Nonequilibrium Quantum Electron Transport Properties of Functional Interfaces

碳化硅器件中长期存在的接触问题的起源可以在原子水平上理解和技术上操纵。利用先进的透射电子显微镜，我们定性地将碳化硅欧姆接触的形成归因于外延、相干和原子有序的界面。第一性原理计算预测，该界面可以捕获碳原子层，从而降低肖特基势垒，增强量子电子传输。在a位过量的非化学计量氧化物La_<0中发现了前所未有的绝缘体到金属的转变。5> Sr_<n+ 1-0。5> TinO_<3n+ 1>，发现是由绝缘的SrTiO_3单元电池驱动的。由于电子和声子的复杂相互作用，这种转变伴随着电子定位，并且不寻常，因为大多数电子在导电阶段被限制在形成二维电子气体的原子层内。

The origin of the long-standing contact issue in silicon carbide devices can be understood and technologically manipulated at atomic level. Using advanced transmission electron microscopy, we attributed qualitatively the formation of ohmic contacts to silicon carbide to an epitaxial, coherent, and atomically ordered interface. First principles calculations predict that this interface can trap an atomic layer of carbon and hence enable lowered Schottky barrier and enhanced quantum electron transport.An unprecedented insulator-to-metal transition has been discovered in A-site excess, nonstoichiometric oxides, La_<0. 5> Sr_<n+ 1-0. 5> TinO_<3n+ 1>, which is found to be driven by an insulating SrTiO_3 unit cell. The transition is accompanied by electron localization due to a complex interplay of electrons and phonons, and is unusual as the majority of electrons in the conducting phase are confined to within an atomic layer forming a two-dimensional electron gas.