A novel superlattice structure based on epitaxial nanoscale layers of NbO,. and Nb-doped SrTiO, is fabricated using a laycr-by-layer approach on lattice matched LAO substrates. The absolute Seebeck coefficient and electrical conductivity of the [(NbO_x/(Nb-doped SrTiO3)_b]_(20) super-lattices (SLs) were found to increase with decreasing layer thickness ratio (a/b ratio), reaching, at high temperatures, a power factor that is comparable to epitaxial Nb-doped SrTiO3 (STNO) films (~0.7 W m~(-1) K~(-1))-High temperature studies reveal that the SLs behave as n-type semiconductors and undergo an irreversible change at a varying crossover temperature that depends on the a/b ratio. By use of high resolution X-ray photoelectron spectroscopy and X-ray diffraction, the irreversible changes are identified to be due to a phase transformation from cubic NbO to orthorhombic Nb2O5, which limits the highest temperature of stable operation of the superlattice to 950 K.
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机译：基于NbO的外延纳米级层的新型超晶格结构。在晶格匹配的LAO衬底上，采用Laccr逐层方法制备了Nb掺杂的SrTiO。发现[（NbO_x /（Nb掺杂SrTiO3）_b] _（20）超晶格（SLs）的绝对塞贝克系数和电导率随层厚度比（a / b比）的减小而增加，达到高温，其功率因数可与外延掺Nb的SrTiO3（STNO）薄膜（〜0.7 W m〜（-1）K〜（-1））相比较-高温研究表明SL的行为类似于n型半导体并在取决于a / b比的变化温度下经历不可逆变化通过使用高分辨率X射线光电子能谱和X射线衍射，可以确定不可逆变化是由于立方NbO的相变正交晶态的Nb2O5，将超晶格稳定运行的最高温度限制在950 K.
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