Direct epitaxial integration of the ferromagnetic oxide EuO with GaAs

Abstract

Oxides and their heterostructures exhibit a plethora of functional properties with a potential for new device concepts. That makes the basis for oxide electronics which, however, stands aside from the currently dominant semiconductor electronics. To bridge the gap between oxide electronics and mainstream technologies, integration of oxides with the ubiquitous semiconductor platforms is necessary but highly challenging. An issue of a particular current interest is synthesis of magnetic oxide/semicnductor structures for applications in semiconductor spintronics. Here, we solve the long-standing problem of direct epitaxial integration of the paradigmatic ferromagnetic semiconductor EuO with GaAs, a workhorse of the modern electronics. We probe different synthetic routes, ranging from low-temperature tuning of reactant fluxes to high-temperature Eu distillation, explore protection of the GaAs surface by a Eu reconstruction. Weak distillation is established as the optimal synthesis route irrespective of the surface protection. The engineering of a direct contact between EuO and GaAs marks a significant progress over previous works employing buffer layers at the interface. It provides an opportunity for spin injection into GaAs within an all-semiconductor structure. More generally, the study makes a platform for direct epitaxial integration of functional oxides with GaAs.