晶界特性对上临界场的调控影响因素并绘制磁通相图。为具有高超导转变温度NbN和MoN薄膜的生长、微结构及超导性能调控提供实验和理论依据。

NbN和MoN薄膜由于其较高的超导转变温度及高硬度，被认为是一类特殊的硬质超导体,这两类薄膜的制备基本采用真空法进行，而且为了获得高的超导转变温度需进行高压合成制备。本项目采用适合大尺寸薄膜生长的溶液法开展了常压下NbN和MoN薄膜制备及性能方面的研究。获得了如下的结果：1）化学溶液法在常压下可获得具有高超导临界温度的NbN和MoN薄膜；2）通过烧结过程的温度控制，可有效调制薄膜的N含量，进而影响薄膜的超导转变温度；3）通过膜厚控制，可有效调节薄膜的微应力，随着膜厚增加薄膜的晶化质量提高，超导转变温度提高；4）通过前驱胶体调制，可制备出外延NbN和MoN薄膜。这些结果为具有高超导转变温度的NbN和MoN薄膜的生长、微结构及超导性能调控提供实验和理论依据。