Constructing oxide interfaces and heterostructures by atomic layer-by-layer laser molecular beam epitaxy

Advancements in nanoscale engineering of oxide interfaces and heterostructures have led to discoveries of emergent phenomena and new artificial materials. Combining the strengths of reactive molecular-beam epitaxy and pulsed-laser deposition, we show here, with examples of Sr 1+ x Ti 1- x O 3+δ , Ruddlesden–Popper phase La n +1 Ni n O 3 n +1 ( n = 4), and LaAl 1+ y O 3(1+0.5 y ) /SrTiO 3 interfaces, that atomic layer-by-layer laser molecular-beam epitaxy significantly advances the state of the art in constructing oxide materials with atomic layer precision and control over stoichiometry. With atomic layer-by-layer laser molecular-beam epitaxy we have produced conducting LaAlO 3 /SrTiO 3 interfaces at high oxygen pressures that show no evidence of oxygen vacancies, a capability not accessible by existing techniques. The carrier density of the interfacial two-dimensional electron gas thus obtained agrees quantitatively with the electronic reconstruction mechanism.